Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: shooter on September 24, 2019, 10:17:26 pm
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followed Sluckeys link for dark on 1482, found Platefires take, it's getting colder so...
still sketchin, my OT is 1250:8 so I gotta do some creative figurin for PA tubes n speakers.
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followed Sluckeys link for dark on 1482, found Platefires take, it's getting colder so...
still sketchin, my OT is 1250:8 so I gotta do some creative figurin for PA tubes n speakers.
what's wattage spec on that OT? 1/2 primary Imax? the latter is usually a longshot spec. (rarely given).
--pete
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> my OT is 1250:8
Seems unlikely.
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Seems unlikely.
It was late :laugh:
It's Edcor (no number yet), 1250:4 at 250mA 25W.
I used it in a QSE el84 audio, bought 2, one left, n......
leaning to EL34's again, but I don't have any.
6V6 I have, got 2 16ohm speakers n 1 8ohm but it's a couple hours before my brain wants to get serious :icon_biggrin:
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6CW5 - 200V B+ in AB1 with a 8 ohm secondary load.
http://www.nj7p.org/Tubes/PDFs/Frank/093-GE/6CW5.pdf (http://www.nj7p.org/Tubes/PDFs/Frank/093-GE/6CW5.pdf)
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where is this link? followed Sluckeys link for dark on 1482
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http://el34world.com/Forum/index.php?topic=25020.0
Pg1 rely 33
also, this IS an experiment, the OT IS for SE, with a 40% tap for screens, but as an experiment was gonna try and use it PP and balance the PI's 68k's for ~~symmetrical a/b.
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2shots of espresso and a coffee later;
looks like 6V6 will get close into a 32ohm(2X12 16ohm ea) load based on a quicky look at datasheet
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NOT P-P but just a suggestion. seems like it would work - it has a god reference. :p
--pete
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:laugh:
60W pdiss!!! :think1:
I do have a PSE 6V6 sketched, if I got the datasheet correct should want ~~ 2500ohms plate. (2X12 wired as 8ohm)
the main reason for PP (not a big fan:), I can add Steve's tremolator, which keeps it 1482esq :w2:
not sure where I'd be able to use it to wiggle pre-amp/driver tubes if I went PSE
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Gonna stick with the PP, added Sluckeys tremolator circuit, probably use the extra 1/2 tube to convert TS recovery stage to DCCF.
I borrowed with impunity Platefires NFB circuit. He has it at 8ohm tap, i'll be using the 4ohm, will my divide by 2 math work as starting points for the R's in the NFB circuit?
thanks
dave
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I'm not getting how this amp is 1482-ish
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cuz that's where inspiration hit me :icon_biggrin:
once that thing happens, as an artist I've learned to go with it
so, following "why so distorted", link to Platefire, lightbulb, ........... :dontknow: :w2: :BangHead: :laugh:
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Gonna stick with the PP, added Sluckeys tremolator circuit, probably use the extra 1/2 tube to convert TS recovery stage to DCCF.
I borrowed with impunity Platefires NFB circuit. He has it at 8ohm tap, i'll be using the 4ohm, will my divide by 2 math work as starting points for the R's in the NFB circuit?
thanks
dave
sqrt2 * Rfb @ 4ohm = Rfb for 8ohm. to go the other way, take the inverse - 1/sqrt2 * Rfb @ 8ohm = Rfb @ 4ohm
--pete
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Thanks Pete, now to find the sqr root key :laugh:
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Squared the roots, tweaked the schematic.
any flashing red lights I missed? Or like me, dim bulbs? :icon_biggrin:
(PS rail R's are just placeholders till tweaking time)
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tweaked the schematic.
Don't forget to label V1,2,3 so none of these crazy kids try to use all 12AU7s
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any flashing red lights I missed?
Hopefully there will be one inside that optocoupler. I'm really interested to know if that will wiggle the 6V6s in a strong good way. Keep us posted.
BTW, when did you get back into push/pull?
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Don't forget to label V1,2,3
they are labeled V1A, V1B.....tube type optional :icon_biggrin:
N ya, 1 or 2, maybe 3 will be AU7, what of it :m20
when did you get back into push/pull?
I haven't really, I'm just faking it :laugh:
trying to use up the weight laying around the house, It has been ~~ 4yrs since the last time so guess I wanta see if I still can :icon_biggrin:
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> any flashing red lights I missed?
There's no NFB until you ground the other side of the secondary.
Using a 1.25k OT as a 8k OT is liable to shave two octaves of bass. (However it is a hi-fi OT so it may end up OK for gitar.... downside is it is about 4X the weight you really needed.)
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Thanks Pete, now to find the sqr root key :laugh:
Xy is your sqrt key. sqrt is 2.5
--pete
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.
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.
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back on topic...
buy some EL34. :icon_biggrin:
EL34s with 32Ω secondary load is near to perfect fit for wonky OT.
see mullard EL34 datasheet.
--pete
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.
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:laugh:
HA, I used the Y fishhook X one,
The NO NFB I think Platefire designed like that hence the funky Center off switching.
N buying is out for now, I spent my Christmas money on SS heavy metal etal :icon_biggrin:
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I found Platefires P2P layouts, NICE work! If anyone has done a board version for reference :dontknow:
downside is it is about 4X the weight you really needed.
Cost about that much more also :icon_biggrin:
I am willing to entertain a swap with someone all SE geeky :laugh: (pm me)
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.
Well, yes, mine defaults to Sci mode; but I figured it probably comes up in BASIC mode for most people.
I have a slipstick and a TI-30, so I don't use WinCalc often. Is there a way to lose that wide useless side-bar?
BTW, calculators with Square Root have been under $2 for like 20 years now. I have seen 50 cents. Dollar stores often have a SqRt calc cheap. My grocery store has a $2 SqRt calc but they want $4 for it. If you want a "real" calculator, WalMart sells the TI-30(Xa) for about $9. Try to get it to turn-on and do something to show the decimal point-- for several years they used dots too small for anybody who was booted out of school a long time ago.
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Is there a way to lose that wide useless side-bar?
Not that I've found. when I was trying to teach myself Python I tried to CALL the calculator sub, hung the system. moved on to the call for a usb port, really trashed the system, gave up on learning C :BangHead:
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I stole this question from this link
http://el34world.com/Forum/index.php?topic=25086.50;topicseen
Hey I have a layout question
?
stole a couple pics from current threads
the real question, does anyone know, have any "best practices" for spaghetti builds?
the 1482 layout is spaghetti type example
I get the P2P clean, well thought.......
but I've looked at these type "examples" and cannot find ANY "discernible patterns"
thanks
dave
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Did some chip throwing on the table saw, I like sawdust better!
for now, terminal strips, in some logical arrangement on the underside of top. bottom will slide in "tracks" on the main chassis (previous casting:), sides caped with wood, copper lined :icon_biggrin:
toying with Dougs BJ tube board suspended below so ~ 1/3 of the 12??7s are visible :dontknow: NOT built for gigging :laugh:
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re-worked layout, edited a perfectly good layout for my use Thx :laugh:
no BJ board, lots of metal work :think1:
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Don't you wish you had Visio?
