This circuit was found in a 90s EDN. Its purpose is to increase the efficiency of operational amplifiers. Power MOSFETs and inverted zeners support equivalents.
We found this circuit in an 80's Radio Electronics. The circuit uses a PTC sensor and an LED...
In this circuit a 12 V lamp or LED blinks with the music signal applied to the input. R depends on...
Using a period sensor, this circuit was found in the February 1986 issue of Radio Electronics...