Two items found

I finally did find the microphone module from Ebay which might be applicable to a Clapper circuit.  The "red" version is known as a KY-038 and has an electret microphone fed into an LM393 comparator IC but the KY-038 also has a direct mic output.  But I have a "blue" module:

  

It has 3 inputs/outputs instead of 4.  A little searching found this schematic on an Amazon page:

source: https://www.amazon.com/DAOKAI-WE-DA-054-P-Microphone-Sensor-Module/dp/B09YYH736J?th=1  

Nice !  So the blue module feeds the microphone into a transistor amplifier which then drives one half of the LM393 comparator.

There is a level adjustment pot - when there is a loud noise a green LED goes ON.  This is strictly a binary output (on or off) - this microphone is NG for audio, it's meant to detect noise.  As I recall I bought it for use with a Zerobeat kit without knowing this.

One reason why I might have put this blue module away is that the level adjustment is really touchy - seems like either the microphone is deaf or the green LED goes on with any slight noise.  So it might not be useful for a Clapper type circuit.

On a different subject: I also found this binder:

This was with the 2nd Tektronix scope demo module mentioned here:

https://wb9kzy.blogspot.com/2025/07/tek.html 

However years ago I took out the Tek manual (it is a three ring binder) and stuck in some printouts I made of the Carl and Jerry stories:

Not sure what happened to those manual pages :(

Best Regards,
Chuck, WB9KZY
http://wb9kzy.com/ham.htm