There are several real P2P amps on my website, some simple, fairly clean, also some boogers. Don't let the Maggie M10-A scare you!
BOO! :l2:
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Don't let the Maggie M10-A scare you!
HA;
I rode the 7Sea's, climbed vertical rock for fun, taught other ppls teens! not much left to scare me :icon_biggrin:
I will take a look, thx
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:w2:
ok, I was wrong, the orange fuzzy stuff from Chester's Chevy van was kinda creepy :icon_biggrin:
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got 2 free "blanks" from my office supply Ladies, they like me :icon_biggrin:
1st doodle, lookin like spaghetti :think1:
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from here;
http://el34world.com/Forum/index.php?topic=25086.0
I grabbed the trem.tst, then got confused :laugh:
It's a semantics confusion, Isn't the original INT closer to "bias very" and the circled INT "signal very"?
thx
dave
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I have no clue what you just said. :dontknow:
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from what I've learnt/learning there are 2 basic tremolo "insertions" one type "bias vary" usually at the grid of fixed bias tubes with 2 mixing R's
the other "type" insert at cathode of a pre-amp
I'm trying to get the "proper terms" in my head or on paper.
I have 1 type "mixing/blending" with signal
the other type altering the tubes bias causing the signal to "alter" at trem rate NOT mix.
your schematic "seems" to be both types, just trying to note which is called which.
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I'm a little more clear headed this morning. :icon_biggrin: Now I understand. But, in my mind both are bias vary circuits. One circuit varies the bias voltage on the cathode of a small signal triode. Not much trem signal amplitude needed. The other varies the grid bias voltage on the power tube. It's true that the grid voltage is normally zero, but that's only half the info. The bias on the output tube is the difference in voltage on the grid and cathode, and that may be 15 or 20 volts. Now put a slow moving 20Vpp sine wave on the grid and the grid voltage slowly swings + 20V, centered around zero. Seems like bias vary trem to me.
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I'm a little more clear headed this morning. :icon_biggrin:
mee2 :laugh: although that means back in the crawl space n tin-knockin :BangHead:
your explanation is "where I'm at" sept wiggling the grid of a self biased PA tube, that one's still full of squirrels n bats.
Rk typically sets bias, G1 AC signal "just" gives the tube something to amplify (input sig +/- trem signal) not alter "bias" :dontknow:
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G1 AC signal "just" gives the tube something to amplify (input sig +/- trem signal) not alter "bias"
The AC signal on any amplifier grid absolutely does vary the tube bias. That's how amplifiers work. Small ac voltage on the grid varies the bias and causes current through the tube (and plate resistor) to vary. This varying current through the plate resistor causes a larger varying voltage to be dropped across the resistor. Abracadabra. You have gain.
Let's do it differently... No signal, just a linear pot on the grid of a cathode biased tube. (Just for shits and grins let's call the pot INT.) We have a +12v on the top side of the pot and we have a -12V on the bottom of the pot. With the pot set to the middle we send zero volts to the grid. Let's call this the quiesent state. Zero volts causes some current to flow through the tube. A certain voltage will be dropped across the cathode resistor and a voltage will be dropped across the plate resistor. Everything just sits like that in a quiescent state. Now crank the pot all the way down to -12V. This will cause the tube to conduct much less, the cathode voltage will decrease and the plate voltage will increase. Notice that the plate voltage did just the opposite of the grid voltage. It's inverted. Now crank the pot all the way up to +12V. The tube conducts heavily. Cathode voltage goes up. Plate voltage goes down. Inverted again.
If you're still awake, try this... Crank that pot back and forth about 5 times per second. What do you think happens? Are you varying the bias? Could you call this bias vary tremolo? :icon_biggrin:
It makes no difference if you vary the voltage on the cathode or the grid. The results are the same because bias is defined as voltage difference ***BETWEEN*** grid and cathode.
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If you're still awake
:icon_biggrin:
ok, the bats n squirrels have been replaced by happy birds singing! :laugh:
so now back to my original thought that got me all sideways :think1:
IF I use a BIG wabble on G1 experimenting should I keep an eye on tube current since SE bias is typically "set" for 90 -100 % dissipation or is the low duty cycle "low enough" not to push dissipation to worrisome places :dontknow:
LUNCH BREAK :icon_biggrin:
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IF I use a BIG wabble on G1 experimenting should I keep an eye on tube current since SE bias is typically "set" for 90 -100 % dissipation or is the low duty cycle "low enough" not to push dissipation to worrisome places
Nope. Just build as if there were no tremolo. Ground the grid resistors or just set the INT to zero. BTW, the wiper of the INT pot is a great place to put the footswitch. Set the bias as you normally would. Then lift the junction of the grid resistors from ground and connect to the wiper of the INT pot. If it turns out you have too much intensity your ears will tell you. If so, just put a resistor in series with the top side of the INT pot. Experiment with resistor value until you have a suitable intensity without "whoop whoop" or thumping/pumping in the speaker. And if you really want to prevent the grids from going positive, just put a diode across the INT pot so it clips the positive half cycle of the tremolo signal.
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just put a diode
I like it!
I'm gonna use pull on INT pot for trem on/off and pull on speed pot for swamp on/off
BUT I need long thread mounting, that's a hunt for another day :laugh:
thanks for the clarity, I'll try not to ask any goofy questions for 2 days :icon_biggrin:
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updated doodle
change notes next :think1:
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found ~ 6 errors :think1:
wired 3 more circuits, came up with a question;
the trem circuit needs 5 "fly" wires, any downside to using cat5?
If I fly the hypotenuse ~ 6", if I skirt the sides ~ 15"
if cat5 is out any downside bundling and taking the long way ?
thanks
dave
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I'm sure silvertone would have specified CAT5 if it had been around in the '60s. :l2:
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:l2:
I was 'ol ppl shoppin today at lake M. looked EVERYWHERE for a press-board, press-cardboard box for the chassis :icon_biggrin:
that said, I want a 5E3 killer :icon_biggrin:
1st pass will probably fall short with the OT, but I'm an optimist :laugh:
none of the trem wires seem to carry sensitive stuff and I still got 100's of ft left. :dontknow:
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On paper I’m soldering 68K at pin 2, jumper 2 to pin 7
Has anyone found the single R problematic compared to 2 R’s?
