DPDT switch wiring help

Thread Starter

91five0

Joined Jan 19, 2021
24
followed several diagrams, and can not seem to get something right. use the switch to switch polarity on a small 12v motor. when hooked up how the diagrams show I have nothing. I can move the input + and - to get cw and ccw rotation in the off position and off in the on positions, but not on off on. I'm putting power in and ground to NO, motor power and ground to to NC and crossing sides to C.
 

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dendad

Joined Feb 20, 2016
3,835
You could try---
DPDT_Motor.jpg
BUT, is your switch a center off version?
And, yes, it is actually drawn on the back of an envelope ;)
 

dendad

Joined Feb 20, 2016
3,835
Just while testing, add a lamp in series to save fuses.
I use Polyswitches now in place of fuses as when they cool down, they reset.
 

Thread Starter

91five0

Joined Jan 19, 2021
24
Just while testing, add a lamp in series to save fuses.
I use Polyswitches now in place of fuses as when they cool down, they reset.
that's a good idea, I'll have to see what I have laying around. I'm not much of an electrician. I figured it's 12v it couldn't be to complicated. I suppose I was a tad wrong. I can build a space ship guess I shouldn't wire it.
 

dendad

Joined Feb 20, 2016
3,835
Wired as the circuit is drawn will not work BECAUSE the moving part of adpdt switch is the center connection.
Not if you go by the labels on the switch. "C" = Common, "NO" = Normally Open, "NC" = Normally Closed.
Or, at least that is what I expect it to be. The "+" and "-" would be an internal LED.
DPDT_MotorSwitch.png
It was the other way yup in the original post.
 

MisterBill2

Joined Jan 23, 2018
8,793
I have never seen such a switch as the one shown. Can you show the other side? And is there a label as to the brand?
And with an arrangement like that it may momentarily connect the NO and NC terminals on each side as it switches.

So if you have an ohm meter or a continuity checker you could test and see if that is the problem. That is a strange switch indeed.
 

Thread Starter

91five0

Joined Jan 19, 2021
24
I have never seen such a switch as the one shown. Can you show the other side? And is there a label as to the brand?
And with an arrangement like that it may momentarily connect the NO and NC terminals on each side as it switches.

So if you have an ohm meter or a continuity checker you could test and see if that is the problem. That is a strange switch indeed.
its sold and acts like a latching switch, it's a coast brand switch I'm attaching a picture of the other other sidea as well.
 

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MisterBill2

Joined Jan 23, 2018
8,793
OK, then. It is a rotary switch. Once again, I suggest using a continuity check of some kind to verify that there is no momentary short circuit created as it changes positions.
You can do that check by disconnecting the motor and the voltage source, while leaving the wires connected to the switch, and then just check for continuity between the two source wires while moving the switch from one position to the others.
 

Thread Starter

91five0

Joined Jan 19, 2021
24
OK, then. It is a rotary switch. Once again, I suggest using a continuity check of some kind to verify that there is no momentary short circuit created as it changes positions.
You can do that check by disconnecting the motor and the voltage source, while leaving the wires connected to the switch, and then just check for continuity between the two source wires while moving the switch from one position to the others.
I'll give a try. I have to take my DVOM apart and change the fuses. I had a temporary lapse in metal capability yesterday.
 

Tonyr1084

Joined Sep 24, 2015
5,992
I'll give a try. I have to take my DVOM apart and change the fuses. I had a temporary lapse in metal capability yesterday.
When checking continuity or voltage you shouldn't be blowing fuses. If you blow the fuses in the meter you may be connecting the leads incorrectly.

About 10 years ago I got tired of visiting my neighbor to measure the battery voltage on his car. So for Christmas I got him a simple, cheap Radio Shack meter. The first thing he did was to set it up for measuring current and then tested the battery voltage. What he did was a short circuit, which blew the fuse. He told me the meter I gave him didn't work. I replaced the fuse and it worked fine. Until he again used it.

Back in the days when he and I were growing up our fathers often talked about house current incorrectly. The "Current" wasn't 120, the "Voltage" was. As I recall, that was a confusing point in my learning about electronics. It's likely many boys back then learned it wrong. Those days were back in the 60's.

Hook up the leads to your meter and take a snapshot of how you have it and we can tell if you're doing something wrong with your meter. And just so you know, in high school, I blew up a meter when I tested for continuity across a live switch. Live with 120 VAC on it. The teacher was none too happy with that. Point is - we all make mistakes. The task is to learn from them.
 
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