This commercial transistor tester circuit (EICO 666) is from a Japanese publication from the 1960s. The switch selects the types of test with the switching of the terminals and the gain ranges.
This simple circuit allows the monitoring of both audio and RF signals. With the switch in one...
This circuit was found in documentation from the 1980s. The integrated circuit used is uncommon today...
With a light pulse on the Q1 sensor the circuit turns on and locks. To switch off, a light pulse...