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.
The circuit shown is from an old European publication. In it we have the way to activate a relay...
We found this circuit in a European publication from the 1990s. Transistors are still common types...
This circuit was found in an American documentation and can be added to common amplifiers of any...