LED instead of traditional Fender Lamp

[samato]

Probably a dumb question but are there any disadvantages to using one of the LEDs listed here instead of the standard Fender type lamp assembly for a pilot light?

http://www.hoffmanamps.com/MyStore/catalog/parts20.htm
EDIT: IT IS THE FIRST ITEM ON THE HOFFMAN ONLINE STORE UNDER "LAMPS/DIODES/SWITCHING".

Since I don't really care about looks on this project I thought I would go with the LED as it's cheaper and smaller.  Here's the diagram of the amp I'd be using it on, if that matters.

[sluckey]

Don't forget to use a current limiting resistor.

[Tiny_Daddy]

Those work just fine for a lot of things unless you need a beacon that can be seen from the back row.

[stingray_65]

When I don't use a 6V pilot lamp, I usually use a 120V neon hooked to the mains after the switch.

I prefer this to the 6V fender pilots, but there is a certain look many expect to see in a tube amp.

The neons on the mains are simpler, far more reliable and much cheaper than any other rout I've taken so far.

In fact just yesterday when working on my TOS build, I blew a fuse. I had little landed on board and my HT wasn't connected to anything more than a choke and resistor so I didn't use my current limiter (light bulb).

after pulling my heater wires, 100ohm artificial CT I checked continuity at my heater wires. found out I had a bulb that was made wrong and it was a dead short.

Not to mention the bulbs are hard as heck to get in and out unless you use a pen cap or other instrument, they don't last long at all if you're using vintage iron and your heater V is a bit high. OH and drilling that 3/4" mounting hole is a PITA.

but dang they look cool!

Ray

[samato]

So regardless of whether I use LED, neon, standard bulb - it has nothing to do with anything functional that could in some way affect the sound?  If that's the case I will probably choose neon as it does seem easier.

As I mentioned, looks don't matter unless it's just completely ugly.  If looks were a concern I would go with the standard Fender style bulb.

[FYL]

So regardless of whether I use LED, neon, standard bulb - it has nothing to do with anything functional that could in some way affect the sound?

Neons can be quite noisy but aren't usually a problem when located away from sensitive circuits (inputs, grid leads, reverb recovery, etc.).

[tubenit]

Having had amps with both Fender style and LED lights, ..... every build I have done has had the LED lights that Hoffman sells & I prefer that because they take up waaaayyyyy less space. I've had zero problem with LED lights.

With respect, Tubenit

[samato]

Ah, one report of noise with neon & one report of zero problems with LED.  Thanks guys.

[Fresh_Start]

I read dire warnings LEDs about powered by the heater supply flickering on two other forums.  Noboby has that problem?  Exactly how are you all wiring the LED indicators?

Thanks,

Chip

[stingray_65]

When I do run LEDs I make a little 5V regulated PS using a FWBR and a 7805 chip. a few small filter caps and your good to go.

the FWBR tapped into the heaters yields about 8VDC rectified which is perfect for the chip.

It will power many 5V relays too.

Ive built this on a proto board and it's smaller than a quarter. I've also turret mounted it ,but its much larger.
Ray

[tubenit]

I read dire warnings LEDs about powered by the heater supply flickering on two other forums.  Noboby has that problem?  Exactly how are you all wiring the LED indicators?

I've never read anything about dire or any other kind of warnings.  I've used them on every amp I've built with NO issues. Just did them like Hoffman shows in the parts catalogue.  I guess if someone did not have a solid solder joint or a wire was shorting on something ............. maybe  that would cause it.  I wire mine up and use shrink tubing around it.   I've always used the 6.3v heater wiring.

With respect, Tubenit

[PRR]

Yeah, AC-powered LEDs flicker. So what?

And FWIW, my new electric blanket's LEDs flicker.

If you hold your head steady, you don't see flicker.

If you move, you get the STROBE effect that was so popular in 1969 (maybe still is; I don't go to those places any more).

Don't you have something better to fret about?

[samato]

If the rest of the amp is fine and the LED flickers, I couldn't care less. 

That is what we're talking about right?  It's not that the flickering LED also results in a fluctuation of voltage or anything, is it?

[jojokeo]

I've seen the dc reg supply but those take too many parts (unless relays or other stuff is needed also). I simply use the 117v and it only requires the LED itself, a 1K 1/2w resistor, a diode, and a .047/200v cap. That's it and works like a charm.

