This signal amplifier for ATV in the 427 to 439 MHz band was found in a magazine 73 for radio amateurs of the 90's. The circuit is installed next to the antenna on the mast itself.
This aperiodic circuit was found in an old English documentation. The transistor can be any JFET...
The values of R1, R2, R3 and C1 depend on the signal to be integrated. The circuit is from Radio...
This circuit triggers an LM380 oscillator, producing an audio tone with light falling on the LDR....