Introduction: MonoPong

About: I like to play with electronics and other fun stuff, modify things to make them more useful or just more funny, putting things together that seem not to fit to make funny stuff. Sharing ideas make the world a …
When I saw this amazing 1D-Pong-Game at Hack-A-Day, I thought "What a great idea - I want to make one". In fact it is a good projects for using microcontrollers, but I also think it is a great project for using logic ICs. I am fascinated by the simplicity of these ICs, and I was wondering if I could make a 1D-Pong-Game without a µController.

Here it is: MonoPong involves a CMOS NAND Gate (4011), a 4510 up/down decade counter, 4028 BCD to decimal decoder chip and as an oscillator an NE555 in astable mode.

The Game
is a 1D-version of the famous PONG game. The "ball" moves from left to right. The player has to push the button at the right moment to strike it back. If he misses the "ball" the other player wins one point.

Step 1: How It Works

Instructables is not only about how to make something, but also about learning how something works. So, let me first explain how the circuit works.

IC2 in the schematic is a CMOS 4510 up/down counter. Driven by IC1 which is a NE555 in astable mode it counts from 0 to 9 in BCD code. Normally it counts from 0 to 9, but it can be switched to count in the opposite direction by b setting pin 10 to HIGH.The BCD code is converted into a decimal code by the CMOS 4028 (IC2). This one drives the display and gives out the counted number in form of one of 10 LEDs lighting up.

The last IC is a 4011 NAND gate. Two of the NAND gates are connected to work as a RS flip flop. The inputs of the other two NAND gates are connected to the buttons and LED1 or LED10. The outputs are connected to the RS flip flop. If you push the button at the right moment, which means for example when LED10 lights up, the output of the NAND gate sends a LOW signal to the flip flop which changes its output state (eg. from HIGH to LOW or vice versa). This signal goes to pin 10 of the 4510 to change the direction of the count. The "ball" bounces back.

Step 2: Parts, Tools, Skills

For building the monoPong game you need the following ....


  • 10 LEDs: 8 red, 2 blue -- or choose the colors you like
  • 2 momentary push buttons
  • 1 on-off switch
  • NE555
  • CMOS 4510
  • CMOS 4028
  • CMOS 4011
  • Potentiometer 100k
  • Resistors: 1x 5k, 2x 100k, 1x 470 Ohm
  • Capacitors: 1x 47µF, 1x 4.7µF, 1x 100nF
  • Wire (a lot, different colors)
  • Small wooden box, or another enclosure
  • Perfboard
  • Double sided tape
  • 9V battery and clip


  • Drill
  • Soldering iron and solder
  • Helping Hand (make your own)
  • Wire cutter
  • a set of small pliers
  • Scissors
  • Multimeter

Step 3: The Enclosure

We start with the easiest part: Drill the holes for the LEDs, pushbuttons, potentiometer and on-off-switch to the box. You can already mount these parts. I removed the metal parts of the box to have a cleaner design.

Step 4: Soldering the Circuit

Soldering the circuit it the hardest part of the work in that project. I spent a whole day (with lunchbreak!) for it. There are not much components, but a lot of wire.

Do not solder the ICs directly to the board - always use sockets!

Begin with the NE555 circuit and solder all connections step by step. Dont forget to double check all your connections by using your multimeter to avoid mistakes. It could be difficult to find the missing/wrong connection later. Refer to the circuit diagram and work very accurate. (click here for a big version of the diagram)

I did some modifications in my last version: I left out the reset button (S1) and the related pull down resisor, because it is not necessary for the game. I just connected the reset pin ( 9) to GND. I also substituted the ten current limiting resistors (next to the LEDs) with only one. One is enough because only one LED lights up a time.

In the last step solder the wire for the LEDs, poteniometer, on-off switch, battery clip and the two pushbuttons. I used different colors to not get confused when wiring these parts up. I highly recomment you to do so.

Now its time for the ICs to join the party. Put them to the sockets. Put the board into the box and wire the LEDs pushbuttons, potentiometer, battery clip and on-off switch. Again: carefully double check every single wire! It is easy to make mistakes here.

Step 5: Finishing

Glue the circuit board to the box. I also had to glue the potentiometer because the wood was too thick to screw it. I closed the box and fixed the top cover with double sided tape.

Add a 9V battery to the clip and start playing with your friends!


I wanted to keep the design as simple as possible, but of course there are modifications possible. You could add a switch for 1 player mode closing the Player 2 button permanently. Or you could set up the circuit to avoid cheating (in my version it is possible to push and hold the button to bounce the ball back). What ever you do, please share your modifications!

...and have a lot of fun!

Make It Glow

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