I forgot to mention, if you're going for max gain on a stage at all frequencies, use an LED w/ a .1uF/100v cap across it (to minimize noise) in place of the cathode resistor/cap. It will light up and serve as a dual purpose indicator light too.

[samato]

Uh, I'm more confused than ever now.  I think I'd better just go with the standard lamp used in the original design. 

[jojokeo]

Use the upper left one. Instead of the 1N914 you can use any 1N200_ diode - these are simple standard diodes. The 2nd ex shows using two LEDs. Other than this it's only a resistor and capacitor.

[phsyconoodler]

I just added an LED as a pilot in my latest Overdrive Rocket.I simply used a lead off the relay DC supply and used a dropping resistor in-line.It works fine.
  I kind of like the idea of a flickering pilot.Especially if you hook it up to a trem circuit.
Mesmerize your audience and play some cool tunes.
  

[Fresh_Start]

Well, my next build should have a non-flickering LED standby indicator... if everything works according to plan. (see below)  I'll post results if they are good

Chip

[phsyconoodler]

If you use AC it might flicker.Not so with DC.

Just curious on the LED specs for the AC one.

[jojokeo]

Using the heater taps it should only require two diodes, an LED, and the dropping resistor. No need or reason to use a FWB rectifier, voltage regulator, or capacitor. Four parts, cheap and really easy.

I would suggest using the super bright ones. I've used the normal ones and they can be a little hard to see at an angle or during the day.

[EL34]

I have used that LED on my web site and a 180 ohm resistor in 100's of amps, preamps, rack units and  pedals
Every one is still running and nothing flickers.
You can run a LED on AC just fine, it does not require any other components to work.

Not sure how or where all these weird rumors get started??

By the way, the links you should copy and paste are at the top of the forum
http://www.hoffmanamps.com/MyStore/catalog/parts20.htm

[samato]

I have used that LED on my web site and a 180 ohm resistor in 100's of amps, preamps, rack units and  pedals
Every one is still running and nothing flickers.
You can run a LED on AC just fine, it does not require any other components to work.

Not sure how or where all these weird rumors get started??

By the way, the links you should copy and paste are at the top of the forum
http://www.hoffmanamps.com/MyStore/catalog/parts20.htm

That is good to know.  As soon as I read about noise and needing to use diodes, capacitors, etc. I lost interest in using the LED. 

I saw in the item description that a resistor is required and if that's all there is to it I'm okay with that.

[Fresh_Start]

I have used that LED on my web site and a 180 ohm resistor in 100's of amps, preamps, rack units and  pedals
Every one is still running and nothing flickers.
You can run a LED on AC just fine, it does not require any other components to work.

Not sure how or where all these weird rumors get started??

By the way, the links you should copy and paste are at the top of the forum
http://www.hoffmanamps.com/MyStore/catalog/parts20.htm

Several folks on the AX84 forum insisted that an LED powered off the 6.3 volt heater supply would flicker and be very annoying.  Same thing over on AMPAGE.  Maybe they're staring at their LEDs under black light???

This is NOT to doubt you Oh, Alien Being!   Just wanted to answer your question.

Cheers,

Chip

[Boots Deville]

I'm with the Aliens, I routinely run 'em right off the 6.3V supply with a 470R resistor in series, and never see a flicker.

Those work just fine for a lot of things unless you need a beacon that can be seen from the back row.

In the attached picture I'm the guy with the Gretsch, behind me is my amp with the bright blue LED beacon shining thru the fog.  On the right of the big bass player you can see another one of my builds, the orange amp, which has a standard fender type jewel light.  The jewel is blue, although it looks white in the picture. 

I mount the LEDs in a chrome bezel, so maybe that helps them shine brighter, I dunno...

[samato]

How bright the thing is and whether or not it flickers is of no concern to me although it's good to know I guess.  I just want to know if they cause any operational problems.  It appears that question has been answered.  Thanks for all the replies.

[EL34]

Maybe the people that have flickers don't know how to intstall things properly.  
Maybe they are over driving the LED's, hard to say.

Not sure how you can even get flicker unless you have bad solder joints
Even if the LED did flicker at 60 cycles a second, would it be enough to see while you were drinking a beer and playing your guitar.

[jojokeo]

LED running on AC clarification needed. I've never ran them like this but wanted to test a few out. I have a few superbright deep red LEDs w/ a Fv = 1.86v
So 120v-1.86=118.14v, 118.4/.02= ~5907r
#1) I have 6k/10w resistor and hook it up w/ test leads to 120v ac and the power resistor gets hot. Circuit should only run at 118.1x.02A= 2.4watts but why does the resistor get so hot? IS this running at doube the current going through LED because of AC being used (but my meter didn't show this while in-line w/ circuit)?

