This circuit triggers an alarm in the event of a power failure. The circuit is from an 80's documentation, being powered by 9 V battery. The parts are common today.
This circuit was found in an EDN from the 90s. For the components indicated, the frequency is 10 kHz....
This circuit provides voltages and a 1 kHz signal for measurement bridges. The circuit is from...
We found this circuit in an old documentation, but it is still current. General purpose...