This circuit was published in a 90s Radio Electronics. The circuit uses the well-known LM386 that appears in a large number of projects on this site.
This 1987 signal injector included the power supply from the power grid. The transformer is 6 + 6...
This amplifier was found in a 70s documentation. The product gain x bandwidth is 350 MHz. The...
This simple receiver with junction FET uses a high impedance magnetic earphone (over 2 k). Power...