This circuit was found in 1960s Radio Electronics. The circuit uses components from that time. The triac is according to the controlled load. The sensor is a common LDR.
This few-watt amplifier was found in the August 1975 issue of Radio Electronics magazine. The...
This mini siren, found in a 2003 publication, powers a small piezoelectric transducer, but a...
This circuit is from a documentation from the 70s, but it can be assembled with a TIP32 transistor in an...