This low-power experimental oscillator can generate audible signals in the range of 100 Hz to 1.2 kHz, driving a small piezoelectric transducer or a crystal earphone. The project can be powered from four AA cells (6 V), a 9 V battery, or a 12 V power supply or battery.
The circuit drains only a few milliamperes, which can extend the batteries life to many days if they are used to power the circuit.
Potentiometer R1 adjusts the frequency and can be altered in a large range of values. Potentiometers up to 1 M ohm) can be used, changing the frequency range lower limit to about 10 Hz.
C1 can also be altered, and values between 0.01 µF and 0.1 µF are suitable. Large Cl values will give lower frequencies. This circuit can be used as a part for alarms, games, toys, and to learn a great deal about the 4093.
The output waveform is square, and frequencies between 1,500 and 3,000 Hz will provide more audio power with the recommended Radio Shack transducer.
IC1 - 4093 CMOS integrated circuit
BZ - Piezoelectric transducer, Radio Shack 273-073 or equivalent (a crystal earphone also can be used)
R1 - 100,000 ohm potentiometer
R2 - 10,000 ohm, 1/4 W, 5% resistor
C1 - 0.022 or 0.033 µF ceramic or metal film capacitor
C2 - 100 µF, 16 WVDC (working voltage, dc) electrolytic capacitor
