This circuit is my first ‘small-time’ electronics project. It’s basic function is to switch a certain circuit ‘on’ if it is whether exposed to light or to darkness.
As you can see, the concept of this project is basically transistor biasing. I recommend this circuit as a ‘simple’ project in Electronics I or to people who wants to learn the basic concept of Electronics.
Let’s do some hands-on
The circuit I created is light-activated(I apologize for some irrelevant wires connected in the breadboard). There are various real-life application of this project. It can switch devices either DC or AC appliances (220 volts). I have here a simple video how it works.
The LED acts as the component/appliance being switch. I cover the LDR to show you how the light affects the switch. You can see that when the shadow of my hand covers the LDR, the LED is off. While if it is exposed to light, it is on. You can also notice that there are noises that affects the circuit that’s why it seems that it doesn’t work properly. The function of the POT is to adjust the color intensity to switch the device. I used a cellphone camera that’s why the quality of the video is not that good.
Now, the dark-activated switch is your homework.
Rowatronix 