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.
This General Electric circuit is from the 80's. The PUTs used in this meter are not common...
Found in a 1964 Electronic Design, this circuit generates pulses based on an avalanche diode of...
This circuit, which consists of an audio oscillator, was found in a Radio Electronics magazine from...