Picture of The Most Useless Machine EVER!
And yet everyone wants one!!!?

AKA:  The Ultimate Machine!

Get Your Parts Kits and Machines: FrivolousEngineering.com

Update Oct 31, 2012:

Now Available At the Maker Shed

"Weird Al" Yankovic Sez:  "I never realized till now how much I needed one of these."

AS SEEN ON TV!  Make Magazine's amiable editor-in-chief, Mark Frauenfelder demonstrated The Useless Machine on the Colbert Report!

Useless Machine Featured in Vol 23 of Make Magazine!

Thanks everyone for all the cool comments, suggestions and all the videos! Keep 'em coming.

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Step 1: Background

Picture of Background
Also known as The Ultimate Machine: Claude E. Shannon built the first one based on an idea by Marvin Minsky.

After seeing a video of such a machine I just had to have one of my own.

The only design I could find uses a PIC microcontroller but I consider this to be overkill (not knowing how to write code for micros may have had some influence on my humble opinion...).

Additionally, the microcontroller version really doesn't shut itself off. It's circuit remains powered even when the switch is in the off position.

Knowing a little bit about servos and basic electronics, I felt sure that I could build the machine using a simple analog circuit.

My main goal however was to have the machine REALLY turn itself off.

The machine in THIS instructable accomplishes that!

Step 2: How Does It Work?

Picture of How Does It Work?
Inside the box is an geared motor powered by double A batteries and two switches: a toggle switch on the top of the box and a micro-switch inside. That's it.

The switches are positioned to be limit switches for the motorized arm. The toggle causes the motor to reverse, while a micro-switch powers down the circuit when the arm finishes retracting back into the box.

When idle, the circuitry is fully powered down. The toggle is “Reverse” direction, and the micro-switch is being held in the off position by the servo arm.

Keep in mind the micro-switch is wired up so that it works completely opposite from a normal switch like you would find in a doorbell. By using the common pin and the normally closed pin the micro switch is “OFF” when it’s button is being pushed.

When a person turns the toggle switch to the forward position, it also provides power to the motor causing it to rotate the arm towards the toggle switch.

As the arm moves away from it's off position it releases the micro-switch providing the backup power needed for the motor to retract after the toggle switch is turned off.

When the toggle gets switched “OFF” it actually reverses the motor’s direction. The arm reverses direction returning towards it's 'OFF' position. When the arm runs into the micro-switch it stops.

The toggle switch needed is a Dual Pole, Dual Throw (DPDT) toggle switch. This type of switch is actually a pair of switches which operate together (Dual Pole) and both are On-On (Dual Throw).

Step 3: More details

Picture of More details
When I originally published this instructable I used a standard RC servo and a simple control circuit using a 555 timer in the photo above.

Compukidmike was quick to point out that by modifying a continuous rotation servo (basically just using the the servo as a geared motor) and using the same switches it wouldn’t require ANY control circuitry.

Much simpler and just about any geared motor or a modified standard servo can be used. Start looking through your junk pile because Useless Machines have even been made from CD/DVD drives.

So you have a choice. Step 5 is the easy method.

If you prefer to use a standard unmodified servo then follow steps 6-9

Step 4: Parts

Picture of Parts
Sourcing all the parts in one place can be difficult.  If you don't mind modding a servo then everything you need is at Newark/Element 14 and the parts are listed below.

If you would like a complete kit with case, please check out our Ultimate Useless Machine Kit as show in the photos above.

It includes:
Gear-Motor (no modding needed)
Printed Circuit Board making soldering very quick and easy.
Laser-Cut acrylic actuator (Finger) back-lit with LEDs
laser-cut acrylic case & hardware
Switches, LEDs, wire and heat shrink

The kit is a big improvement over any of our competitor's machines.  They don't supply a printed circuit board or the nifty acrylic finger that's back-lit with red & green LEDs.

All the acrylic parts are laser-cut at our shop using a Epilog laser!

We also sell just a Parts Only Kit for those who wish to make their own case.

Frivolous Engineering buys parts from Newark/Element 14 & you should too!

Here's the parts you need to build the original Useless Machine:

Battery Holder 2-AA Cells (Note: 3 AA's or even 4 AA's will work, faster, maybe too fast )
DPDT Toggle Switch
SPDT Micro-Switch  (Just about any with 3 pins and a lever should work.)
RC Servo you can mod


The servo I modded is a JR Sport ST47. It's a standard size servo with a torque of 55.0 oz-in.

