This circuit was originally recommended to give the call signal on intercoms. However, it can be used with other applications. The circuit is from 1978 documentation. The transistor may be the BC548.
This analog voltmeter with great sensitivity and input resistance has a traditional configuration found in...
This circuit is used to turn on the headlights when it gets dark. The circuit is from an...
The indicated circuit is based on the National Semiconductor LM3524 which is not an easy component to...