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BuildCircuit is an online store for selling electronics kits and components related to Arduino, Raspberry Pi, etc. We operate from Sydney, Australia.

We design and sell basic electronic kits and Arduino modules for all electronics enthusiasts.


3 Digit Digital Object Counter DIY kit- UPGRADED

AU $29.50
Calculated at checkout
Current Stock:

This product is shipped from Sydney, Australia. Worldwide shipping available- we ship to USA, Canada, New Zealand, UK, EU and Non-EU countries.

This is one of the best sellers of BuildCircuit.   

This is 3 digits digital object counter do-it-yourself (DIY) kit for electronics beginners and hobbyists. It is the upgraded version of our previous 2 digits and 3 digits object counter.

You can use this 3 digit digital object counter for counting objects or people entering in a room. It can be used by engineers for learning about digital counters. Since it's a DIY kit, it can only be used for learning basic electronics. 

This DIY digital object counter works with VS1838 infrared receiver and photoresistor and there are three seven segment displays displaying numbers from 0 to 999. An IR transmitter is directed towards the VS1838 infrared receiver of the counter module and objects are moved between the two modules. Each time an object passes between the two modules, the seven segment displays show increment in numbers from 0 to 999.

If you are using the laser light, direct it towards the photoresistor and the pointed light should hit the photoresistor so that whenever the light is block, the counter starts counting. 

It comes as a pack of parts kit and is easily assembled if you can follow the silkscreen indicators(labels) and have beginning experience with a soldering iron. You will need to read the resistor bands or use a multimeter to determine the resistor sizes.

The counter module works with 5V. There is a microUSB connector provided. You just need to power up the kit using a 5V mobile charger or any other power adapter. 


  • The distance between the transmitter and receiver modules can be around 10 meters if you are using the photresistor and it is 2 meters if you are using the infrared.
  • The counter module can be reset to 0 at any time and restart the counting.
  • The counter module can be operated with any kind of remote control. Therefore, it can also be used as a remote tester. For each press on the remote control, there is an increment in number. 

What's NEW ? 

  • The output of the kit is highly stable, there is no false triggering at all if you use the photoresistor and laser light for counting. It is 100% accurate.
  • If you use the infrared sensor, the kit will not have false triggering. However, it is affected by sunlight. If you use it inside a room keeping it away from external light sources, it will give 100% accurate result.
  • The previous kits had infrared feature only. Now, it has a photoresistor also.

 Kit package contains components for counter and IR transmitter modules:

A. Components for counter module (30 components)

digital-object-counter-diy-kit-2.jpg  digital-object-counter-diy-kit-3.jpg

  • 1 x PCB
  • 3 x CD4026 Decade counter
  • 3 x 16-pin IC socket.
  • 3 x common cathode seven segment display- (Can be in red, yellow and blue colors)
  • 1 x NE555
  • 1 x 8 pin header for NE555
  • 1 x 10uF electrolytic capacitor
  • 1 x VS1838 Infrared sensor
  • 1 x 3 pin female header for infrared sensor
  • 1 x photoresistor
  • 1 x 0.1uF 50V ceramic Capacitor
  • 1 x 3mm LED- (can be any color)
  • 1 x PC817 optocoupler
  • 1 x 100K - If you use 100K, NE555 outputs pulse for 1.1 sec. See the schematic.  Use 56K if you want a shorter pulse. 56K is not sent to customers.
  • 1 x 10K resistor
  • 3 x 1K resistor
  • 1 x 1N4148
  • 1 x 220 Ohm resistor
  • 2 x Tactile reset switch
  • 1 x MicroUSB power connector
  • 1 x 5 pin female header

B. Components for IR transmitter module (altogether 12 components)


  • 1 x NE555 timer chip
  • 1 x 8-pin IC socket.
  • 1 x Infrared LED
  • 1 x 0.1uF 50V ceramic Capacitor - code 104
  • 1 x 0.001uF 50V ceramic Capacitor - code 102
  • 1 x SPDT Slide Switch
  • 1 x Screw terminal
  • 1 x 330R Resistor 1/4W
  • 1 x 10K Ohm resistor 1/4W
  • 1 x 18K Ohm resistor 1/4W 
  • 1 x 1K Ohm resistor 1/4W
  • 1 x Bare PCB with Silkscreen Indicators
  • 1 x 9V battery connector


Do not look into laser light. It will make you BLIND.


  • 1 x Laser Light module
  • 1 x MicroUSB connector

digital-object-counter-laser-light.jpg digital-object-counter-laser-light-diode.jpg


Documents: The document links given below have not been updated yet. We will soon update it. 

Assembly Video(Updated):


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