Simple Square wave Generator by BC549

Three switchable frequencies: 100Hz, 1KHz, 10KHz
1.5V battery operated, minimum parts counting

This simple circuit generates a good and stable 1V peak-to-peak square wave at 100Hz, 1KHz and 10KHz using a single 1.5V cell as power supply.
An useful feature of this circuit is that frequency changes can be obtained by switching only one capacitor at a time.
Current consumption is about 600µA.

Parts:
[...]
C1_____________12nF 63V Polyester Capacitor
C2______________1n2 63V Polyester Capacitor
C3____________120pF 63V Polystyrene or ceramic Capacitor
C4,C5__________10µF 25V Electrolytic Capacitors
Q1,Q2________BC549C 25V 100mA NPN High-gain Low-noise Transistors
SW1____________SPST Slider Switch
SW2____________1 pole 3 ways Rotary Switch
B1_____________1.5V Battery (AA or AAA cell etc.)

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