This 4-tube circuit was found on a Radio Craft from December 1945. The circuit has excellent sensitivity. Power comes from a power supply with a transformer.
This circuit has a normally low output that is triggered by a high pulse. The circuit is from...
The figure shows the equivalent circuit for the LM381 audio preamplifier IC. The circuit was found...
This variable high pass filter covers the range from 23 Hz to 700 Hz with the components used. The...