This circuit is suggested by General Electric in 1966 documentation. The Triac must match the engine. The resistors depend on the triac's sensitivity to firing.
This signal injector and tracer (follower) was found in an old American documentation. The...
This circuit for PC and which can also be used with microcontrollers was found in an English...
This fuzz uses only one transistor that can be the BC548. Signal input and output cables must be...