Thanks
Dave
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I new better but...
2 broke bits n some ugly later :laugh:
it'll get some cleanup n a paint job later, no one will know :icon_biggrin:
time to hunt up the web for slider pots n switches, that'll be fun cutting in :think1:
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Tube sorting n winter packing
1 6V6 :BangHead:
Lots of 6K6 (I think, it’s a lower watt 6V6-like)
Lots of 6BQ6 :icon_biggrin:
Found this thread – GREAT analysis!
http://el34world.com/Forum/index.php?topic=11766.msg109161#msg109161
what I’ve gleaned I want ~120vdc @ ~ 50mA for 2 tubes?
Is it possible to get close with a 1:1 isolation transformer for wall power?
I know, go fish
also unburied a 5K : 8 (still SE 40%ul @25W, still edcor:)
Thanks
dave
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Back to the mini-ice-age so back to this build
Using 6K6 tubes for prototyping since I have 10 n 0 6V6s.
(I will probably buy a "proper" PP OT, but stil gotta get to 12k making sense)
Getting hung on plate to plate effective load, data sheet shows 12K
When I take 285vdc / 60mA it suggests 4750 Ω
So I’m missing something I forgot ! :w2:
The other hang-up is the graph. My OT is way off (SE UL, discussed previously) but with speaker impedance manipulation, I can get to 7k Ω, or 14k Ω
Plotting a line on the graph at 7k looks to be a good option, better than 4750 (math) and 12k data-sheet :dontknow:
Thanks
dave
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sorry - what i had posted was not relevant to the Q. not relevant to your question.
PRR gave us a lecture on+ P-P in class A1 some years back - basically SE calculation x 2.
salt & pepper to taste. around these parts we like chili's and jalapenos.
--pete
EDIT: content.
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ok, so translating So. Texas to farm Michigan, the OT impedance is arbitrary within reason? :dontknow:
all my builds so far are based on data sheet n ballparking based on plate volts n current which are close-ish. The data sheet n math are pretty far apart here :dontknow:
thanks
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> plate to plate effective load, data sheet shows 12K
When I take 285vdc / 60mA it suggests 4750 Ω
Looks like SE math on a P-P amplifier.
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:laugh:
I'm Myopic that way
so I'd double that math in PP? or find something new :dontknow:
still kinda hung on the graph, I added green lines, the left vertical ~ matches the math, the 12k appears to show power out n distortion ~ the same :dontknow:
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http://www.valvewizard.co.uk/pp.html (http://www.valvewizard.co.uk/pp.html)
http://www.valvewizard.co.uk/se.html (http://www.valvewizard.co.uk/se.html)
Franco
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Thanks K, was heading there next, you just pushed me :laugh:
did steal this math for cheating;
P = 2 * (HT-50)^2 / Rload. just got to get Rload on the other side of ='s :laugh:
one thing, the data sheet above is for PP class A1 (unless that's a typo), I was assuming it would operation closer to 2SE than AB1. Now I gotta go refresh my brain on amp class operation :think1:
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> still kinda hung on the graph
That is for Single Ended.
A simple translation to push-pull would Double the impedance.
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That is for Single Ended
thank you !!
shoulda seen that with the left side reading 3.5W :think1: :cussing:
now I can sleep well!!
one more annoying question,
the green lines do "appear" to yield the same results at ~ 5k and 12K.
my guess the tube works less hard for the same output (power) because the impedance is closer to ideal at 12k :dontknow:
appreciate the time, thanks
dave
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When n bit the 30-30 and ordered this OT
XPP15-10K, good price, shipping was NOT :cussing:
figure 10k is close enough to 12k n I get the UL taps I want. The dimensions look like it might fit below decks so the wires will be out of the way to unsuspecting fingers :icon_biggrin:
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I'm pretty confident in my ability NOT to do a flaw free 'old style P2P build so I basturdized one of Sluckeys master pieces :icon_biggrin:
still an in-progress paint edit :think1:
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10k gonna work fine. it's not Hi-fi. :dontknow: or is it?
--pete
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it's not Hi-fi. :dontknow: or is it?
the amp, no. the OT :dontknow:. It is UL, over rated for the build n Edcor made so it could swing either way shy of cork-sniffer Hi-Fi. Plan on mating it with my Altec VoT 15"
In my cobwebs I "hear" clean chimey til ~ 6. from there to 10 progressively crankier :icon_biggrin:
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decided to move to crayons :icon_biggrin:
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When you gonna come over to the dark side and quit painting on those purty Visio drawings? Visio will unleash a whole new artist in you. Easy peasy for you.
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decided to move to crayons :icon_biggrin:
https://www.libreoffice.org/discover/draw/ (https://www.libreoffice.org/discover/draw/)
dude! it's free! :icon_biggrin:
--pete
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:laugh:
I have a fully loaded Correl draw on a Win '95, but it ain't been booted in 12yrs :icon_biggrin:
I can even do a pretty good layout with .sch(.pcb) but there is something therapeutic about putting DOWN the mouse and picking up drafting templates n pencils :m17
thanks for trying though :occasion14:
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i use CAD to design stuff i'll probably never build. just the opposite, but that's my therapy.
the PCB is for a AB763 preamp minus the tremelo + plexi preamp: switching and LTPI are on another PCB and board uses eyelets for external connections.
--pete
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just the opposite
I did a complete set of drawings for my house, 11 pages, with Correl draw. when I submitted them for my building permits the guy ask what Architect firm I used :icon_biggrin:
At heart though, I will always be Analog by default :laugh:
I'm working with the township to help draft an Ordinance to restrict BIG energy from putting 300' towers with propellers in our back yards. I asked where they had the research data, the reply FB, I laughed since FB won't let me look because I won't join their gang
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PRR gave us a lecture on+ P-P in class A1 some years back - basically SE calculation x 2.
sorry missed THAT reply!
I'm finalizing the BOM, the datasheet says 400ohms Rk. I have 2, but I've seen enough original schematics that typically use 1 Rk.
Can I assume the datasheet means 2 400's :dontknow:
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PRR gave us a lecture on+ P-P in class A1 some years back - basically SE calculation x 2.
sorry missed THAT reply!
I'm finalizing the BOM, the datasheet says 400ohms Rk. I have 2, but I've seen enough original schematics that typically use 1 Rk.
Can I assume the datasheet means 2 400's :dontknow:
respectfully, but query is ambiguous - a specific datasheet/case would be helpful. 400Ω for one tube or two? is datasheet SE class A or P-P class A
--pete
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sorry, the one I posted earlier above.
it's PP A1
I looked at a couple datasheets then amps with 1Rk, making a crayon note to self datasheets are 1Rk per tube, which is logical.
