Useless Game

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Introduction: Useless Game

This is my take on the Useless Machine/Box (or Ultimate Machine - originally invented by Claude Shannon) that switches itself off if you turn it on. In this case you can play a game against the machine that will always result in a draw or win or lose - I'm not sure which one.

The components are a box, servo, Arduino Uno and a magnetic or reed switch that detects the presence of a magnet.

I know, the Arduino is such overkill but they are so cheap here ($2.00) - probably a good project for a Nano.

Ok, guess I have to explain the two dollar Uno. This particular board cost me $6 (35rmb) on but I said $2 because I have five clone boards (dccduino) that I also got on taobao for 15rmb (actually $2.50) each but didn't even notice I used the $6 board. So the devil is in the details. Sorry I stretched the truth, told a fib, lied a bit. (

I will try to be more careful and detail oriented in the future and less prone to exaggeration.

On a different note: a real useless machine actually turns off it's power (as I understand it, I haven't built one) and this one does not do that.That would be cool because this one you have to unplug the power or battery or install an on/off switch. Would be cool if this one turned off the power too with some kind of magnetic switch or something but

then the Arduino would have to init each time - not sure how to approach that.

Step 1: Set Up Servo Arm With Magnet

I just hotglued a piece of chopstick to a servo arm with a zip tie. Then hotglued magnet to the other end.

Step 2: Mount Servo in Box

Here I glued servo to the inside of a plastic box container so the magnet is just below the "game board" drawn on the outside of the box.

Step 3: Mount Magnetic Switch and Connect Arduino and Servo

Then hotglue the magnetic switch (I used old bicycle speedometer reed switch) centering one end below one of the playing squares.

Plug one end of magnetic switch to digital port 2 and also to a 1 k resistor then to ground.

Plug other end of magnetic switch to 5 vcc.

Plug servo signal to digital port 9.

Plug servo positive to 5vcc.

Plug servo ground to gnd.

Step 4: Arduino Uno Program


Servo servo1;

const int buttonPin = 2; // the number of the pushbutton pin

const int ledPin = 13; // the number of the LED pin

int buttonState = 0; // variable for reading the magneticswitch

void setup() {


// initialize the LED pin as an output:

pinMode(ledPin, OUTPUT);

// initialize the pushbutton pin as an input:

pinMode(buttonPin, INPUT);


servo1.write(55); }

void loop(){

// read the state of the pushbutton value:

buttonState = digitalRead(buttonPin);

Serial.print(" button= ");


// check if the pushbutton is pressed.

// if it is, the buttonState is HIGH:

if (buttonState == HIGH) {

// turn LED on:

digitalWrite(ledPin, HIGH);





delay(2000); }

else { // turn LED off:

digitalWrite(ledPin, LOW); }




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    can you give me a link to anywhere that sells good reed switches that can be used here (the best thing could be in amazon) thx ;).

    Sorry I can't as I am not in US. But I believe that just about any reed switch will work.

    This is really nice twist on the useless machine!

    Thank you. Yeah, I tire of this game pretty quickly.
    Claude Shannon who made a useless machine from Marvin Minsky's idea also built the first robotic juggling machine. I tried to build one but failed but did manage to build a bouncing juggling machine.
    Kind of run out of ideas lately to work on.


    I currently live in china and I also use taobao.

    things are very cheap!

    I love it! A great idea and simple too. Thanks for sharing.

    An Arduino compatible (called an "Eleven") in my country is $49.90

    If you can get the genuine thing for $2.... just start exporting.
    Stick a sticker or something on it and call it your own product.

    50 bucks,that's crazy. Yes, things here on are really cheap. Electronic products in general are really cheap. I went into an electronics market in Harbin and saw people putting little circuit boards together by hand, including hand soldering those dinky little caps and resistors, and then sell the product for next to nothing. I think those days may be coming to an end though. Cracking down on knockoff products here.

    This is great, but I have a question: where do you get Arduino for $2??

    His bio says he is in Shaoxing... which would explain that!