This circuit was obtained from American documentation from the 1990s. The transformer can be a car ignition coil that works like an autotransformer. Q2 must be equipped with a heat sink.
This simple charger was found in a 1980s documentation. The transistor may be the TIP42 with a...
This circuit is used to run light bulbs around street signs. Incandescent lamps up to 40 W are...
This high frequency or RF amplifier was found in a 90s Popular Electronics. The circuit can be...