Electronic Birthday Candle

The LED turns ON when you speak into the microphone or blow into the microphone. 

Figure 1: Device.

This is a simple microphone DC current amplifier circuit. Because the circuit does not amplify the voltage (amplifies current) you will have to hold the microphone near your mouth for the LED to turn ON.

You can see my circuit working in this video:

Step 1: Design the Circuit

I have drawn the circuit on East Eda software:

Figure 2: Circuit.

The three transistors amplify the microphone current. If you are using two 1.5 V batteries you will need to change the Rled resistor from 1 kohms to 100 ohms.

Step 2: Make the Circuit

I made the circuit on a matrix board by twisting the wires and pins together. Thus I did not use the soldering iron.

Figure 3: Make the circuit.

Step 3: Testing

I tested the circuit at night:

Conclusion

Now that you made this circuit you might want to try connecting the microphone directly to the transistor. There could be an issue with the transistor not turning ON if the microphone resistance is very small.