Things which you can learn:
*Application of the NE555 timer IC in the monostable mode of operation.
*Application of the melody generator IC UM66.
*Use of a condenser mic as a sound sensor.
*Application of NPN transistors for switching and amplification purposes.
*Application of triacs.
Product Description
Build an awesome automatic porch light with melody, and park your car tension free into the garage. The concept is that when you bring your car near the garage, just beep a horn and the porch light will automatically light for the predetermined time with a sweet melody accompanying it.
Working:
The heart of the Automatic Porch Light with Melody circuit is the NE555 timer IC which is triggered by the sound signals converted into electrical signals. Normally, trigger pin (Pin2) of the NE555 remains high. However, when this pin goes low, the NE555 get triggered to run as a monostable. This causes the output pin (Pin3) to go high for a specific time duration. This time period can be controlled by rotating the potentiometer VR1 (which forms a part of the timing circuit) to get different resistance values.
The condenser microphone picks up the sound signals from the horn of the vehicle and converts these to electrical signals, these are then amplified by the NPN transistor BC549 (T1). During the negative transition of the signal at the collector of transistor T1, the NE555 is triggered as a monostable and its output goes high to activate the melody generator IC UM66. The electrical signals generated by UM66 at its output pin (Pin1) is amplified by two NPN transistors BC547 (denoted as T2 and T3). These amplified signals are then fed to the loudspeaker which generates a musical tune for the set time duration.
Summary
The Automatic Porch Light with Melody automatically switches ON the porch light for a specific time duration to allow a person to park their vehicle in the garage . The circuit also generates a melodious sound for the time duration when the vehicle is being parked. Build the kit and give yourself an upgraded technique to park the car No. of ICs used: 2