An electronic bird song generator circuit

This is an electronic bird chirp generator circuit designed to produce bird chirping-like sounds.

The transformer is a small audio transformer, model LT700. The primary is center tapped and has an impedance of 1Kohms at 1KHz. The impedance of the secondary is 8 ohms. This circuit is powered by a 9V power supply.

How electronic bird chirps work

The inclusion of R1 and C1 gives this oscillator its characteristic "chirp". When the 100u capacitor charges through the 4.7K resistor, the bias of the R1 transistor is cut off. This causes the oscillation to stop, the capacitor discharges through the base-emitter circuit of the transistor, and the oscillation starts again. Changing these components changes the frequency of the chirp. Chirp is also related to voltage. When the push button switch is operated, the 100u capacitor is charged. When it is released, the oscillations decay and the chirps become faster.

Component list:

Resistor

1 x 47k Ohms

1 x 4.7k Ohms

transistor

1 x BC109 or BC337

transformer

1 x 1K:8Ohm audio transformer

capacitor

1 x 22nF ceramic

1 x 10nF ceramic

2 x 100uF electrolytic

other

1 x 9v battery and clip

1 x plastic board

1.5m copper foil tape

1 x C2222 8Ohm speaker

1 x Momentary Push Switch