Stay away from any of the micro-sized servo’s. A standard size servo with at least 4-5Kg/Cm torque will work in most cases. Keep in mind that the toggle switch and arm length are some of the things that will determine how strong a servo you’ll need. Most of the standard servos should do the job.

mrrigsby reports that a toggle switch from Radio Shack, catalog # 275-636 works.

He also pointed out that it's better to use "4 fresh alkaline batteries--with 4 rechargeables, I couldn't depend on having enough power to always throw the switch."

Step 5: Wiring Diagram

Picture of Wiring Diagram

First you will need a gear motor. 

If you wish to modify a standard RC servo for your geared motor then follow this 'ible: 

If you use a Parallax continuous rotation servo there is no need to modify the gears, but you will have to modify the wiring to the servo's motor.

The diagram above indicates how you will wire the motor, microswitch and battery pack to the pins on the toggle switch.  This is called 'Dead-Bugging' and is a prototyping method from way back.

It's a very simple circuit but it's easy to mess up the wiring.  Follow the directions carefully or purchase the Useless Printed Circuit Board from us to speed up and greatly simplify the wiring process.  And a cool LEDs to the circuit too.

Wire the gear motor to the indicated pins.

A short length of wire connects opposite pins on the toggle.

Another wire connects the other outside pins on the toggle and this wire has the microswitch in-line.

The battery pack goes to the other remaining pin on the toggle.

If you find that the motor is running in the opposite direction from what is needed, simply reverse the wires going to the motor.

tydarby posted the great graphic below, showing how wire up a modified servo .  The pins to use on the micro-switch are the common (C) and normally closed (NC).  Nothing should be connected to the normally open (NO) pin.


Batteries: The original parts list used a 4 AA holder but you may find that 4 batteries driving the machine makes for way too fast operation.  Blink, and you'll miss it.  

In most cases you should be able to get away with just 2 or 3 AA batteries, making the overall action more slower, and more visible.

Keep in mind that the our kit only uses 2 AA batteries.

More on Motors:
I originally chose to use servo's because they are available almost everywhere, and are standardized, but you don't have to use one. Just about any motor should work, as long as it's geared down, and has enough torque to flip the switch.

The more salvaged parts you use, the better.

Keep in mind that another reason for using a geared motor is to prevent bounce-back from happening when the machine shuts off. Without the gearing, motor wouldn't keep the arm pressing down on the micro-switch while it's off. The machine's arm would just keep hitting the switch, turn off then on, then off, then on....

The next couple of steps show the original way I made my machine.  If you're building one using the information above, then SKIP the next 4 steps and jump to step 10.

Step 6: Original Design Using 555 Timer

Picture of Original Design Using 555 Timer
For ease of construction, I highly recommend going with a modified servo or a gearbox motor instead of using the 555 timer circuit show below.� There is almost nothing to be gained, or any improvement of operation of the machine using this circuit and a standard servo.

Some drawbacks in using the timer circuit are:� you have to use a 4 cell battery pack.� It won't run on any less voltage.� This will ensure that the servo will run very quickly, sometimes too fast in my opinion.� Using a modified servo, you can use 3 or possibly even only 2 cells, making the machine run at a slower, more spookier speed.�

Another drawback of using the 555 timer version is placement of the mechanical parts are limited due to a standard servo only having 180 degrees of rotation.� Using a modded servo or gearbox/motor will allow easier design and placement of the parts.

The only advantage with using a standard servo and the circuit is that just about any servo can be used, and if it should break or wear out, replacement is simple.

But when pondering the concept of the Useless Machine, perhaps going with the most complicated version is the aesthetically superior choice. � �

Note:� if you need more rotation from the servo, change R3 to 10K.

sirus20x6 edited the 2nd schematic putting the pins in order.
colin55 provided the 3rd version.

All of the schematics are basically the same circuit, just arranged differently.

Step 7: Original Parts List

If you wish to build the more complicated, yet cooler dead bug circuit this is the parts list:

Revised Parts List Feb 27, 2010 , including the digikey part numbers.

Servo 900-00005-ND

Battery Holder 4-AA Cells BH24AAW-ND

NE555P Chip 296-1411-5-ND

C1 0.1 uF Capacitor 478-1831-ND

R1 220K resistor CF1/4220KJRCT-ND

R2 27K resistor CF1/427KJRCT-ND

R3 15K resistor CF1/415KJRCT-ND

D1 1N4148 Diode 1N4148FS-ND

DPDT Toggle Switch 450-1533-ND

SPDT Micro-Switch EG4544-ND

Cost: around $25.00

Step 8: Breadboarding:

Picture of Breadboarding:
BB CU.jpg
If you're going to use a standard servo and 555 timer, it's best to test things out first on a breadboard. The photos show exactly how it's wired up.

