It is always good to break a big project into small modules and test them separately. After you confirm that the small modules work properly, you can combine them together and make it a big project. In this article, we will see how we can combine small projects(dark sensors) to make a bigger project.
We will combine two independent dark sensors(Small Projects) to make a simple clap switch(Big Project).
This project is based on previous clap switch circuit. Please click on the link to see how the circuit works. The previous project was built using BC547, whereas, this is built using 2N3904 and NE555.
Step 1: Make a dark sensor.
Step 2: Make a dark sensor using NE555 timer.
Here, 555 is configured in monostable mode.
As you block light falling on LDR, the LED D1 glows for a time duration defined by the combination of resistor R4(4.7K) and capacitor C2(100uF).
Please try with different values of R4 and C2 to see changes in the timing of the circuit.
Step 3: Combine two dark sensors to make a clap switch
– Replace LDR (from the transistorized circuit) with an electret microphone and 10K resistor. HOW TO USE ELECTRET MICROPHONE?
– Remove LED D1 from the transistorized dark sensor.
– Then connect one terminal of 100nF capacitor to the collector of transistor Q2 and the other to Pin 2 of transistor 555 timer.
– Remove LDR and resistor R2 (10K) from 555 timer.
– Change timing of the 555 timer, if you want. HOW TO CHANGE TIMING?
The final schematic looks like this:
Here, I have replaced 4.7K with 47K, to get longer time period.
Working of this project:
You know that the 555 timer has been configured in monostable mode. If you put your finger on Pin 2, the timer will be triggered, and the LED will be switched on. In this project, the triggering is done by the transistorized circuit. When you blow air or clap near the microphone, the transistorized circuit triggers the 555 timer and makes it switch on the LED(connected to Pin 3). The triggering signal goes via 100nF capacitor that is connected between collector of transistor and pin 2 of 555 timer.
This project can be made using BC547 transistor also. CLICK HERE.
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