Pilot Light 'On' addition to Crack

[TubeGuy12]

I'm curious how best to add an led 'on' indicator to the Crack. Yes, tube glow indicates that the amp is on. So, this is redundant. But I'd like to fill the mis-drilled hole that now graces the top-plate (after adding some panasonic film output caps connected via two bolts through the top using zip ties).

I've so far figured out the following: add the led to the 6V heater circuit between a diode and a resistor. Long leg of the led connects to +, short leg to -; diode comes before the led (with diode's cathode side closest to the led's anode side); resistor comes after. Question: from where exactly, and to where exactly, should I make the connections?

Any help would be much appreciated, including suggested diode and resistor values. Maybe I can even learn something along the way.

[Paul Birkeland]

There's no + and - for the heater AC voltage, so nothing to worry about there.  Typically one would opt for an old school pilot lamp that's made to run on AC though. 

There are tens of thousands of LEDs for sale at the large electronics supply houses.  You'll have to figure out what color you want and how bright you want it, then that will narrow down the diode selection and you can see how much current the diode should run to work properly off the datasheet.

[TubeGuy12]

Ah, ac, right. So, no + and -. Many thanks for the reply, Paul.

[Adrian]

I have used an LED light that uses 110VAC and connected it in parallel with the Main Transformer Primary, after the switch.
https://www.zoro.com/value-brand-round-indicator-light-green-120vac-24m050/i/G4705181/
Here is a representation of the light showing it connected in parallel with the primary winding.
I was working out what I thought might be the internal circuit that makes this light work, so don't be confused by the extra stuff in the drawing.
Just make the two connections across thr primary winding and downstream of the switch.
https://forum.bottlehead.com/index.php?action=dlattach;topic=9518.0;attach=12784;image

[Mucker]

Nice right up Adrian, and drawings. Based on what you have, I would like to add a 120V AC, 4.4ma Red LED to my Moerplay. I use metal tubes and I've been caught a couple times leaving the amp on when I wanted it off. I created a diagram to show what I intend to do if it is correct. Can someone please verify this? It appears to me the easiest place to connect the wires would be to Terminal 33 and 34? Thank you.

Resistor = ? (100 to 1K ?)
Diode = 1N4001
Cap = 0.1uF

P.S. Will there be any noise injected into the pre-amp from this mod? If so, I will skip it. Thanks ...

[Paul Birkeland]

The traditional method is:
https://www.tubesandmore.com/products/dial-lamp-front-panel-indicator-light-relampable
Mount this to the plate.
https://www.tubesandmore.com/products/jewel-fender-style-lamps-bulbs
Pick the jewel you want.
https://www.tubesandmore.com/products/dial-lamp-53-g-3-12-144v-12a-bayonet-base
Put that bulb in.

Wire the bulb to terminals 6 and 7 on the PT-12 in the Moreplay.

For the Crack, use this bulb instead:
https://www.tubesandmore.com/products/dial-lamp-44-t-3-14-63v-25a-bayonet-base
And feed it from pins 4/5 and 9 on the 9 pin socket (or pins 7/8 on the octal socket).

[Larpy]

Here's an option that snaps right into the stock Bottlehead hole:
https://www.mouser.com/ProductDetail/E-Switch/R1973ABLKGRNEF1?qs=4EnmSMTL3HP6Dczx37J6Jg%3D%3D&countrycode=US&currencycode=USD


This switch requires a bit of rewiring, but if I can figure it out, anyone can.

[Paul Birkeland]

Terminal 1A would go to the fused IEC connection that normally goes to the rocker.  Terminal 1 goes to the power transformer like the other wire that leaves the power switch in the stock build.  Terminal 2 goes to "N" on the IEC power entry module.

[TubeGuy12]

Re/Paul B.: thank you for the detailed info on parts and explicit Crack connection points. That's exactly what I was looking for. I now have all the info I need to get it done.

Re/Larpy: The illuminated rocker switch is a fantastically simple idea for those wanting an 'on' indicator without drilling a hole in the top-plate.

Many thanks everyone for the replies. Hopefully others will benefit from this thread long into the future.