DTMF Decoder (CB25048E)

This circuit was found in the 1987 Radio Electronics magazine. The components used are integrated circuits of the time.

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Simple Alarm with SCR (CB24114E)
Found elsewhere in this section, this circuit is from the April 1971 Radio Electronics magazine. Note...
Relay Drive AC Stage (CB12182E)
With this circuit, a relay can be activated from an alternating signal with frequency up to a few...
Theremin Optical (CB14988E)
The sound of this experimental musical instrument is produced by the movement of the hand in front...