Chess game timer (CB7084E)

This RCA circuit provides timing intervals from 5 to 120 seconds. The components are of the time, but they admit modern equivalents.

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Optoelectronic detector (CB15608E)
In this circuit the signal from the phototransistor is amplified by a Darlington stage and then...
Drill Speed Control (CB1353E)
This simple half-wave control using an SCR, which may be TIC106, has been obtained from a US...
Car alarm (CB23933E)
We found this circuit in Radio Electronics from October 1968. The circuit drives headlight bulbs...