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if it states "values for two tubes" then the cathode resistor value given is for both tubes. if you want to split cathode resistor, one for each 6k6, then you'd need 800ohm for each 6k6.
--pete
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"values for two tubes"
Yup verbatim! and that's why I posed the ?
but then I re-read data sheet n since plate vdc is 285, I was pretty sure that didn't mean 570 each.
62years and I still struggle with my native language :icon_biggrin:
thanks Pete. I'll make sure I have some double values on hand :laugh:
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got the rubber meeting the road :icon_biggrin:
and my 1st :cussing: up :think1:
the last drop R should be 10K, now 2.2k, gonna leave for now til I load it up n see where plate volts land.
can't cut up chassis, missing my OT, and it TOO cold to play with contact cement
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spent the day wandering the inland sea, watching the well-to-do watch their homes move closer to the edge :icon_biggrin:
the boards wired 80% (not shown:), drillin wire holes tonight
dug up an old head box I built for my revibe spaghetti mess, to cold to paint though
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I re-did the red dots to remove PA cathode parts
missed a couple :laugh: :think1:
I didn't want to do over so...It fits :icon_biggrin:
should be 2 weeks then Edocr will wind n ship my coil in about an hour... and 6 weeks :laugh:
it's warming up so I can wait outside :m17
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My friends in New Mexico got bored, OT in the mail!
Me of low knob count has used more than my last 3 builds :think1:
the layout I have for the 1471 has kitty-wampiss knobs, so i'll bite :icon_biggrin:
(random parts are stand ins :)
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the Gov'mnt worker brought my OT!
it's even 48 degrees without SUN!
since I left 3 miles of un-needed board, jugglin pieces is interesting :think1:
gonna watch this layout for now, maybe when the crayons come out it'll change :icon_biggrin:
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busy with life, took time to throw chips, and tweak to artistic :icon_biggrin:
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carbonized 30 cubic FT of shipping boxes eating at my floor!
that opened up enough to find tools, which lead to fitting the big n heavy parts
assembles real easy, dis-assembly requires either LOTS of Sailor speak or Zen patience :think1: hunting for the dremel next to cut the board since it cannot be removed without removing the OT :BangHead:
Neither can be removed once I wiggle the bridge in :cussing:
I berated mechanical engineers my whole professional life, this is karma coming around :laugh:
still not 100% committed to tube position, but real close
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real life ate up most of the day
managed to get the square holes made n fitted, Lowes was a ghost store :icon_biggrin:
the EIA came too close to the OT so I have a couple spare holes :think1:
not worth a pic :laugh:
[/EDITi]:
kinds hung, I missed the pot, now I gotta clean up. designed a dpdt, ordered a spst :think1:
here's my cheat, never build NFB so any electronic "issues", even blaring design faults :dontknow:
was gonna play with hard-wiring the cap during tweaking phase
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Just discovered this! Glad I'm not the only one the projects span a two years :l2: Well I'm looking forward to see what you get.
The reason for my center-0ff switches was allow myself to switch back to original no-NFB. Same reason with cathode bypass caps on the instrument channel.
Platefire
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I borrowed heavily from your version :laugh:
and time in my new life is an abstract concept :icon_biggrin:
I like having the center off, since I've never used NFB I can just leave it OFF if I don't like it, instead of unsoldering
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I use my 1482 every week in Worship Services hooked in parallel to my DiY Champ. I am actually using NFB setting on it right now along with the channel with the Princeton(5F2) tone stack. For some reason I never like the effect of the different cathode bypass caps? seems like they add too much compression. I like compression but use a pedal, so I can adjust it.
LONG LIVE THE 1482 AND THE CONTINUED IMPROVEMENTS
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couldn't get the leaves to carbonize so I bored the tube holes.
2 round n a rectangle hole left. Then it's be-burr, de-grease. Probably just have fun and try n channel some Jackson P. for the paint scheme :icon_biggrin:
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Nice! Just wondering: is your light in your switches clear? I bought a bunch of blue and green switches a while back thinking they'd illuminate blue or green. They put orange bulbs in them so they are orange when they illuminate. Anyways.... looking good!
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AFAIK, NE-2 only comes in orange.
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Oh. I was just wondering. Kinda defeats the purpose of making them blue or green. They definitely don't look blue or green when they're on....at least the ones I have don't.
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All of my rocker switches are either red or orange. They keep true to color, but I'd expect blue and green to be off color a bit.
I have a green lamp on my Leslie footswitch. It uses that same orange NE-2 neon bulb. It looks green to me. It's shining in this pic...
(http://sluckeyamps.com/leslie/leslie_02.jpg)
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Yeah that does keep it's color. I used a blue one for power and green for standby. They both look like identical orange switches when powered up. It's not a big issue for me but it would be cool if they looked blue and green when lit up.
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it would be cool if they looked blue
It looks as blue as Sluckey's looks green if that helps. I use 'em cause it's all in one.
the aesthetics is good, they came in all the colors you mentioned , amber, red, green, n blue.
think I settled on Pollocks, Black period, looking at the Dewalt, dark orange on black keeps humming in my head :icon_biggrin:
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AFAIK, NE-2 only comes in orange.
Yes; but there WERE some "NE-2**" variants. I had some with green phosphor (dunno what the gas color was). https://en.wikipedia.org/wiki/Neon_lamp#Color
If you must have non-orange, LEDs come in all colors, but need a very different power supply (not simply right across the line), and may be hard to retrofit in vintage switches (new switches can be had with LEDs).
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crappy day out, so crayon time came early :icon_biggrin:
working title "FluPoo" :laugh:
2 weeks n it might be dry :think1:
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Crazy! You gonna try to match some tolex to it?
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:l2:
I ONLY build chassis'
I do have a box (posted earlier), but it's rainy n cold so the barn is in isolation :icon_biggrin:
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Mind if I ask where you guys get your switches? Here's a couple on and off pictures.... neither blue nor green.
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That's crazy!
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That all looks really good Shooter. I even like that Jackson P.
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yo mon! i dig on de zydeco chassis. NoLA is calling to you.
--pete
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here's the link to the switches;
https://www.parts-express.com/parts-express-spst-large-rocker-switch-w-blue-illumination-125vac--060-704
and they don't light like yours :laugh:
Pete, I am a closet zydeco listener :icon_biggrin:
got carried away and mixed Pollack's dark period with his splatter years :w2:
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crappy day, tired of watching paint dry, bored watching for tanks, decided to solder some :laugh:
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nuther coldwetgrayday
so I clear-coated a couple layers n busted out the install tools :laugh:
here's the eye candy side :icon_biggrin:
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That's awesome! Cool way to combine visual art and aural art!
