Introduction: Infrared and Laser Operated Digital Objects Counter

This is a basic digital object counter for electronics beginners. Previously, I was selling this as a do-it-yourself kit. Now, it is sold as a fully assembled kit because several customers complained that it takes a lot of time to build and some customers could not make it.

If school teachers want to buy a do-it-yourself(DIY) version of the kit, they can contact me.

The kit is based on the CD4026 decade counter. The counter module counts from 000 to 999 and it only counts up.

The infrared transmitter module is directed towards the infrared sensor (on the counter module) and when the infrared ray falling on the sensor is obstructed, the counter module gets triggered and increases the count. In the same way, the laser light module is directed towards the photoresistor on the counter module and when the light is obstructed, the counter increases the count.

The infrared sensor is sensitive to tube light, CFL light, and sunlight and any other sources light that generates infrared. However, if the device is placed anywhere avoiding any unwanted infrared interference, it gives 100% accurate results.

There is no false triggering or false counting. It always counts accurately provided that there is no infrared interference.

The kit has been designed to allow the users to use either infrared or photoresistor. There is the possibility of using both sensors at the same time also. The 3 pin female header allows the users to remove the infrared sensor if the user wants to use photoresistor only.

The counter module comes with a micro USB connector module so that the users can power it up with a 5V DC adapter, for example, using a mobile phone charger or by connecting it to a computer.

The laser module also has a micro USB connector module which also works with DC 5V.

The infrared transmitter module has to be powered with a 9V battery.

How does the digital object counter work ?

The counter module has a NE555 timer-based monostable circuit that gets triggered whenever the infrared light (falling on the infrared sensor) or the laser light (falling on the photoresistor) is interrupted. The output pin 3 of the NE555 is connected to one of the CD4026 chips (via PC817 optocoupler) and the other two CD4026 chips are further connected together. Whenever the timer gets triggered, it sends a pulse to the CD4026 decade counter, which in response to the trigger, starts counting. The NE555 timer on the infrared transmitter module is configured in astable mode giving 38Khz infrared signal to the sensor.

The kit is available at BuildCircuit Store


The kit package includes:

1. A fully assembled and tested counter module with 3 seven segment displays.

2. A fully assembled and tested infrared transmitter module

3. A laser light module

The kit is available at BuildCircuit Store

Other accessories that users have to arrange:

1. 2 x 5V DC adapter or a mobile phone charger to power up the kit and the laser light module

2. 2 x micro USB cable

3. 1 x 9V battery to power up the infrared transmitter

Step 1: Test the Counter Module

First of all, power up the counter module with a 5V DC power adapter. You can use your mobile phone charger also. All the seven-segment displays should display either 000 or 110. Then, press the 'count' switch to test if the counter counts. It should count up. Then, press the 'reset' switch to check if the number resets to 000.

Use a normal torch, illuminate the photoresistor and see if the LED turns on and the counter counts. Similarly, use a normal TV remote and press the power button of the remote and see if the counter responds or increases the count on every press on the remote.

Step 2: Test the Infrared Transmitter Module

After testing the photoresistor and infrared sensor of the counter module, test the infrared transmitter module by powering it up with a 9V battery. As soon as you connect the battery, it will turn on the red LED. Point the transparent infrared LED towards the infrared sensor on the counter module and obstruct the ray falling on the sensor. It should increase the count on the counter module.

The infrared transmitter module generates infrared rays at 38Khz.

Step 3: Test the Counter With Laser Module

Power up the laser module with a 5V DC adapter. Point the laser light on to the photoresistor. As soon as the laser light illuminates the photoresistor, the NE555 gets into the monostable mode and turns on the 3mm LED present on the counter module. Make sure that the laser light remains fixed and continuously illuminates the photoresistor. Move your hand or any object to obstruct the light, the counter will increase the count.

The kit is available at BuildCircuit store