The transistors of this circuit found in an English 1980s documentation may be the modern BC548 equivalents. The circuit is battery powered and the earphone must be crystal.
Suggested by Siliconix in 1980s documentation, this circuit uses currently uncommon components. The...
Based on Radio Shack 276-137, this circuit was found in the December 1995 issue of Electronics Now magazine....
Designed to operate with a video camera, this small transmitter was found in the February 1993...