Found in a 90’s Electronics Now, this circuit has its output connected to an audio amplifier. The transducer is the type that fits on the finger to monitor the transparency and thus the beats.
This circuit uses an optocoupler with a phototriac or optotriac to drive an external triac. The...
The circuit in figure 1 is a dynamic test for FETs. The characteristic of a FET is displayed in...
This circuit was found in a 1965 Radio Shack documentation. The transistors are from that time....