Found in an old American publication, this circuit generates signals of various waveforms. The frequency depends on the components. Operational amplifiers are from the period.
This circuit functions as a thermostat triggering a relay when the boil control temperature...
The figure shows how to connect a relay to obtain the latch effect. The circuit is from an...
With this circuit it is possible to use a DC buzzer (not a transducer) as an extension of the...