This 5.1 MHz circuit was found in a 1980s documentation. The frequency is given by the crystal and general purpose transistors can be used.
This circuit allows the use of a milliammeter in the measurement of low frequency alternating...
This amplifier was found in an old publication of 1990. With the changes, it may still be...
The circuit shown here produces a pure square tone of 440 Hz that is suitable for musical...