This circuit can keep a set of lamps on for up to 1 minute, time given by C2 and R2 that can be changed. The load depends on the relay. The circuit is old, from 1988 documentation, but totally viable today.
We found this circuit in an Electronic Design from the 80's. The generated tone can be changed as well...
In the figure we have an oscillator circuit by Wien Bridge (Wien Bridge Oscillator). The frequency of...
We found this circuit in Intersil documentation from the 1980s. The circuit applies to other...