This circuit is from Motorola's Linear Databook from 1990. The integrated circuit and transistors are uncommon, but the circuit can be assembled with equivalents.
This counterphase circuit is from a 1973 publication, and can work with mains voltages or 12 V....
This circuit for the 60 kHz range was found in 73 magazine and published in 1995. The circuit uses...
We found this automotive alarm circuit in a 90's Popular Electronics circuit. The circuit emits a...