This OF-1 LO oscillator was found in a 1980s American documentation. The transistor can be any general-purpose and C1 / C2 are determined by the frequency.
We found this circuit in an 80's Radio Electronics. The circuit uses a PTC sensor and an LED...
In this circuit a 12 V lamp or LED blinks with the music signal applied to the input. R depends on...
Using a period sensor, this circuit was found in the February 1986 issue of Radio Electronics...