This circuit was found in a 1985 documentation. It provides an audiovisual indication of the presence of moisture or water in the sensor. The circuit can be powered by voltages from 6 to 9 V.
Found in a 90s Hands On Electronics, this small preamp finds applications like microphones and other...
This bridge audio amplifier was found in the July 1984 issue of Radio Electronics magazine. The...
The CUT frequency for this filter is determined by the capacitors. The µA4138 is a quad version of...