This is a simple up and down circuit that can be implemented in various digital circuit applications. I know this is useful to students in their projects and thesis design.
I use a 74ls190 (SYNCHRONOUS UP/DOWN COUNTERS WITH DOWN/UP MODE CONTROL) for this circuit. You can check it’s datasheet to know its capabilities.
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.
Traffic-Light is a common project given to engineering students. In this purpose, I include this project in my list. After getting the schematic (I forgot where I get this), I started to make one. I modified the circuit because it doesn’t work correctly. The diode in the pin10 of 4017 counter must be connected to the red LED. Here is the circuit(unmodified).
It uses a 555 timer IC and a 4017 counter IC. In addition, by adjusting the 1M preset, the sequence can be varied from 7 seconds to 2.5 minutes.
I formed it in a breadboard to show you how it works.
Here is a video:
Reminder:
Please understand that this is just a simple traffic light circuit. You can design a different kind of traffic light like traffic light for both intersection, traffic light for railway, etc. This is just a ‘small-time project’.
You can also check an improved version(two way traffic light) of this circuit on this blog.
Components List:
Rowatronix 