This circuit was found in Delco documentation from 1965. The transistor is of the time, but any current power PNP with at least 500 mA collector current and 100 V collector voltage can be used.
Of course, other frequencies can be generated by changing the components. The circuit generates a...
This circuit was found in a 1974 publication. It provides a tone indication of the temperature sensed by...
This spy transmitter can be plugged directly into a power outlet. The power comes from a regulated...