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Building a switch to invert current Answered

I got a small electrical engine the other day, and I have to hook it up to two switches so that one switch starts the engine clockwise and the other counter-clockwise. My initial thought was to simply hook it up to two separate batteries each with a switch and one with the current reverted (like illustrated). But I'm wondering if there's a better way to go about this. For instance I have no idea if accidently activating both switches simultaneously will blow up the engine :s



9 years ago

Don't worry, if you turn on both switches in this circut nothing bad would happen to the motor. It would just be shorting-out the batteries in series.

This does look like exactly what I need :) thank you for the suggestion (thanks to gmoon also).

ok, just trying to help. :D

Ignore the schematic I made above, if you already read it. It doesn't work!

That's fine. Thanks for the help :) I've done a temporary solution like the one I sketched but will look into the H-bridge for the final solution


9 years ago

You might search on instructables (or elsewhere) for H bridge, there are several examples...


9 years ago

Thank you for the suggestions. I do need the two switches to be separated though as they need to be pressed in two physically different locations, so I'm not sure if the DPDT-switch would work. I've found some schematics for DPDT switches, so will look into those to see if the logic can be transferred into something home-made. Again, thanks for the suggestions :)

you can do like this. youll need 1 dpdt (6 entries) (simple 2 state one without center off) and 1 simple switch (2 entries) each switch makes the motor work in 1 direction when both switches are on the motor just defaults to 1 direction if you want it to be off when both are on you need spdt (3 entries) instead of the simple switch


. You can use two DPST switches, but you will lose the "interlock" feature (you will be able to close both switches at once). . The wiring is much simpler than it appears at first glance. You just have to look at it for a while. The X that BinaryBoy mentions is what swaps polarity. . If you are familiar with house wiring, a three-way switch is a SPDT. Glue two 3-ways together (and bond the toggles together) to get a DPDT.

do what NM said

the switch comes with 6 entries. connect the corners with the opposite corners in like X. connect 2 wires from something A to the 2 wires of the X. connect 2 wires from something B to the 2 center entries on the switch

it does not matter if A=battery B=motor or the other way

for your second question : motor wont get damaged. batteries yes and possibly wires and switches yes too

. You can do it with a DPDT (double-pole, double-throw) switch. If you want to use the same switch to turn the motor off, specify "center off" (so that would be a DPDT with center off switch.*

*Not a recommendation, just close to the top of the search results.

well you don't have to use 2 batteries but yea that seems like the easiest thing to do and my advice would be don't put both switches on at the same time i don't know what will happen but it probably isn't good for the motor.