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 was found in an old documentation and can be implemented with BC549 transistors. The...
This mid-waveband receiver was found in a book on transistors from 1954. The antenna coil is of...
Old multimeters used a 22.5 V battery for high resistance measurements. If you have one, you...