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Subject:
light detector
From:
Butch Bussen <[log in to unmask]>
Reply To:
For blind ham radio operators <[log in to unmask]>
Date:
Sun, 12 Apr 2015 17:21:26 -0700
Content-Type:
TEXT/PLAIN
Parts/Attachments:
TEXT/PLAIN (15 lines) 
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.

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