We’ve been loving the variety of entries to the 2025 One-Hertz Challenge. Many a clock has been entered, to be sure, but also some projects that step well outside simple timekeeping. Case in point, ...

The chances are that many of you will have made an FM “bug” style transmitter, a simple one-transistor oscillator usually driven by a small electret microphone. It’s also relatively straightforward to ...

This low-cost AM transmitter is tunable from 10 to 15 MHz with the help of ½J gang condenser VC1, which determines the carrier frequency of the amplitude modulation transmitter in conjunction with ...

My first battery-powered radio — a ten-transistor Realtone — came from my Aunt Ina when I was about seven. I used to think I was ten, but the songs from 1973 would be wrong: I distinctly remember ...

This FM transmitter circuit uses four radio frequency stages: a VHF oscillator built around transistor BF494 (T1), a preamplifier built around transistor BF200 (T2), a driver built around transistor ...