The voltages in an adjusted range in the trimpots are indicated by 3 LEDs. The LEDs indicate when the voltage is below the range, above the range and in the range.
This 555 IC circuit was found in June 1984 Radio Electronics magazine. This circuit detects a...
We found this circuit in a 1976 publication for radio amateurs. It was originally intended for use in...
The integrated circuit used in this small transmitter is not very common today. The coil has its...