extra tubes on the 6.3VAC circuit

[AxeAmpTN]

This is probably going to sound very strange, but I have a customer with a custom build request that is essentially a Vibrochamp, but with lots of extra tubes just for looks.  He wants the heating elements to light up, but is NOT interested in using them for the amplifier.

So my question is this:  if I add about 6 more tubes on the 6.3VAC line from a Champ PT, will it put added strain on the actual amplifier circuit?  Or would I be better off adding an extra 6.3V tranny just for that?

[shooter]

you'll be adding ~ 2A ( .3*6)
seems a champ PT might feel the strain.

an alterativealternative  I did, drilled out the socket to accept an LED which shined up into the tube, used it as my power on light 

[AxeAmpTN]

Thanks, shooter.  I have considered the LED idea and may yet propose that to him.  It will be more easily visible anyway.

[shooter]

there's a bunch cheapish of C-made kits that can "pulse to the music", think disco tubes 

[kagliostro]

+1 for Shooter Led idea

Franco

[PRR]

Six 19EZ8 across the 110V line. Cheaper than one more 12AX7.
https://vacuumtubesinc.com/index.php/vacuum-tubes/19ez8.html

[kagliostro]

Ciao PRR

The idea is nice, but this way the 110V line isn't going around the chassis without a galvanic protection ?

---

EDIT:

May be a set of 1R5 tubes (6 or 7 tubes) connected in series to the 6.3V winding ?

1R5 heater = 1.4V @ 0.05A (the load is minimal as they will be in series)



http://www.r-type.org/pdfs/1r5-1.pdf

10 tubes at 10.08€

https://www.esco.it/product_info.php?products_id=1279

Franco

[nandrewjackson]

I would NOT risk burning up a power xformer for that.


LEDs yeah


PRRs idea  yeah.

[AxeAmpTN]

Ciao PRR

The idea is nice, but this way the 110V line isn't going around the chassis without a galvanic protection ?

---

EDIT:

May be a set of 1R5 tubes (6 or 7 tubes) connected in series to the 6.3V winding ?

1R5 heater = 1.4V @ 0.05A (the load is minimal as they will be in series)



http://www.r-type.org/pdfs/1r5-1.pdf

10 tubes at 10.08€

https://www.esco.it/product_info.php?products_id=1279

Franco

Fascinating ideas, kagliostro and PRR!  I'll explore that a little.  Are either of those tubes' heaters brighter than what you'd find in an average 12AX7?

At the moment, the LED's are probably getting first consideration as there will be the greatest opportunity for interesting lights at a cost effective price point.

[shooter]

the 6 EXTRA tubes will NOT impress a good player, the LEDS might get $2 in the tip jar 
always consider your audience when building 

[PRR]

The battery (1.4V 0.050A) filament tubes' glow is hard to see.

[AxeAmpTN]

the 6 EXTRA tubes will NOT impress a good player, the LEDS might get $2 in the tip jar 
always consider your audience when building 

You're absolutely right, shooter.  But this guy just wants a nice showpiece for home use.  It's actually an old tube-powered EKG machine that he wants turned into a guitar amp.  Since it has a display window for the stylus and paper, he thought it would be cool to see a bunch of glowing tubes inside.  Unfortunately, with limited space and wattage, it's better to have some tubes just for looks (and it already came with 8 or so) and to put in a new circuit for the amp than to try to put the amp tubes where they'll be seen.

[sluckey]

Not many little low current tubes make enough light to be impressive to anyone. You need big bottles to get excited.

However, gas regulators like 0A2, 0B3, OBwan, etc. are really impressive and they don't require any filament supply. Just a series resistor to B+ and you get a nice glow. Should be able to find them pretty cheap too

[kagliostro]

The battery (1.4V 0.050A) filament tubes' glow is hard to see

--

Not many little low current tubes make enough light to be impressive to anyone.

 

..... gas regulators like 0A2, 0B3, OBwan, etc. are really impressive and they don't require any filament supply.

 

--

.... it already came with 8 or so

if you mean tubes (8 tubes) aren't that enough ?


and, other question


if the PT is to be used for a champ (0.3A for preamp + 0.45A for power tube = total 0.75A), assuming those 8 tubes have a consumption of 0.3A each one, you have a total disposable current of 8 x 0.3A = 2.4A


if you subtractminus the consumption of a champ (0.75A) from the disposable current (2.4A) leave you with 1.65A of available current, with that you can feed 5 x 0.3A heater tubes or, a big bottle ..... 6L6 or 807 (I like the 807 aspect)


Can this satisfy the request ?

