GHR Audio

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The Bell System Technical Journal 1951-01: Vol 30 Iss 1

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Bell Laboratories Record 1937 June

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Bell Lab Record 1934 December

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The Bell System Technical Journal July 1934

Script wrote: Thu Sep 11, 2025 11:02 am R22 1/4 W, got it. Thank you.

1/2 W

Don't use super bright LEDs on the sidechain! Use LEDs with luminous intensity of 300 mcd or less. I used 80 mcd LEDs.

D1 = 4007x

+/- 18V will work too and 166 mA should be enough or go with DCWN06A-15.

1/4W should be fine on the sidechain, except use 1/2W on R22.

I didn't have the zener yet when I took the picture and I added it later. It will work without the zener, but it's better if it is there.