Also, if soldering isn't your thing, then this can be your finished, working circuit. Just keep in mind that it's very easy for wires to be accidentally pulled out.

Step 9: Dead Bug Circuit Construction:

Picture of Dead Bug Circuit Construction:
Toggle CU.jpg
The circuit has very few parts so instead of making a circuit board or using a prototyping board I just soldered most of the components directly to the appropriate pins on the 555 chip.

This method of prototyping is called Dead Bug construction.  As the name implies, the finished results aren't very pretty and often resemble a dead bug.

You’ll need a fine tipped soldering iron, steady hands and basic soldering skills.

Keep in mind that you don’t have to dead bug the circuit.  Prototyping or perf board can be used for the final circuit, or just keep it on the half-size breadboard that you tested it on.

Step 10: The Box

Picture of The Box
I don't have much skill in wood working so I was fortunate to find a ready made box at the Dollar store. 

Also, you can get really fancy wooded cigar humidors that make for a great box.

The box you use need only be big enough to fit a battery pack and servo.  The one I used was about 5x4x3 inches.

I removed the latch that came with it.  The lid was carefully cut down the middle and the hinges were move from the back to the side.  A hole for the toggle switch was drilled in the other part of the lid about an inch from the cut side.

Step 11: Putting it All Together

Picture of Putting it All Together
I’m finding this part very difficult to explain, so if you’re having trouble understanding things, let me know…

The micro-switch will only shut off power when the toggle switch is in the OFF position.

Before you start installing the parts in the box, you'll want to make note of the direction the motor turns and in which position of the toggle switch is off.

Mount the toggle-switch and now you can align where you are going to mount the motor and design the shape of your arm.  Design the arm so that when it's in the off position, it will hold the micro-switch OFF.   You may need to build a stand-off for the micro-switch.

Before you put in the batteries, manually move the arm to check that it will rotate between hitting the toggle, and hitting the micro-switch.

If you are using a standard servo and 555 circuit the idea is the same.  The only thing to keep in mind is that the servo arm can only rotate at most 180 degrees.

Once you have the parts installed and aligned there is some fiddling.

Power up the circuit but leave the arm off of the servo.  Flip the toggle to the ‘on’ position and the servo “axle” rotates to the on position and will then stop.

Now take the batteries out of the circuit and flip the toggle to the "OFF" position.  Now put the plastic actuator (with the wooden arm) back on the axle so the ‘hand’ is touching the toggle switch.

Put the batteries back. The servo will return to it’s “off” position.

Now you can see if the arm is fully retracted back into the box.  I had problems with the arm sticking up to high, not allowing the lid to fully close.  Or having the arm hitting the bottom of the box.

At this point I had to tweak the shape/dimensions of the arm.

Once I had the arm switching the toggle, and retracting back into the box I mounted the micro-switch so that when the servo is in the "OFF" position it is holding the microswitch down.

At this point you should have a working Useless Machine.


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Meuryn4 years ago
Just a question about the wiring diagram, where the lead from the microswitch crosses over the lead from the the servo there's that 'bump' symbol. Is that just there to tell you the wires cross over or do I need to make a junction between the two wires or something different? Sorry, relatively new to all this.
mrmerino Meuryn3 years ago
Protip: the actual symbols for different things will vary according to who created the diagram, but basically, whenever you see that bump over the wire like up there, you can always assume that those wires don't connect.
Frivolous Engineering (author)  Meuryn4 years ago
It means the the wires are NOT connected, one just passes over-top of the other wire!
Good, thankfully I did wire it the right way anyhow.
Lol cool project
There are a lot of videos with useless machines on youtube similar with this. But elufo below has the gratest ideea with the "infinite version" lol :)))
ionutpop3 years ago
As you said, you have to appreciate the irony of such a device.

But this time I got to admit that I don’t understand the logic of this viral meme. I’ve been receiving the same link today from several directions. Nobody seems to care that it’s not a new gadget, and not a new joke. Usually the web is full of bitter commentators about “how that’s so last season”. If you bother to google with Shaude Clannon original title “The Ultimate Machine” you will find several of these.

Perhaps the best lesson is that anything (even old stuff) can become a great viral if it just hits the right people, right channels. (twitterists with influence etc.) As said by smarter people than me, meme’s (or gene’s) success is not dependent on whether it is a good meme but just in the replication efficiency.

