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.
The circuit shown, found in a 2004 documentation, allows the use of a telephone, without the...
This simple circuit needs a high gain stage to compensate for losses. It consists of a passive tone...
The time constant for this circuit found in a 1973 publication is given by R and C. The shot is...