This circuit is from Dutch documentation from 1967. The circuit works with a component of the time, the BRY39, which is uncommon today.
This power supply is protected from shorts in the load. The BD135 must be mounted on a heatsink...
Found in a 1966 publication, this circuit is a simple version of a field strength meter. The diode...
The basic idea of this 1989 circuit is to trigger a relay for a while when a call signal occurs on...