Ionut from bwin
I really like this but made a useless squared without using two machines.
Thoth5053 years ago

I;m just wondering what the black and silver thing is at the top of the image, one of the yellow wires go to it. Thanks!
Frivolous Engineering (author)  Thoth5053 years ago
That's the diode.
Isn't that a bit to big for a diode, i can see the diode next to the resistor. Is there two?
ldiener3 years ago
In the notes to step 4, there's a reference to "wiring to the motor". There's a nice 'ible on doing this at http://www.instructables.com/id/Remove-a-Servo-Controller/#

This reference helped me future out what that comment meant.
so i wired mine exactly like the diagram and the second i flipped the switch, the servo literally started spitting smoke and burned up! i have no clue what happened?
I had this exact same thing happen today. Did you ever figure out the cause?
Most likely something shorted out in the servo. What brand and model servo did you mod?
lukeD4 years ago
what if you are faster than the robot, and turn it off by yourself?
Frivolous Engineering (author)  lukeD4 years ago
Same as if the machine switched it: the arm retracts back inside the box.
Derpancakes4 years ago
LOL i love this!!!
ginger200374 years ago
Okay, I admit it, I loled at this xD it's so funny, but very cool
eatramen4 years ago
very cool and entertaining for a "useless" machine haha!
flydogfly4 years ago
Wow!, you wont believe this, I saw a video two days ago of a Most Useless Machine, but after a while it strated running around crazy, anyways point being I made one yesterday using my Lego Mindstorm. Cool instructable
sirfag5 years ago
thanks mate it works great exept i need a box
I just bought a nice little box over at Lowes. It's a kids "build it yourself" Jewelry Box. It only cost $8. It's precut pieces that you just tack together. May be a little tight with all the wires.....
I just finished mine, and I have to say the box was the hardest part, well making it look good was hard anyway. (I made mine from scratch.) I think going SaskView's route might be better.
jmartin184 years ago
it looks like the yellow is connected with both resistors at the top left corner post. Is this correct, because it doesnt seem in line with the diagram for wiring.
That is correct. The yellow wire is Vcc. The way I've laid out the circuit on the breadboard may look different, but it's the same circuit as in the diagram.
00bunge004 years ago
I saw a related video on you Duelling Useless Machines video about a laser triggered camera setup? Is there a page about that on here? if not, could you send me a design for it?
klio9114 years ago
So, I'm trying to build one of these things. I bought all the parts last year, before the kit was available and am just getting around to building now. I am so new to this that I think my question is too basic to be found on the internet (or I'm asking it wrong).
It is: how the hell do you connect the servo to the circuit? Is there a part that I'm missing? I know there's a servo connector available for breadboarding, but what do you do when you want to solder everything together? I feel like there's a component that needs to be added here, and have no idea what it is.

I feel like a doofus for not being able to figure this out on my own...any help would be greatly appreciated.
Frivolous Engineering (author)  klio9114 years ago
I used the female half of a servo extension cord on the first one I built, but have also just soldered in the servo wires permanently on other builds.

The servo I bought ends in a female connector...so I should be plugging it into some kind of male piece? But what?

I don't trust my soldering skills enough to cut up my servo yet...
Frivolous Engineering (author)  klio9114 years ago
My mistake, it WAS the male end that I used. Very embarrassing getting the gender mixed up. So of course, use the male half of the extension cord...

jmartin184 years ago
hard to tell whats going on with the toggle switch, I'm at the point of connecting it, and I can't figure it out by comparing the picture and mine.
Had fun putting together the useless machine kit (my first time soldering) ... But after about 15 or so switches there's a faint burning smell and brand new AA batteries are totally drained in an hour - I'm pretty sure that's not part of the design ... Any notions on the problem? I'm very new to hobby circuitry like this ...

Sounds like you've got a short somewhere. Carefully check you wiring and soldering. Make sure none of the pins on the toggle are shorted together.

Also make sure you are using the C and NC pins on the micro-switch.

Let me know if you still can't find the problem.

mvan dalen4 years ago
this is what men call useless..i think without a battery it's usesless
On my motor, it has a red, white and black wire going to a plug. for this do i just cut off the plug, strip the ends of the wires and use the red and black ones? (ignore white?)
Follow these directions for modding it into a gear motor: (http://www.instructables.com/id/How-to-modify-a-servo-motor-for-continuous-rotatio/)

I have the motor, and it has 4 arms on it. do i sand the 3 down that i am not using?
That's up to you. If they get in the way, or if they aren't needed then sure. The way I arranged things in the photo on this page, I'm using one of the arms to activate the micro-switch, and I've cut off another that would be in the way.
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