This circuit was found in a 90s Radio Electronics. It produces an ultrasonic signal in a special transducer at the frequency of 2.25 MHz. No information was given about the transformers.
This circuit, suggested by National Semiconductor, provides an output voltage proportional to the...
This powerful alarm circuit was found in the July 1975 issue of Radio Electronics magazine. The...
This two-transistor circuit was found in the January 1994 issue of Electronics Now magazine....