This circuit was obtained from a 1980's QST magazine. The circuit can generate 1 to 15 MHz signals with 1 Vpp at 50 ohms load. Used transistors are still common today.
The relay of this circuit closes when the position set in P2 is reached by the sensor...
This circuit is intended to monitor the flame of gas heating systems that must always have a small...
This circuit makes use of an old operational one to generate clock signals that depend on the...