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120V LED vs. 6.3V lamp: Pros / Cons?

Discussion in 'Shock Brother's DIY Amps' started by King Fan, Jan 20, 2021.

  1. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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    When I was building my bucking transformer, I ended up with an extra LED indicator light -- the kind that runs on 120VAC. OTOH in my amps I've always used the traditional Fender 6.3V incandescent lamp.

    Other than style points, are there advantages of one over the other? Or downsides to consider?
     
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  2. Pick_n_Strum

    Pick_n_Strum Tele-Meister

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    Interesting, didn't know that existed. They must have a diode and current limiting resistor built-in, right?

    Sorry, I don't have a direct response to your question. I usually go by price and ease of install. I have a standard LED in a D-style build that I really like. It was obviously cheap and easy to put in because the relays already had to have DC to them, so it's just tapped off that.
     
  3. Nickfl

    Nickfl Friend of Leo's

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    The only thing I can think of is a small point against the incandescent in that it adds a little bit more current draw to your PT heater winding, so dropping it in favor of the 120 volt indicator on the primary side of the transformer would allow your amp to run ever so slightly cooler.

    Personally, I've come to prefer using LED indicators run off of the heater winding. Cheap and easy with a low current draw, it's the best of all worlds if you're drilling your own chassis. If you are using a chassis drilled for a traditional indicator you would have to make some kind of adapter for the hole though and that obviously isn't going to be a great option if you are trying to match a vintage aesthetic.
     
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  4. NTC

    NTC Tele-Meister

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    The diode is built into the name LED - light emitting diode. :D Really just need the appropriate dropping resistor. And lots of insulation material.

    Someone probably makes an led replacement for that 6.3v bulb that goes into the standard socket.
     
  5. Phrygian77

    Phrygian77 Friend of Leo's Gold Supporter

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    Could also increase the heater voltage, not a good thing. Just something to keep in mind.
     
  6. Phrygian77

    Phrygian77 Friend of Leo's Gold Supporter

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    I tried one a few years back. It just doesn't look right in a blackface amp. It was too bright. By the way, that was using a red LED bulb with a red jewel. Trying to use white looks even worse.
     
  7. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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  8. Pick_n_Strum

    Pick_n_Strum Tele-Meister

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    I get that but don't you need at least half-wave rectification? There has to be a diode in there too, other than the LED, right? Not that it matters, just curious.
     
  9. NTC

    NTC Tele-Meister

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    An led really is a diode and only passes current in one direction. That is why people replace the diodes in distortion pedals with LEDs sometimes - the work the same. LEDs have a higher forward voltage than normal signal or rectifier diodes but don't handle as much current unless they are meant for room lighting.
     
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  10. telemnemonics

    telemnemonics Telefied Ad Free Member

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    Is this a new incoming trend?
    I just looked for a bulb a few days ago and have none left, should I stock up on NOS vintage lamps?
     
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  11. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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    I’m not much up on LEDs, but I do know about current limiting resistors on the standard little guys. The indicator light I got is set up to run inline on 120. I just went to Amazon and searched for ‘led indicator lamp 120v.' One of the two looks like this.

    7F1A208C-78F3-4625-B614-25B7C8CB96B5.png
     
  12. NTC

    NTC Tele-Meister

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    Stocking up on vintage lamps is not out of the question...

    Of course, your amp will sound better with NOS lamps than with those new ones.
     
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  13. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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    LOL, I sure wouldn't run one on a vintage-style Fender amp. OTOH, I went through a phase when I started where I had to have every color of jewel light -- so cool, don't ya know. Now I'm just on red.

    If you built an amp in a non-vintage form factor, though, say a silver or black Hammond chassis, a plain indicator lamp might actually be more 'in keeping.' Oh, and the kind I'm talking about isn't too bright. Here's my 'brown box' bucking transformer.

    VVA - 2 (1).jpeg
     
  14. alnico357

    alnico357 Tele-Afflicted

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    I put an LED in my DRRI instead of the standard bulb. The main reason was the flimsy bulb holder. It bends extremely easily. I wanted to put an LED in and be done with it. So far so good after 10 years.

    I put in a white one and change jewels out now and then.
     
  15. Peegoo

    Peegoo Poster Extraordinaire

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    The only requirement is that the LED can handle the current. Since an LED lights only on forward voltage, it's lit during half the AC sine wave--meaning it blinks at the frequency of your AC mains voltage (50 or 60 Hz).

    You can run pretty much any LED on mains voltage so long as you limit the current with a resistor of the proper value & wattage dissipation rating.
     
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  16. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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    Aha, I see what I found on Amazon is *not* an LED, despite having LED in my search term. When you read the fine print (scroll about a yard down on Amazon) they note mine is a *neon* lamp. So is the other one I got from Doug Hoffman, which looks like this. Doug's listing is clear, though.

    upload_2021-1-20_21-22-19.jpeg

    Still, you certainly can get 120V indicators that *are* LED; here are the first eight hits I got with the term "LED indicator lamp 120V."

    upload_2021-1-20_21-31-43.jpeg
     
  17. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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    So looking beyond the (ahem) incorrect and misleading thread title, I guess the question is if there's an advantage to showing the heater circuit is live instead of just the AC power / fuse / switch. I'm gonna guess that advantage is pretty darn small. If so, and we ignore the 120 lamp's very slight reduction in current draw on the PT, or very slight increase in heater voltage, it's down to style points.

    Oh, and I guess we could add one other tiny difference -- every once in a while an incandescent bulb will burn out. Do LEDs? Well, ± no, right. My neon lamps? Who knows.
     
  18. Tom Kamphuys

    Tom Kamphuys Tele-Holic

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    Using the led, you can keep the (high current and magnetic field) heater wiring shorter, hopefully limiting hum. Electric fields from the 120V are more easily shielded.

    Screenshot_20210121-162600.png
     
    Last edited: Jan 21, 2021
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  19. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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    Good point, the extra 6.3 wiring run actually got me thinking about this.

    But that amp is built so beautifully I'm thinking EMR has no place to hide. :)
     
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