We found this circuit in a publication by General Electric in the 1980s. The transistors and the PUT are from that time. The control is done by a tachometer based on an optical coupler.
This circuit for analog video signals was found in a Linear Technology integrated circuit manual. The...
This tuned circuit was found in a 1966 Electronic Circuit Handbook. The transistor can be any...
This Siliconix circuit was found in a 1980s documentation. The coil consists of 18 turns of 22...