SIMPLE Polarity Reversing switch

First thing first, I KNOW there are other instractables for this, I just wanted to show my version. PLEASE don't flame because it's already been done!

Second, this is my first instructable. I have writen another but do not have a camera to take pictures with so cannot yet post it.

Third, this uses the simplest Double Pole Double Throw switch. This requires nothing more than the switch and some creative wiring. Please note that the "off" position only works if you have a "center off" switch! A DPDT relay can easily be substituted if you have one. If you want a 'struct' on this, leave me comments.

[EDIT, 3-28-'09] I have added some new information, please see the new step 4.

Step 1 Selecting your switch

You need to decide if you want to purchase a switch or salvage one from something else. if you purchase one, you have more options as there are many out there. if you salvage one you are limited to what you can find.

Make sure the switch you use can handle the amount of current you need
Decide if you want an off position or not.
Decide if you want a sliding switch, a toggle switch, rocker switch, or even a spring loaded switch that returns to off when released.
If there is a junk car around, check it for power window switches or electric seat adjusters. Both are most often DPDT switches, some are already set up to be inverting switches. Don't forget to steal the motors or sometimes linear actuators out of the seat adjusters, if you can!!!!
Broken stereos commonly have one or two switches in them

If you salvage a switch, the first thing I would do is test ACROSS the switch to be sure it is double pole. The switch has two rows of contacts with three pins per row. NO pin in one row should have continuity to ANY pin in the OTHER row. In the "center off" position, if equiped, NO TWO PINS should conduct.

In the case of a sliding switch: You should find that the center pin in each row conducts to the pin at the same end that the slider is on, but will not conduct to any other pin in the same row or to any pin in the other row.

In the case of a toggle switch: You should find that the center pin of each row conducts to the pin at the end OPPOSITE to the toggle lever, but will not conduct to any other pin in the same row or to any pin in the other row.

In the case of a rocker switch: You should find that the center pin in each row conducts to the pin at the same end of the switch as the RAISED side of the rocker, but will not conduct to any other pin in the same row or to any pin in the other row.

Comments

[head scratcher]

Great info. Due to my lack of knowledge, you lost me on the alternate wiring scheme. But the initial crisscross plan makes sense to a rookie like me. I have a 110v hoist which I am converting to a luggage lift and need to incorporate two more controllers on each floor. From the source the WHT wire leads up to the motor, and a black wire is directed to the up/dwn controller w/ rocker switch. The rocker switch is wired differently. There are four wires connecting the switch. The BLK (hot wire?) Using your pin enumeration; is connected to pin #5 , a WHT wire from pin # 2 leads to a set of capacitors? A RED wire connected to the pin #6 runs to a limit switch (that cuts out power when the cable reaches the top) the same red wire from the limit switch joins with the wire from the capacitors, and continues to the motor. and finally a GRN wire joins pins 4, 1 and 3 then runs up to motor. My questions; are all DPDT rocker switches the same. If I find one (here in Mexico) could I simply splice in an additional two switches following the same schematics of the original switch? Thank you.

[GreenAce92]

I plan on using this for a simple robot where this would be applied for "feelers" where it would be going straight then when a feeler is pressed(via contact) it would reverse that motor causing it to turn away from object if it all works anyways ;) thanks and nice job

[varun17]

sir may i know the wiring connections using 2 dpdt switched as i want to control a simple 4 motor wired robot

[DieCastoms]

Just use one switch for each pair of motors. The wiring will all be the same as I have shown. You can connect your motors in series or in parallel. Parallel will give you more speed, and series will give you more power. Since I have recently located a drawing I did some time ago, I will post another instructable shortly showing a way to switch whether two loads are wired in series or in parallel, this way you can choose "high" or "low range" for your robot, for each set of motors. Hope this helps, Mike, from DC.

[varun17]

sir kindly send me the mail as u said u would about pairing 2 loads i series and parellel in 4 motor robot

[DieCastoms]

As my previous comment states, I will post another instructable here shortly. If you subscribe, you'll get a notification of my posts. Mike, from DC.

