This sensitive 5-band circuit was found in a September 1995 issue of Electronics Now magazine. The headphones, for greater sensitivity, should be high impedance.
We obtained this circuit from the 1977 National Semiconductor FET Databook. The frequency depends only...
The circuit illustrated in Figure allows external loads (8) to be driven from parallel port...
A high-frequency square wave oscillator using an LC-tuned circuit is shown here. The upper...