This converter or inverter uses components that are still common. The transformer is the type found in old tube equipment. The power transistors must be mounted on heat radiators.
This circuit is from a 1980s Motorola documentation. The circuit can be made with modern...
This well-known circuit triggers a relay when light striking the phototransistor is cut off. The...
This circuit generates a pulsed tone whose frequency depends on C2 and whose flashing depends on...