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The Most Useless Machine EVER!

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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: 
http://www.instructables.com/id/How-to-modify-a-servo-motor-for-continuous-rotatio/

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.

Notes:

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.

 
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Meuryn3 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 Meuryn2 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)  Meuryn3 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.
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?
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/)

my microswitch is not shutting off the circuit! ive tried three of them...any suggestions?
Are you using the N and NC pins? Double check your wiring.
jonnyman8883 years ago
Hey, i was wondering how i modified the wiring for the servo? I'm using this servo: http://www.oomlout.co.uk/index.php?main_page=product_info&products_id=235 Do i just need to cut the white wire or what? Thanks a lot :)
nromano23 years ago
I wired everything just like in the diagram however when the toggle switch in one direction spins the motor and the lever switch stops it (as it should) however the toggle switch in the other direction does nothing any idea on what I am doing wrong?
bobdoy3 years ago
hello-I built the thing and had the problem of one of the batteries exploding and spitting acid everywhere. Very Scary-I took the battery out and noticed I put the damn thing in the wrong way cause I was so excited to finish it. Well I cleaned up everything and then put the battery in the right way and everything was moving very slowly. Then started to smoke and the batteries got super hot again. do you think when I messed up and put the battery in the wrong way that I messed everything up or just the battery pack. I know I have to get a new battery pack because it is melted. but I want to make sure I dont screw this up again any thoughts?
kcdecker3 years ago
And just for fun, I added a styrofoam ball into the box in which I embedded a couple of small green LEDs (for eyes) and one of those recordable birthday card things. When the switch is thrown, the arm opens up the box as usual, but also the eyes light up, and the voice says "LEAVE ME ALONE!"
maxpower493 years ago
so is this just two switches and a servo or is there still some other parts needed
Just two switches and the (modified) servo. And the battery pack, of course. And a little extra wire and your soldering iron. That's all I used to make it work.

Just a little clarification on the modification of the servo. If you use the suggested parallax servo, it comes with three wires attached to it, red, black, and white. These are attached to a small circuit board inside the servo housing. You'll have to take the servo apart and basically remove the circuit board and connect the red and black wires directly to the servo motor.

The instructions on how to do this are listed in the URL in step 5 on this page. It's pretty simple. Just un-solder the terminals that connect the motor to the circuit board, take out the circuit board, and connect the red and black wires directly to the motor. Done. Now you have a continuous rotation servo.

Also a little clarification on the wiring diagram. I'm somewhat of a newbie so it took me a while to get it. In the diagram, the black line running from the upper right terminal to the lower left terminal on the toggle switch is a jumper wire. Don't forget to add that one in there.
Frivolous Engineering (author)  kcdecker3 years ago
Good points!
kcdecker3 years ago
Well it took me a while to figure out what the directions and the wiring diagram were trying to tell me but I finally got it. Brilliant! I haven't even put the box together yet and I'm already laughing. Thanks!
If we are modifying the servo- connecting the wires directly from the DPDT Toggle to the motor of the servo- then why cant we simply use like a 1.5V motor instead?
I 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 machines arm would just keep hitting the switch, turn off then on, then off, then on....
could i just use a high trottle motor with a gear box because i saw the link on how to modify a servo and its bacicly a motor with a grear box. thanks :)
sirfag4 years ago
the link you give me for the servo is really good i recommend you use this link because it works (to modify the servo)
weinerpoop4 years ago
Do you also connect (+) to both servo signal AND servo (+)? I'm using the parallax continuous rotation servo, btw. Also..just need a bit of clarification here..on the micro switch do we just put (+) power on NC and C (no ground connection) thanks in advance.
whereami4 years ago
With the SPDT Micro-Switch EG4544-ND from digi-key am i meant to solder on 2 wires to the metal holes? the picture looks like there should be 6 metal poles. sorry about the terminology, don't know a thing about electronics.
MS0850503F010S1A.JPG
Frivolous Engineering (author)  whereami4 years ago
3 pins are correct for the micro-switch (the toggle-switch is the one with 6 pins). The wires don't have to go in the holes but it makes it easier when you solder them.
G.J. Dyason4 years ago
I have all the parts but I'm not sure witch wires are witch at the microswitch (in the picture) is the left the NC or C connection? My switch looks a little diffrent.
xxaznitexx4 years ago
Is it possible to use this motor, HSR-1425CR (Continuous Rotation), to construct the circuit? Or do I still have to modify it?

http://www.servocity.com/html/hsr-1425cr__continuous_rotatio.html
monboy104 years ago
this works great i built one this way and was super simple and i am only 13 years old. it took  lots of tweaking but it was awesome when i got it right. it works fine until someone get scared and drops it :( oh well it simple to fix.
jeremys984 years ago
what does the white wire do on the parralex servo motor
ab3124 years ago
the original wires from the servo when you put them on the motor can you cut the connecter piece off of the wires and use them as hook up wires.
Samamam4 years ago
hello, does this circuit completly eliminate the need for all of the other components like the resistors and capacitors?
Thanks
Frivolous Engineering (author)  Samamam4 years ago
Yep!  Just wire it up like in the diagram.
dumes794 years ago
If I was going to use the modified version without the electronics could I just use a DC motor instead (like the one in an old VCR) with a gear glued to the shaft?
jmartis0044 years ago
I decided to try the modified circuit but when I toggle the switch nothing happens. Everything looks to be wired okay and the batteries get hot but thats it. Any suggestions?
doryrhp4 years ago
I built my box with this circuit and the "modified" servo motor at the link below:

www.hobbyengineering.com/H1210.html

This motor is fast and has lots of torque running off four AA batteries.