#2) Then, I also tested a green superbright LED w/ slightly higher Fv and I think it got too hot even though it's still in plenty of safe range w/ the power resistor and it worked at first but then only intermittently  , then I read where LEDs can be sensitive to leads being stressed. Even though I've never had this problem, I did have to bend the legs for the alligator clips not to short. Did this happen from too much heat and/or stress on it's leads?

I've not hooked up many superbright LEDs vs regular LEDs as the regular LEDs seem much less sensitive than the superbrights from this quick experiment. Please "shed some light" on this for me (pun intended).
Thanks-

[sluckey]

There's another LED parameter that you probably should not ignore. An LED is a diode and it has a PIV (peak inverse voltage) rating. 120V_rms is 170V_peak. You can get around this by putting a 1N4007 in series with the LED. I'd be very uneasy about connecting a flimsy LED to 120V.

That 6K resistor will dissipate 2.5 watts if connected directly across the 120V line so you're safe, but I'd expect that to be hot.

[jojokeo]

Thank you Sluckey for reminding of the PIV rating. I normally hook them up as I've posted/described earlier in this thread and it works like a charm. I take it that this issue is of no concern w/ the 6.3vac since the voltage is much lower as Doug says to do?

[sluckey]

6.3vac would be much safer to work with (for you and the LED). Those circuits you posted above all look good. They all have reverse voltage protection too.

[Merlin]

Circuit should only run at 118.1x.02A= 2.4watts but why does the resistor get so hot?

2.4 watts IS hot! Damn hot when handled by a small component like a resistor. People get round this by using a capacitor to reduce the current to the LED instead (plus a small resistor to limit inrush current).

[jojokeo]

Circuit should only run at 118.1x.02A= 2.4watts but why does the resistor get so hot?

2.4 watts IS hot! Damn hot when handles by a small component like a resistor. People get round this by using a capacitor to reduce the current to the LED instead (plus a small resistor to limit inrush current).

I understand and is why I used a 10w resistor - having 4 times the rating needed.

I normally use the cap, resistor, and diode as in the schem earlier I posted, but tried something different after Doug's comments figuring I give it a go a couple nights ago after mowing the lawn, putting out the trash, etc. and having a cold one. I didn't really think everything through enough and wanted to do a couple quick and dirty tests while it was on my mind. 

[EL34]

I would not hook the LED up to the mains!!!

Why do that when you already have a great low voltage source in the heater supply.

BTW, I just wrote a cool php program the other day that can tell you what the current limitr resitor value should be
It can also tell you what current you will be running by the value of the cirrent limit resistot

see this page
http://www.el34world.com/php/LedCurrent.htm

[Fresh_Start]

I would not hook the LED up to the mains!!!

Why do that when you already have a great low voltage source in the heater supply.

BTW, I just wrote a cool php program the other day that can tell you what the current limitr resitor value should be
It can also tell you what current you will be running by the value of the cirrent limit resistot

see this page
http://www.el34world.com/php/LedCurrent.htm

Cool! Thanks.

[PRR]

> Maybe the people that have flickers don't know how to intstall things properly. 
Not sure how you can even get flicker unless you have bad solder joints
Even if the LED did flicker at 60 cycles a second, would it be enough to see while you were drinking a beer and playing your guitar.

I don't do beer -OR- bad joints these days.

The 6V AC heater winding goes from zero to positive to zero to negative and back 60 times a second. The LED is "on" ONLY when the voltage is Positive and higher than 1.6V-2.3v. i.e. less than half the time.

FWIW, a Neon also flickers. But it lights when the 120V AC is over 90V _either_ way. Still about half the time, but twice as often.

Wire a red LED and a 330-1K resistor across a 6.3V AC supply. Look at it. It looks steady. Now turn off the room lights and move your head quickly. You don't see a "strobe"?? Is it just me and my chemical brain damage? Am I hallucinating a strobe-flicker?

> red LEDs ... to 120v ac

NO!! That's really really dangerous, reckless, and wasteful.

For the several Watts you are dissipating, you could get a dang 230V 15W incandescent lamp, run on 120V, get long life, a deep-red glow, and over a lot more area than an LED will get. And no silly-state parts. (Or is it now hard to find 15W incandescents?)