The tone generated by this bell changes when we press and release the switch. The circuit is from a 1985 Radio Electronics. Some changes can be made to improve its performance.
We found this circuit in a 1965 magazine. The circuit can be assembled with current equivalent...
This is a typical circuit of a PROM programmer from the 70s. It appeared in the magazine Radio...
If there is an indispensable household appliance in our kitchen these days it is the microwave...