We found this circuit in the 1964 RCA transistors manual. The sensor may be a common LDR and the transistor BC558. The relay has an operating voltage according to the power supply.
This circuit causes an instrument needle to oscillate to signal an event. The circuit is powered by...
This bridge circuit for the bench can have several uses. We found it in Radio Electronics magazine...
July 2017 - The new Diodes Incorporated AP7350 LDOs with ultra low quiescent current can be...