This siren configuration found in a documentation from the 1980s can also be seen in many of our projects and in this circuit bank. Transistors are common, but Q2 can be of power for a higher voltage supply.
This small experimental transmitter with the CK722 transistors was found in Radio Electronics...
We found this circuit in the old Mullard transistor reference manual from 1960. The circuit is...
This circuit is designed to be used with the infrared transmitter two circuits before this one....