829Views15Replies

Author Options:

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

15 Replies

user
Jaycub (author)2009-01-30

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.

Select as Best AnswerUndo Best Answer

user
comodore (author)2009-01-17

What you need is an H-bridge, that's just the thing used in toy cars, so it can go forward and reverse.
Here is an Instructables on how to make it.
https://www.instructables.com/id/How-to-make-an-H-bridge/

Hope it helps! :D

Select as Best AnswerUndo Best Answer

user
Flark (author)comodore2009-01-23

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

Select as Best AnswerUndo Best Answer

user
comodore (author)Flark2009-01-25

ok, just trying to help. :D

Select as Best AnswerUndo Best Answer

user
apple perez (author)comodore2009-01-30

more about transfer switch

Select as Best AnswerUndo Best Answer

user
Padlock (author)2009-01-22

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

Select as Best AnswerUndo Best Answer

user
Flark (author)Padlock2009-01-23

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

Select as Best AnswerUndo Best Answer

user
gmoon (author)2009-01-05

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

Select as Best AnswerUndo Best Answer

user
Flark (author)2009-01-05

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 :)

Select as Best AnswerUndo Best Answer

user
11010010110 (author)Flark2009-01-05

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

Select as Best AnswerUndo Best Answer

user
NachoMahma (author)Flark2009-01-05

. 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.

Select as Best AnswerUndo Best Answer

user
11010010110 (author)2009-01-05

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

Select as Best AnswerUndo Best Answer

user
NachoMahma (author)2009-01-04

. 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.

Select as Best AnswerUndo Best Answer

user
Tanners (author)2009-01-04

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.

Select as Best AnswerUndo Best Answer