This is the receiver for the previous transmitter. The signal consists of digital pulses with a compatible TTL or CMOS output. The integrated circuit is a 4093 and a photodiode of any type.
This well-known siren configuration using complementary transistors is from a 1980s documentation. The...
This circuit was found in an old American magazine and could make use of more modern components...
This circuit is from the Philips integrated circuits manual of 1990. It is intended for magnetic...