Franco

[DummyLoad]

impress the girls    4E27/5-125B locate a used/dead one ebay, buy it for the filament - filament supply is 5V @ 7.5A.

use a LED string lites for a faux plate lead. the filament makes a nice night lite.


--pete

[davidwpack]

I did a tube night light with LEDs. Wired them a put them in a pedal box.

[kagliostro]

https://www.youtube.com/watch?v=BZGAXfz874Q

Franco

[AxeAmpTN]

I apologize for not getting back to this sooner.  Thanks for the input and ideas, everyone!

if you mean tubes (8 tubes) aren't that enough ?


and, other question


if the PT is to be used for a champ (0.3A for preamp + 0.45A for power tube = total 0.75A), assuming those 8 tubes have a consumption of 0.3A each one, you have a total disposable current of 8 x 0.3A = 2.4A


if you subtractminus the consumption of a champ (0.75A) from the disposable current (2.4A) leave you with 1.65A of available current, with that you can feed 5 x 0.3A heater tubes or, a big bottle ..... 6L6 or 807 (I like the 807 aspect)


Can this satisfy the request ?

Franco

Franco, the tubes that came in the unit were:
4x 6AQ5
3x 12AX7 (which will probably get reused)
1x 5651
1x 6AS5

Your math makes good sense and may come in handy to get something going here.  But I'm also digging the suggestions for the 0A2, 4E27, and 807 applications...unfortunatly, I'm not very familiar with those.  I was just browsing data sheets about them.

So new question:  what might be the best way to incorporate something like an 0A2 in something like this?  It seems like it will have an impact on the amp circuit, but maybe that's what we want here???

[sluckey]

You already have one of the most popular gas regulator tubes... 5651. Just connect one end of a resistor to B+, the other end of the resistor to the plate, and the cathode to ground. I'd start with a 100K and adjust up/down for a pleasing glow. Do the same for any of the others such as 0A2.

[kagliostro]

3x 12AX7 (which will probably get reused)

as the transformer can handle the current

I will probably extend the reuse also to the 4 x 6AQ5 tubes (after all they are 6V6 in a small envelope)

Franco

[sluckey]

Just for you... I rigged up a 5651 and 220K/.5W resistor and connected it to a 300V B+ node in an amp on my bench. Works very well on 425V also. Maybe this is a visual your friend would like. Only about 1mA current. If you decide to do something like this I suggest creating a separate B+ node that's fed directly from the reservoir cap.

[kagliostro]

If you decide to do something like this I suggest creating a separate B+ node that's fed directly from the reservoir cap.

+1 for Sluckey's separate node to feed the gas tube

Franco

[AxeAmpTN]

Just for you... I rigged up a 5651 and 220K/.5W resistor and connected it to a 300V B+ node in an amp on my bench. Works very well on 425V also. Maybe this is a visual your friend would like. Only about 1mA current. If you decide to do something like this I suggest creating a separate B+ node that's fed directly from the reservoir cap.

Sluckey, that's awesome!  That was one tube I didn't really know about!

Can you define "reservoir cap" for me?  That's not a term I recognize from my usual tube amp work.

[shooter]

Can you define "reservoir cap" for me

filter cap help?   used in PS "chain"

[kagliostro]

Can you define "reservoir cap" for me

First cap on PS in this case (I suppose)

Franco

[sluckey]

Reservoir cap is a term I never used before hanging out on guitar amp forums. It is a term that lots of guitar heads use to identify the first filter cap connected to the rectifier. I personally consider every filter cap as a "reservoir" cap. Anyhow just to be clear I'm referring to the first cap connected to the rectifier, also called Node A, plate supply, etc. My suggestion to make a separate node that is connected to the first filter cap is so your downstream voltages don't change with the additional load of the gas tubes.

Example, the voltage on your first filter cap is 425V. I would connect one end of a 5K 10W resistor to the first filter cap and connect the other end to a new 22µF cap to make a separate filter node. Now use this node to supply as many 5651s as you want (be reasonable here). Don't forget to use a separate series resistor for each tube, ie, four tubes, four resistors.

[AxeAmpTN]

Thank you! That helps!

[ALBATROS1234]

why not get a $10 filament xfrmr i have gotten 6.3v @ 2amp type for that several times then just parallel the primary with your other transformer primary.

[AxeAmpTN]

Hey y'all...I really appreciate everyone's input on this.  I just wanted to follow up to show off a few photos of how it came out. Thanks again!