This circuit was found in a General Electric documentation from 1965. The circuit is full wave for 600 W power with the indicated triac.
This is the circuit of a commercial amplifier sold in Japan in the 1960s. The circuit for hearing aid...
The integrated circuit used in this 80's application is very hard to find today. The circuit is of an...
This circuit is from March 1978 Radio Electronics. The 4-digit circuit uses a period module and is...