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aural art
:laugh:
Long way to go in that genre' :icon_biggrin:
Odd note though, as I was drifting to black last night I "heard" the amp
"Memphis style" bluesy funk :occasion14:
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the SUN showed up, without heat but hey;
starting the Yang side :icon_biggrin:
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messed up my BOM and my spares are low, parts on order :BangHead:
I can't recall if there's a "downside" flipping the secondary wires if she's a screamer :dontknow:
since it's UL, I'd much rather swap 2 than 4
thanks
dave
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I can't recall if there's a "downside" flipping the secondary wires if she's a screamer :dontknow:
since it's UL, I'd much rather swap 2 than 4
Swapping secondaries is fine if there is only one impedance tap to deal with. Multiple taps is a no no. Much easier to just swap the grid wires.
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Multiple taps is a no no.
thanks, I had the fuzzy thought there was a downside, I only got 1 tap though! :angel
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gray cold only broke even on scratch offs, so I added a few yellow marks on the layout and parts inside, waiting to replace the 2banger tone with a singlewide :icon_biggrin:
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just a note for those gleaning insight;
I've caught n fixed 4 problems and the power switch still ain't installed!
I "find" the problems by doing a "mental install" 1st, that caught a mis-draw on V2.
once I do a bunch of soldering, I walk away n play, then come back and "re-do" the same work with my eyes, That found a missed solder point, 2 R's wrong values :BangHead:
remember the turtle always wins :icon_biggrin:
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3+ inches of new snow! after some tracking managed to get the power switch installed n tested, red wires 265vac, brown 6.44vac and zero smoke :icon_biggrin:
think it's time to refresh my reading on "the folly of man", maybe play some Nero fiddling tunes while I wait for the bridge to come :icon_biggrin:
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cold gray no snow but more state boys than I've seen in 2 weeks!
bridge is in the mail!
nothing left to add until I can shoe-horn the bridge in. then.... :laugh:
I have a major design flaw that just might be a "happy mistake" or epic fail.
My pre ends into a DCCF, which feeds a Cathodyne PI, so 2 "buffer" stages :think1:
don't recall ever seeing that. shouldn't be a problem just converting the DCCF to a DCPI and V3A becomes a floater, gain, light flasher, something, or not :w2:
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played outside, got a bridge in the mail, went inside :icon_biggrin:
the command n control side is about done, the working class side next :laugh:
found the neutral wire jumped when I got it hot, re-doing :think1:
still gotta solve the roach but it's music with crayons now
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working class side wired 99%. missed a couple wires during layout so flying :think1:
still sorting the roach, doug says "bulb" in description, is that right, or LED?
probably cut it open IF I can find it, got it isolated to a room :BangHead:
to have "proper phase" do I want the PI in to match the speaker +?
thanks
dave
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still sorting the roach, doug says "bulb" in description, is that right, or LED?
It's a NE-2 neon glass bulb. It's the copper colored leads on the right side in his pic. The bulb is approx 3/16" dia x 1/2" long. Very obvious in Hoffman's pic. The bulb will have infinity resistance. The photo cell (LDR) will have very high resistance. May be able to measure it with your 87V. I've never tried.
In the old days I have used a razor blade to cut a tiny hole directly over the bulb to see if it was flashing. Paint the hole with a drop of fingernail polish when done.
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Thanks Steve
I'm down to a corner :think1:
might have it soldered tonight!
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LOTS to check but;
quiet as any amp I've built, maybe quietest!!!
1st pass;
Vp = 331
Vk = 20.5
Diss = 14.6W/tube oops
moved B+ to second tap
Vp = 217
Vk = 12
Diss = 5.4W /tube safe.
Nice tones, clean with small edge at the 10's. Trem doesn't seem to be there, find out with scope later.
NFB not hooked up so i'll clip it and see about screams.
todo:
run a signal through, gain/volume pretty low, might need to bump V1 to AX
address trem n NFB
overall;
:m17 :m8
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Which trem circuit are you using? Schematic please. Don't need a scope to check the trem. Your 87V works just fine.
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I just checked the schematics you posted in the first few posts. That Fender roach ain't never gonna work in the schematics I saw!
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That Fender roach ain't never gonna work
:laugh: used the 87, nice constant vdc
nope. I have LEDS and photocells and heat sink, does that get me close?
done for tonight
got good clean from in to out, good start
something wonky in PA, IF my #'s are correct, I have ~~ unity gain from PA tubes :think1:
one tube doesn't like me getting close, the AC on the PS taps starts bouncing. got 5 more tubes, + a new 6V6, might just buy the next one, for tweaking using the 6K6's
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Set the trem aside. Fix the amp. Come back to trem.
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Set the trem aside
:laugh:
I read that in ANOTHER thread :icon_biggrin:
already jumped it out, not ready for the on switch yet, coFFEE! :icon_biggrin:
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trem gone, jumped Grid leak 330k's to ground instead of INT pot. (only change from initial checks)
Here's initial current schematic with vdc and Vacrms.
noted changes from last night, gain went up starting at V2a into grid PA, speaker out is same :w2:
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Looks like the amp is working. Is it? Why are you using 12AU7s in places where everyone else uses 12AX7s?
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That Fender roach ain't never gonna work
:laugh: used the 87, nice constant vdc
something wonky in PA, IF my #'s are correct, I have ~~ unity gain from PA tubes :think1:
not possible in grounded cathode fixed bias P-P or cathode bias P-P stages - IOW: you'd need 400V g1 drive with 400V+ B+ to make full power. your math is way off.
--pete
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Why are you using 12AU7s
The AU seems to be better at keeping "too much gain" at bay, the signal comes up better than noise, so less hiss n other related "hi gain" issues.
as long as I can get a drive signal bigger than "bias" to the PA, I'm good.
It sounds like a 5F1 champ as far as loud goes, nice tone, good lows to highs, just not a 10W PP sound like I'd expect from a Gibson skylark kinda amp.
cathode bias P-P stages
you'd need 400V g1 drive with 400V+ B+
lost now;
the datasheet suggests ~ 300 plate, AF peak G-G ~50v (I'm pretty low there), dissipation design center ~ 8+W I'm at 8.6W/tube
Game plan;
roll PA tubes
change V2 to AX for more gain
bypass V1a some
evaluate
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Why are you using 12AU7s
The AU seems to be better at keeping "too much gain" at bay, the signal comes up better than noise, so less hiss n other related "hi gain" issues.
as long as I can get a drive signal bigger than "bias" to the PA, I'm good.
It sounds like a 5F1 champ as far as loud goes, nice tone, good lows to highs, just not a 10W PP sound like I'd expect from a Gibson skylark kinda amp.
cathode bias P-P stages
you'd need 400V g1 drive with 400V+ B+
lost now;
the datasheet suggests ~ 300 plate, AF peak G-G ~50v (I'm pretty low there), dissipation design center ~ 8+W I'm at 8.6W/tube
Game plan;
roll PA tubes
change V2 to AX for more gain
bypass V1a some
evaluate
when you state unity gain: output = input, IOW a gain of "1".
