This circuit can be used to test crystals from 1 to 20 MHz and also has an output to measure their frequency. We found it in the November 1998 Electronics Now magazine.
This filter can be used to eliminate hum in sound equipment. Operational amplifiers can be 741 and...
This signal amplifier for ATV in the 427 to 439 MHz band was found in a magazine 73 for radio...
This simple three-LED sensor uses an NTC at the input. The circuit is based on an uncommon...