This circuit was obtained from Radio Electronics magazine, October 1987. The circuit uses a triac to control the heating element current. The transistors are general purpose.
This circuit using only transistors was obtained from Ferranti's 1969 documentation. It can be...
This sensitive circuit can be designed with FETs such as BF245 and MPF102. The sensor is a silicon...
Found in Popular Electronics from the 90s, this circuit generates two tones that are selected by a...