Add a power light?

AllanMarcus · 1928

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Offline AllanMarcus

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on: August 28, 2018, 04:49:25 PM
I keep leaving my dang amp on. I'm getting old. Hell, I may actually be old! Please define old? :-)

At any rate, any ideas, pros, cons, on adding an LED power light? Obviously I don't want it to affect the sound at all. Maybe a drop in replacement for the power switch? Or a replacement with a little cutting?

Maybe this one?
https://www.waytekwire.com/item/44206/Carling-LT-1511-110-012-Clear-Nylon/

Data Sheet
http://www.carlingtech.com/sites/default/files/documents/LT-Series_Details_%26_COS.pdf

Or this one?
https://www.jameco.com/z/103-0003-EVX-Mountain-Switch-SPST-ON-OFF-Standard-Toggle-Switch_2266775.html

These switches assume 12V DC. What's running through the power switch on the Mainline?
« Last Edit: August 28, 2018, 05:23:18 PM by AllanMarcus »

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Offline Paul Birkeland

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Reply #1 on: August 28, 2018, 06:07:04 PM
There's no source for 12V in the Mainline; the power switch is switching your AC line voltage (120V or 230V, depending on where you're located).

6C45PI tubes last a long time, leaving them on overnight here and there isn't the end of the world.  The little glowing dots on the 12AU7 should be pretty visible.  If not, you could put a clear top 12AU7 in the middle socket for better illumination.

Paul "PB" Birkeland

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Offline AllanMarcus

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Reply #2 on: August 28, 2018, 06:13:38 PM
Thanks. The glow from the 12AU7 is pretty dim, and amp is shaded! Getting a clear top looks to be pretty cheap, so I might try that.

Maybe I need a tube socket with an LED like McIntosh has!

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Offline Paul Birkeland

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Reply #3 on: August 28, 2018, 06:22:55 PM
The LED in the socket is actually not that hard to do.  There's +6.3V on pins 4/5 and the ground for that +6.3V on pin 9 of the 12AU7 socket.  Most leaded LEDs that you find at the electronics surplus shop will light pretty adequately with 2mA or so of current and LED voltages are going to be a couple of volts.  A 2K resistor in series with the LED should be adequate for current limiting (resistor wattage isn't important here, use the smallest one you can find).

You can glue the LED to the little center hole in the 9 pin socket with silicone RTV from the auto parts store (DO NOT use bathroom or construction silicone, it will damage your kit).


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Offline AllanMarcus

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Reply #4 on: August 28, 2018, 06:53:35 PM
Thanks Paul!

I was thinking I could punch a hole near the power switch and mount a little LED indicator light, and power it from the 12AU7 socket as you suggest. It would mean running a little hookup wire under the plate from the center socket to the left front of the amp. Do you think that wire might use any interference?

Alternatively, I might just put the LED under one of the vents and see if that is enough to catch my eye. I just wonder about any sonic implications.

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Offline Paul Birkeland

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Reply #5 on: August 29, 2018, 04:38:25 AM
I don't generally recommend drilling extra holes if you can avoid it.  The LED in the socket is pretty easy to remove, as would be an LED that fires out of the vents.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Raymond P.

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Reply #6 on: August 29, 2018, 07:12:03 AM
I have a power strip that connects only to my Mainline and DAC. I use the power strip's switch to turn on/off this combo. The DAC has an LED to indicate power, and I use that to conveniently tell me if the system is on or off. The LED idea sounds like a nice project though.

Raymond P.


Offline Leland Hankins

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Reply #7 on: August 29, 2018, 08:21:49 AM
How about just using an Arcolec USA Number 2950 125V 1/3 W light , just attach the leads to the power switch.  There is plenty of room for a hole.



Offline AllanMarcus

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Reply #8 on: August 29, 2018, 08:59:34 AM
How about just using an Arcolec USA Number 2950 125V 1/3 W light , just attach the leads to the power switch.  There is plenty of room for a hole.

My google-foo isn't up to par for this one. Can you please provide a link?

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Offline Leland Hankins

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Reply #9 on: August 29, 2018, 08:23:37 PM
I have a bundle of 125v (orange) and 12v (green) lights.  They are panel lights for substation/electrical equipment, I have had them for 30+ years.  There has to be a modern day led equivalent panel light for 125v equipment.  If you would like I will put a couple of the 125v lights in an envelope and put them in the mail.  Need your address.



Offline Adrian

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Reply #10 on: August 29, 2018, 11:15:36 PM
Here is link to my post with a 117VAC LED I have installed in several BH kits (not a Mainline, yet).
it is connected after the power switch and in parallel with the supply and primary of the power transformer.
Scroll down for my schematic of the light circuit is and how it can be installed.

https://bottlehead.com/smf/index.php?topic=9518.msg91244#msg91244
« Last Edit: August 29, 2018, 11:17:54 PM by Adrian »

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Offline AllanMarcus

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Reply #11 on: August 30, 2018, 02:42:29 AM
Thanks Leland and Adrian. Good info.  Adrian, what you did on the S.E.X. looks great! I’m gonna try the LED under the 12AU7 first and see if I can get a nice glow there. If that doesn’t work for me, it certainly appears Zoro has a large selection of 120VAC lights to choose from.

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Offline AllanMarcus

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Reply #12 on: August 30, 2018, 05:57:51 PM
Well, I had some leftover LEDs and 220 Ohm resistors from a Pi project, and I tried them, and they worked! The picture shows the "underglow". The room is dark, so it's a little exaggerated, but with normal room lighting (which is on the lower side), I can definitely see it. I think a it might even be more better with a clear top.
« Last Edit: August 30, 2018, 06:01:41 PM by AllanMarcus »

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Offline NightFlight

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Reply #13 on: September 04, 2018, 05:25:57 PM
I just put a little circular sticker by the power switches ON position. Done.

I thought about replacing the power switch with a 115V lit power switch like you see in power bars, but I didn’t want to introduce noise.
« Last Edit: September 04, 2018, 05:29:16 PM by NightFlight »