This power supply uses a Raystor which is a 1964 LDR lamp coupler. The circuit was found in an Electronic Design and the transistor can be replaced with the current equivalent.
The output voltage is adjusted by the trimpot. The power transistor mist be mounted on a heatsink. The 3.9...
Originally, this circuit is from an English magazine, but I found it in Argentina's Radio Chassis...
The previously mentioned versions of monostable multivibrators in this section are not...