This two-transistor circuit consists of a powerful industrial-use siren. The circuit is from a Radio Electronics from November 1963. The powerful power supply is included.
This encoded lock circuit with alarm for use in homes was found in a publication from the 90s. The...
The circuit shown was found in the 1994 National Semiconductor Linear Applications Handbook. The...
This circuit is from a 1979 documentation. The FET can be the BF245 or MPF102 and the bipolar...