This circuit was found in a 1969 Mullard publication. The transistor may be the modern equivalent of BC548. Observe the relatively high supply voltage.
This low-current control circuit has a lamp as a load, but can have other types of devices, such...
The varactor or varicap diode tunes the signal for listening to SSB signals on a common receiver. The...
This power supply is not protected from shorts in the output. Output voltage is given by the...