David A. Johnson
David A. Johnson
Areas of interest of the author: Audio Oscillators Measurement Light Supply Solar Beginners Digital Bad Prescriptions
Publications on RadioLocman by the author David A. Johnson:
- 3V sweeping siren alarmA while back I was challenged by a visitor to the website. He needed a very loud sweeping...Mar 17, 2026
- Single IC forms sensitive modulated light receiverThe circuit uses a very inexpensive C-MOS IC that is connected to a small photodiode. Using a...Mar 6, 2026
- Charge coupled MOSFET relayThis circuit acts as an AC/DC relay with a rating up to 50 volts peak and up...Jan 22, 2026
- Solar mason jar lightI have modified several commercial solar garden lights over the years. I switch out the LED, solar...Dec 10, 2025
- CMOS Schmitt trigger IC makes VCOBy changing the supply voltage fed to a classic 4584 Schmitt trigger type oscillator, the...Nov 24, 2025
- On/off latch circuitOften you want to turn on and off power to a device with a single pushbutton switch. The circuit...Oct 14, 2025
- Circuit forms ideal diode functionThis circuit uses a low power op Amp and a p-channel FET to form a diode function with a very low...Oct 14, 2025
- Circuit forms divide by 1.5 counterTwo inexpensive ICs divide a TTL clock signal by 1.5. By following the circuit with...Oct 10, 2025
- Micropower CMOS oscillator, draws only 0.5 µAConventional astable oscillator circuits that use CMOS logic gates, bipolar transistors or low...Aug 31, 2025
- +5V powered charge pump battery chargerThe circuit below will trickle charge a four cell pack of AA or AAA NiMH batteries. The circuit...Jun 30, 2025
- 1 amp current injector circuitI designed and built this thing many years ago. I published the hobby circuit in the now...Jun 26, 2025