The circuit shown consists of a power stage for relay excitation. 2N3053 can be a BD135 and 2N406 can be replaced with a BD136. R3 depends on the trigger voltage.
This circuit, which presents a certain danger and should be used with caution, was found in the...
Found in American documentation from the 1970s, this circuit is intended for amplifying analog TV...
This dimmer configuration is quite old, as it was found in a 1967 publication. The triac can be of...