--pete
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Ya, I'm less than unity PI out to speaker out (13vac out Pi to 5.7 speaker) so that's an issue.
I believe getting more drive to the PA will open it up, but I'll probably bust out the HV probe and see what the PA plates are up to.
and i DID screw up my DCv pa calcs, forgot to subtract Vk from Vp :think1:
once I mess with drive, I do wanna try n bump B+ at plate closer to the 285vdc
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Ya, I'm less than unity PI out to speaker out (13vac out Pi to 5.7 speaker) so that's an issue.
How is that an issue? The power amp ain't about voltage gain. It's about converting voltage to current. 5.7V on an 8Ω load produces .7A and that is 4 watts. That's the important stuff.
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That's the important stuff.
:laugh:
I'm still learning Yoda :icon_biggrin:
made V2 an AX7, got a good bump out, well above what I need to drive the PA with 14.5v bias. more a yawn bump at speaker as to loudness
starting to discern a kinda reverb, empty room "echo-y" sound. the spectrum shows a couple IM signatures (in red) :dontknow:
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what are DCV measurements at pin1 & pin3 of 12AU7 V3A cathodyne?
IMD may PS related - try 100nF node D to GND, may or may not help.
--pete
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:happy1:
I caught a snore bug, then;
replaced the 1K, 1st tap R, with 750, dialed plate right at datasheet 286vdc
Rk might need a tweak, but for now running 9.2W/ tube.
swapped in 2 other PA tubes and changed speaker cabs and the amp IS alive!
much closer to what I was expecting. Pam's watching B&W movies so.......real sound test in AM.
Pete, the plate is 156vdc, the cathode 125vdc
probably scope it out once more and re-do vdc's since I changed the PS rail, I'll glue in another 47uF also.
-
just yawn changes with vdc, shows AX gain bump at V2 n right.
probably done for the night, the AM i'll play awhile, then tweak bypass caps, maybe test NFB although I'm not pushing to distorting and I have no gain to give up, yet.
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stuff a 1K under the cathode of V2B (cathodyne) to bias it proper. Vk is too high.
--pete
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:laugh:
I started playing with paint, but it's noted on schematic, thanks.
got 10 more minutes guitar in, it's there, 90% sure the cab did it. still needs 20% more loud, but that can be had with 6V6's, but I like a challenge :icon_biggrin:
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Ok Pete, I put the 1k in, you do know where it was right, down in the bilge room, way at the bottom, under lots of stuff!! :laugh:
for fun I changed my speaker DL from 8 to 14, Volts at DL went from 8.3VacRms to 10. Next I'll re-config my cab from 8 to 16ohm and play some.
Ready for help with new roach for my TON then I can call the build a success :icon_biggrin:
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I tried it, and liked it! V1 is now an AX7. I lost some sparkle, but the 90's grunge/hard rock came alive!!
ordered the proper vactrol, even went with new old stock, also a 2nd 6V6 for even more bark!
musician/design question, this amp really doesn't like single pickups, but the bridge dual pickups really makes it happy. Is that a "hot" pickup thing :dontknow:
(It is a cheap guitar :)
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musician/design question, this amp really doesn't like single pickups, but the bridge dual pickups really makes it happy. Is that a "hot" pickup thing :dontknow:
(It is a cheap guitar :)
Yes...in some cases more output V from the pickup = more better. Those dual pickups are called humbuckers and almost always have more oomph.
As a player (hack), I have found that I prefer a lowered B+ in V1 because I don't play clean enough to like/need hi-fi response at the input stage. One of my favorite dirty input stages used a low B+ and split load where the signal was tapped off the middle as an experiment....that wound up feeling like home to me. Add some sweet humbuckers to that and viola, plenty of room to hide. Plug singles into that stage and it sounds anemic.
You'll see a lot of old washed up strat players using a boost pedal for those whimpy little single pickups. It's usually to overcompensate for something else....
One of the old tricks of the trade mods was to double(and more) the plate load on V1(leaving all else the same). This makes some voltage gain but also pushes the bias point and makes the stage more likely to clip - some guys like that. V1 obviously has a lot to do with how the amp feels with different pickup types.
More than you asked for but I know you like food for thought.
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I know you like food for thought.
Thanks SG, ya, regular food isn't my thing :laugh:
and I'm finding V1 IS the "key" to keeping things simple AND getting "that sound"
the 6K6 is a great sounder, the problem, drive is almost 2X a 6V6, so as soon as you roll off volume for those teary eyed guitar sounds, the amp just goes yawn n the pretty girls go home with the drummer :icon_biggrin:
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One more morsel while I'm donating.
Have you tried bootstrapping V2a with V2b?
I know it sounds silly to use a low mu tube and then bootstrap it for more gain but it's never been beyond you to be silly.
Thanks to Merlin for the snip:
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all my latest builds use the straight DCCF. I did try the bootstrapped version awile back but I drew it up wrong, fortunately Sluckey caught it, N slapped my hand :laugh:
the DCCF is where I try and get enough gain boost to get my "pre-amp distortion".
V1 I try and get the "mojo". I also want enough signal to spank the PA into being part of the "mojo" crowd, wait, can I still say crowd :icon_biggrin:
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Here's a pic showing where I would connect the TON circuit. May need a 250K or higher INT pot.
BTW, what is your reasoning for using a low Z cathode follower to drive a very high Z cathodyne? V2A plate is very capable of driving that cathodyne. Not logical to me.
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what is your reasoning
simple epic fail on my part :laugh:
I worked on the design over many months and many states and simply didn't double-check, the up-side, it sounds better than my last build!, I love a happy mistake :icon_biggrin:
Same fail with the TON. I did go back and found the thread by Trox on trem in a SE build, Tubenit gave an example of inserting it where I have it drawn, since his build and mine are both self biased PP not fixed, looked good, "cut-paste" here we are :laugh:
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when I scoped this out the 1st time, my thought was she's clean enough to do audio if guitar sucks. I rolled the AU's back in, plugged in my "test tape" and it beats my SS monoblock!!! The pauses are silent, my hearing is ZERO above 12k so can't call that part, the fidelity is real transparent, the only "cork-sniff" complaint; there is a very subtle "hall effect EQ" but on all the songs it didn't take anything away.
throw in the AX's and jamb to Pearl Jam :laugh: win/win
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Here's a pic showing
I was gonna "walk" a .0047uf in place of the .01uf's to see if I could shave a tad bass in guitar mode. Any problem just adding another .01uf at that junction, kill 2 birds :dontknow:
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Use whatever values you like. But you gotta use two caps, one to block voltage from the CF, and the other to block dc from the PI.
