Suggested by Amperex in 1968, this circuit is intended for hearing aids. The integrated circuit used, a TAA370 is not common today.
This circuit, found in an American publication from the 1970s, produces an audible tone in a...
This circuit was found in a 2006 publication. It can serve as the basis for a microcontrolled...
By adding a transistor to the output and some polarization features we can obtain a higher output...