Using the CMOS IC 4046 we found this VCO in the November 1984 Radio Electronics magazine. The center frequency is given by the capacitor. The maximum frequency is around a few megahertz.
This circuit produces an intermittent ring tone being triggered directly by the telephone line. However,...
The power of this small amplifier reaches 75 mW per channel depending on the voltage and the load...
This circuit activates a fan when the temperature exceeds a certain value, sensed by diode Q1. The...