[DieCastoms]

Ok, I've gone and done a new 'Ible for the series/parallel selector switch.

It can be found here:
http://www.instructables.com/id/SIMPLE-ParallelSeries-Select-Switch/

I hope it is what you needed.

I will post a diagram there as a reply if you need more help varun.

Mike, from DC.

[stuartkeane]

Great, I will use this on my caravan when I am traveling to Europe where the are not consistent with polarity Thank you

[DieCastoms]

I don't know anything about electricity overseas other than it follows more than one standard. If switching polarity is all you need to do, this switch will do it, HOWEVER: Be sure to use a switch rated for the current you will be switching! A 12 volt switch WILL NOT switch 220 mains current. If your caravan pulls 500 watts, be sure to get a switch that can handle more than that. Some appliances draw FAR more current than their listed ratings while starting up.

[magillagorilla]

Thank you. I especially found your clarification that the load and source wires can be swapped very helpful. I have a question: I have an old Bodine 4 wire reversible motor (2 black wires and 2 blue wires) and their schematics for it say to transpose the black leads to reverse the motor. One of the blue wires shows a fixed capacitor on it. How do I wire 4 leads from the motor onto this type of switch? Thanks

[DieCastoms]

I'm sorry I have never responded to your comment, I don't know why I had not seen it. PLEASE take this as a possible suggestion and not a final answer. Most likely what you have is the blue wires power one set of electro-magnets in the motor and the black wires power the other set. Switching the polarity of either set will cause the motor to run reversed. Switching the power of the blue set may destroy that capacitor you mentioned though, so leave the blue set alone. My switch does exactly what your instructions say, transposes two wires. Leave your blue wires connected the way they are and follow my instructions with the black wires as though they were the only power to the motor. If your black wires are already connected from a source to the motor, I would either cut them (or better yet disconnect them from the source or the motor and add new wires) to put my switch between the sources and the black wires to the motor. Again, as I know nothing about your specific motor or application, please use this as a suggestion and not as a definite answer. Hope that helps, DC.

[prabandhchakraborty2]

sir can I know the circuit arrangment of relay if Ihave to provide for 2 switches?

[DieCastoms]

I would be happy to, but what do you want the two switches to do? If you want one for forward/reverse select, and the other for stop/go (the arrangement in most "Power Wheels" toys), simply put a single pole single throw (SPST) switch in the positive line from your power source. Does this answer your question? DC

[leevonk]

nice little instructable

[DieCastoms]

Thank you very much. I appreciate your compliments. Is there something I could do, in your opinion, to improve it? Mike, ac DC.

[leevonk]

not really, the little circuit diagrams are all that's really needed. maybe put them all in one big picture or something, but that's not needed.

[joe57005]

That's called an H-bridge. (the circuit diagram would look like an h) i used to make these all the time to control small motors.

[guyfrom7up]

ehhh... Hibridges usually have transistors or relays. Good instructable! I did something similar to this a couple of months ago when I made a solar car. The switch controlled the solar panels to either to be wired in series or parallel.

[DieCastoms]

Thank You both for posting. I was always under the impression that an H-Bridge was this sort of thing but done with FETs, not with actual mechanical switches... guyfrom7up, your comment touches on my next instructable, a wire harness for two motors (or batteries) to select between low and high speed (by putting either two motors or two batteries into series or parallel mode) as well as the reversing switch. DC Mike.

[Pazzerz]

This is what I was trying to get across in my instructable. Your assumption of the FETs is what the usual person thinks on these days, when actually its been done, simpler and less expensive than using many parts to do the same thing. We have to remember that electronics as we know it today is an evolution of the original stuff. Good to see you're thinking. Also, the wiring harness: think about the way a stun gun charges and discharges. One is in parallel the other is in series. You may want to try a watered down version for a quick kick in the motor (as long as it will withstand the kick!).