This circuit was found in a 1975 documentation. The SCR can be of any type and in this case, we have the horn activation. The relay must be a 12 V type with high contact current.
This configuration, found in many publications, is from an American book from 1981. The power...
The circuit shown is from an American publication from 1970. It produces a tone that attracts fish...
Found a documentation on PCs from 1996, this circuit can be used as a shield. The relay is rated at...