Found in documentation from the 1990s, it uses a sound effects integrated circuit, the SN7677 from Texas Instruments. Unusual component these days.
This small 3 transistor transmitter was found in an English publication from 1963. The coils must...
We find this circuit in a 1977 technical documentation. The circuit generates signals in a wide...
Found in a 90s Radio Electronics, this circuit is intended to trigger a relay when the current in...