-
soldered in LED, lights, no flash. Current vdc on schematic.
1st passed didn't find wiring error, back for 2nd pass soon.
guessing B+ might be to low, so If I don't find wire error, i'll move tap to A, ~340vdc
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Two things...
The 1M resistor under the speed pot should be 100K.
A 12AU7 does not have enough gain to work in this circuit. Change to 12AX7, or, if you want to keep the low gain 12AU7 in the cathodyne position, change to a 12DW7 tube. That way you have a low gain triode for the cathodyne and a high gain triode for the oscillator.
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I can just swap the AX from V2 into V3 and make V2 an AU for now, slipping the decimal also :laugh:
thanks
dave
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alive, still waiting for the posthuman to do Her part, email says by Friday
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So you not gonna perform a photocell-otomy on that Fender roach? Real easy to put it back together if it doesn't act like you want. That photocell ain't picky about where it's light comes from. Marry it to your red LED while waiting for the postman. There was another forum member that successfully did this for the TON.
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photocell-otomy on that Fender roach
:laugh:
I'm assuming it's fine, I just used it wrong.
gonna re-do DV and AC bench checks since I got 10hrs on the tubes and I noted Bias drifted up.
Something I should know but.....
Since I'm self biased PP A1, am I "ok" running close/over to max diss, instead of the "60%" fixed guideline :dontknow:
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Yes, most all cat biased amps run 90-110%.
-
thanks, I was wobbly on PP :icon_biggrin:
It's too nice a day to be inside and Pam's home wounded from moving the large among us
so the amp might get a couple days rest :icon_biggrin:
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I'm such an addict :think1:
9 gator-clips, 2 ecaps and 2 meters, don't get any better :icon_biggrin:
Thanks DL, I put 100uf at tap A and another at tap D, tamed the ripple so I'm happy. I was never "out of spec", but the "swing" was end-to-end of my "spec"
now the fluke gets bored
~ 7.8mV AC at tap D, ~ 2V at tap A.
so caps on order, threw in 2 1X/10X reasonable priced scope probes since I only have 1 left +HV probe
the snow blower did make it to it's summer home :laugh:
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> the snow blower did make it to it's summer home
I did that, and now it snows every day.
Enough for kids to make snowmen.
Mostly melts by noon.
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now it snows every day.
ya, had that last week, last gasp winter, Every spring indicator is here now sans swallows and hummingbirds, but they always sleep in :laugh:
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found 10minutes and put in the roach, results not good. well marked so got the LED in correct. here's a scope shot from top of LED, I was on the 20mV scale 1X and it's to low for the digital to guess at values. Freq setting about where I expected.
since I got way more IC opto's than i'll ever use now, might BB up one on a battery n experiment but got life getting in the way for the next day or so.
-
Use your 87V to check the AC voltage and frequency at the plate of the oscillator tube. First set the freq to 5Hz with the speed pot. Then check the ACrms voltage. Should be about 100VACrms. What have you?
-
with fluke;
5.38hz (range ~3hz - 17hz)
Min 70vac
max 76 vac
avg 73vac
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And what is the dc voltage on the cathode of the tube?
-
with roach, 1.46, when I had the redled, was 1.65
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Is your roach a VTL5C1?
One more check with the 87V... Disconnect the VTL5C1 from the INT pot. Measure resistance of the VTL5C1 dangling leg and chassis. It will be changing so set the speed pot to slow and use the MIN-MAX feature on the meter. What have you? Only interested in min/max numbers.
-
Is your roach
yep, antique radio, NOS
max 2.7M (drifts UP, about 1once in 30 seconds by 10K or so, 1st Max was ~1.6M)
Min 72k
NOTE:
after ~ 8minutes, quit ranging and settled at 3.4M Min stayed happy
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Everything appears to be working. Now use a gator clip and connect the dangling leg of the VTL5C1 DIRECTLY to the circuit as indicated in this pic (not using the INT pot yet. You do have the two caps in place, right? Report back.
DO NOT CONNECT THE VTL5C1 TO ANY DC VOLTAGE!!!
If you don't get a strong trem effect then move the gator clip to V2 pin 2. Report back.
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held my hand all the way! :laugh:
trem is strong, freq varies, swamp works.
probably bad shielded cable. I'm out for the afternoon mostly, thanks.
Nother oddity NFB, was playing with it earlier, with the 39k engaged, I get a "cleaner, small gain boost" and sounds nice, when the 680 ohm engaged, screams
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OK. Now connect the VTL5C1 back to the wiper of the INT pot and connect the top of the INT pot to the circuit. Ground the bottom of the INT pot. What have you?
-
I'm beginning to think this amp is cursed
:w2:
ok, here's my testing;
Wired per snippit;
No guitar sound
.4ohm from injection point to ground
Verified cable and pot good disconnected from circuit
Wired back up, same .4ohm
Installed new pot, same
Resistor side of opto infinity to ground
Original pot 100kRa
2nd pot 500kL
Disconnected, guitar sounds
Opto jumpered as before works as before
Oddity;
No power, in circuit, pot disconnected from incretion point, connected to opto and ground;
pot read 0-120k – 0, out of circuit 0 – 500k
who needs an int pot :laugh:
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3rd pot's a charm!
first 2 were new, Cmade, test good outta circuit.
I have a 1M L beat up radioshack, works fine in circuit, but only from ~.9M to 1M
anything less and trem either quits, or guitar just overwhelms it.
It's time for some AMERICAN HOMEGROWN POTentiometer :icon_biggrin:
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did a AC trace for some wonky, but not bad sounds, found problem, not resolving tonight :icon_biggrin:
big wave is plate of cathodyne, small input.
Big R's in morning :laugh:
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Waiting for the Sun I went back and looked;
when I went to AX in the PI I had girlfriend looking wave, now, gramma looking.
The only changes;
1k under cathode of PI, and cut input cap feeding PI from .01uF to .005uF
anyone got a sense about that before I try n "fix" something that wasn't broke :dontknow:
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What's the status of the tremolo?
-
I have a 1M L beat up radioshack, works fine in circuit, but only from ~.9M to 1M anything less and trem either quits, or guitar just overwhelms it.
This "tells me" any "loading" messes with signal/trem, passed my paygrade to get if it's an impedance thing, insertion location,.......
It does work as expected, just over a very short range
(the resistance I'm quoting is from insertion to ground, measured no power after I played and found the pots range)
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clarified gibberish;
pots 1 & 2 and shielded wire removed, verified outside circuit to be good. There had to be a fail somewhere that I missed.
Pot 3 1M l measures consistent .98M to ground at insertion point.
