Butch, will you send me a copy of your circuit? It sounds very similar to a
light probe circuit that Dr. Crnmer, Wayne Thompson, and I worked on several
years ago. 

Ron, K8HSY



-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]]
On Behalf Of Butch Bussen
Sent: Sunday, April 12, 2015 7:21 PM
To: [log in to unmask]
Subject: light detector

I thought I kept the message I wanted to respond to, but I didn't. 
Anyhow, I wrote an article in qst way back in July of 1985 called the
squawker.  It uses a 555 chip a couple resisters and a photo cell and almost
anything for a speaker.  We actually used an old cassette recorder
mlicrophone for the housing and the cartridge as the speaker.  I can put up
the circuit if anyone wants it.  Will run on 5 volts, not sure how high the
555 will go, but I ran mine on a 9v battery.  If you put in a closed circuit
phone jack as I did, it can become a continuity tester.
Pitch changes with brightness.
73
Butch
WA0VJR
Node 3148
Wallace, ks.