PRODUCT DESCRIPTION:

This is a very interesting circuit. All of you have seen and used candls in birthday parties.What do you do with a candle in end.....?You just blow it Off.These kit uses the same theme:Make an Electronic candle which can be blown off with a whiff of air.

Operation:

The circuit is built around the popular NE555 timer IC operating as a Bi-stable Multivibrator. Whenever the trigger pin is pulled Low, the output goes high and remains high for indefinitely, till the end threshold pin is pulled High. When a whiff of air is blown over the condenser microphone , its capacitances changes , this result in a small pulse voltage at the junction of the potential divider formed by the 10K Resistors and the mic. This small pulse passes through the 0.1uF capacitors and reaches the base of Transistors (bc545).Since the base is already biased with the 2.2M and 100k resistors; even a small pulse at the base will make the collector drop to Ground voltage(acting as a switch) . The collector is connected to  the Trigger pin of NE555 timer IC. Hence , whenever a pulse is received by the mic , Output of the 555 timer goes high ( Switching OFF the LED). The button is connected across +ve voltage and thresold pin(pin no. 6).

Thus the overall operation is:

1. Switch ON the candle by pressing the push button switch.

2. Wait till the candle(LED) glows to full brightness.

3. Blow mild air over the condenser Mic to switch OFF the candle.

PACKAGE INCLUDE:

• 1 X 1K Resistor

• 3 X 10K Resistor

• 1 X 100K Resistor

• 1 X 2.2M Resistor

• 1 X 5mm White Led

• 1 X NE555 IC

• 1 X 100nF Capacitor(104)

• 1 X BC548 Transistor

• 1 X Condenser Microphone

• 1 X 4 pin Tactile switch

• 1 X 9V Battery Snapper 

• 1 X PCB and Datasheet