This circuit is from a 60's documentation. The capacitance C1 can be between 20 pF and 0.01 uF depending on the generated frequency. Equivalent transistors may be employed.
Frequencies up to 50 MHz can be produced by this circuit, depending only on the used XTAL. L and...
Unlike the previous detector circuit, this includes the inverter not requiring a high voltage...
This circuit triggers a relay when the set temperature is reached. The circuit is from an old...