This simple injector circuit can actually be powered by voltages from 3 to 9 V. The frequency is given by C1 which can be between 4.7 and 10 nF. The CMOS can also be 4011.
We found this circuit in documentation from the 1980s. The integrated circuit used is uncommon today,...
This stethoscope or hearing aid amplifier has excellent gain. It was found in Popular Electronics from...
This control for 12 V drills was found in a 90s Elektor. The components are current, and Q1 can be...