This 3-channel transmitter for amateur analog TV from 902 to 908 MHz was found in a QST magazine from the 90s. The circuit is critical and must be designed with special care in the layout of the board.
This circuit locks when the sensors are opened. The relay can be 6 or 12 V depending on the power...
The indicator instrument of this transistor tester, from an Argentine publication of the 1970s,...
Found in American documentation from the 90s, this circuit uses TTL technology and is therefore...