We found this circuit in a 1987 documentation. It is a multi-tester with neon lamp and LEDs operating with both low continuous voltage and high alternating voltage.
We found this circuit in an English documentation from 1979. It shows how you use a 100 uA...
This circuit for high-impedance magnetic headphones was suggested as an experimental amplifier for hearing...
This circuit was found in a 1987 publication. A 4017 sequentially counts time in steps set by...