Featured in the February 1949 Radio Electronics magazine, this benchtop instrument generates multi-range audio signals. The circuit has 6 tubes including the rectifier.
Another way to increase the sensitivity of the circuit with the amplification of the sensor...
We found this circuit in the Radio Electronics magazine of January 1986. The frequency is given by the...
This circuit was found in the September 1984 issue of Radio Electronics magazine. The circuit is...