Pot3 wiper to ground;
at .98M, strong trem, strong guitar
at .91M, no trem (sound), strong guitar
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Disconnect the INT pot. Use a gator clip to connect a 47K from ground to the insertion point. Do you still have enough guitar signal to be useful? If so, use a 50K pot.
-
connect a 47K from ground to the insertion point
that's where I was heading next.
Gave up on "why", added 10_edit_K Gstoppers to the PA tubes, added a 470k Gstopper into PI. (Thanks DL:)
signal path is as good as it's gonna get. The gain pots need tweaking since range for "good signal" 0 - 5, past 5 things distort up in a not so good sound. Difference at speaker power wise is minimal
pic 1 after Gstoppers
Pic 2 max clean PI in, Speaker out
pic 3 Max usable, same points as pic 2
-
still have enough guitar signal to be useful
here's the data;
Baseline, nothing at insertion point to ground, (all #'s Vacrms)
in 38.6 out 39
470K to ground
38.5 39
100K to ground
38.3 38.3 (starting to "load" signal, slight distortion top n bottom lobes)
56k to ground
36.8 35.4 (heavier "loading" on lobes)
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OK. Leave the 56K connected and also connect the opto dangling leg to the insertion point. This is the same as having a 50K int pot set to max. How is the trem effect? Put your scope down and plug in a guitar. I want to know what your ears think.
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was doing this when you called; :laugh:
hunted down a 100k, verified, installed, and I got 1K to ground at insertion :cussing:
roach reads 1K to ground :cussing:
powered up, roach danced the fluke, but only "around" 1K :cussing:
Never been much of a quitter, but this might be a good time to practice :icon_biggrin:
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How the hell do you put a 100K between the insertion point that I suggested and ground and then measure 1K. Not likely in my world.
I ask for a 47K to ground but you show me a bunch of data using various resistors, one being 56K. OK, that's pretty close to 47K. Then I ask for you to leave the 56K in and also connect the opto to the insertion point. But you connect a 100K!!! We sure ain't communicating.
Show me some pics of this amp! No scope traces please.
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I ask for a 47K to ground
we're on the same page,
I wanted to know what NO trem value was, 1st measure.
Since I had 1M pot that worked, I started there and went backward to 47K. (56k, called that one close and quit looking)
The problem is the roach resistance keeps changing.
last night I played, it trem'd like I expected with the 1M pot.
The roach ohmed infinite 2 or 3 times during testing
The roach ohmed 1K 2 times during testing
EVERY time I ohmed the roach the "wiper" wire was disconnected, amp off.
I have 2 NEW roaches and 3 NEW pots on order.
we can both use the break while parts are coming :laugh:
If the roach is supposed to be 1k to ground, or it's irrelevant then I'm game for whatever.
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You've proven that the TON circuit is functioning. Now all you gotta do is experiment to find the right interface. Just keep experimenting, you'll get it.
Here's a variation of the interface that a guy over on TAG used. His trem sounds phenomenal.
(https://ampgarage.com/forum/download/file.php?id=56644&mode=view)
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Just keep experimenting
:laugh:
once I learned to solder, I learnt 60hz was audible and I had a power cord and speaker :icon_biggrin:
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Any progress?
-
:laugh:
No parts yet, but I'm playing better.
This thing is really a nice one for noodling on, fixed the NFB, just subtle differences to me, same with the tone knobs, but I'm not a knob fiddler.
The Gov won't let me n my brother fish in the same boat, so getting parts past the check points might be iffy :icon_biggrin:
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The Gov won't let me n my brother fish in the same boat...
i thought alcohol kills corona?? if that's true, i don't see how that's an issue as long as you're getting seriously hammered when you're fishing. did i miss something?
--pete
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did i miss something?
:l2:
You'll need ALOT to understand this edict!
"No more than 2 related persons per boat, same address"
I don't live with my brother so I get thrown overboard :icon_biggrin:
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new roach in, trem works as designed, but INT pot (100k) is only good from 7-10.
so gonna re-wire like the bandmaster final with the 10k cathode R and FS toggling the LED, and a 50K int and evaluate.
but I smoked my brakes NOT smoking a dog, so 2 blown lines and a complete bleed-down and it's back to early march temps :cussing:
-
Buick on hold so I soldered up the Proper parts and it Trems well, good range, nice sounds for a hack wanna-be. marking up the schematic, callin it DONE :m17
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Whew! Ya'll was wearing me out :think1: Glad that's solved. I know what it feels like to want to give up on something but it's quite a victory once you get there. Ya Haw!!! :happy1:
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Ya'll was wearing me out
I'm already washed up, worn out, but I can still crawl :laugh:
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i thought alcohol kills corona??
I have a bottle of corona dope. Unfortunately it dried up several years ago. :cry:
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:laugh:
was cleaning up random junk in the barn, found a jar of instant coffee from the '90s, paused while I though, hmm If the world melts.... Pitched it.
Found a random baggie, probably the same time-frame, laughed since I can buy that as essential product :think1:
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> corona dope. Unfortunately it dried up several years ago.
Just the solvent/spirit. Try a cocktail like this:
Toluene 108-88-3 70.0 %
Ethyl Alcohol Denatured 64-17-5 10.0 %
2-Butanone (MEK) 78-93-3 5.0 %
Methyl Isobutyl Ketone 108-10-1 5.0 %
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ok, pleading ignorance, I had lots of corona balls in my equipment, but never cleaned with corona dope, just alcohol :dontknow:
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Silly you. Corona dope ain't for cleaning. :icon_biggrin:
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ok, sent the ducks, they got confused!
guessing it's the "finger nail polish" for coating wires, not the dielectric grease I put on the anode/cathode of X-ray tubes before seating them? that was pure HiVolt silicon
didn't even bother with guitar cleaning product link
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https://www.skygeek.com/gc-electronics-10-5002-red-x-corona-dope-2-fl-oz-bottle-8040-00-779-2863.html
https://www.circuitspecialists.com/4226-55ml.html
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found the 2nd stuff, had this comment;
Insulates components circuits and assemblies
"tells" me it's the hard or rubbery crap I had to dremel off boards to get to the failed parts :dontknow:
always "assumed" that to be and enamel or urethane "stuff" meant to Pi..OFF guys like me when we got a little to cocky :icon_biggrin:
In the Civie world mostly "moved up" to board swaps since time/money was way more important than it was in Gov'mt work :laugh:
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Just when you though I was gone :icon_biggrin:
Version II
put in 6V6's, changed bias to single R&C, moved the OT CT to A tap
idling at 13W a tube, 11.7W a tube at full on.
picked up enough speaker loud that it's comparable to my SE KT88.
that's next, both amps together :icon_biggrin: