The circuit is from an Electronics Hobbyst Handbook from the 90s, being valid for panels of the time, with lower performance. The circuit supplies 2.4V with 125mA current.
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...