This commercial circuit is from a Japanese magazine from 1967. It uses germanium transistors, and the coil can be made with 80 to 100 turns of fine enameled wire on a ferrite rod.
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....