Wiring a switch question

[hembramacho]

Had a go at fitting my new thermometer/clock/voltmeter today, taking the 12v feed from an existing wire coming directly from my LB. I wanted to fit a switch so I could switch the unit on/off when I wanted to, so am using one of these:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... K:MEWAX:IT

The switch has 3 terminals, marked +, A and earth.

The feed has a + wire and a - wire, so I've left the + as it is and am taking the - wire into the switch terminal marked + and bringing it out of the A terminal. The switch works fine, but I would really like the LED on the switch to light up when the switch is on.
This is where I'm confused.
I'm putting a seperate earth wire into the 3rd terminal (marked earth) with the assumption that this will make the LED work. It does, but the wrong way round! As in, the LED lights when the switch is off, and goes off when the switch is on.

Any thoughts as to what I'm doing wrong. I've used this kind of switch before when I wired up an LED strip for the side step and followed the same procedure, so am kind of baffled.

Cheers

Andrew

[g8dhe]

I would have expected that the L/B +ve would go to the +ve contact of the switch, the A contact would go to the +ve of the meter and finally the switch Earth, L/B -ve and the meter -ve would go to the chassis/earth. But these things don't always obey normal marking standards!

[hembramacho]

I would have expected that the L/B +ve would go to the +ve contact of the switch, the A contact would go to the +ve of the meter and finally the switch Earth, L/B -ve and the meter -ve would go to the chassis/earth. But these things don't always obey normal marking standards!

Cheers Geoff.
I was going off your previous advice with the idea that positive is left alone and negative is the one you break with the switch:

http://www.igmaynard.co.uk/bongo/forum/ ... =3&t=37607

Obviously that isn't always the case. Should I try and break the positive with the switch instead of the negative, using + and A, and then just earth the earth?

Thanks as usual.

Andrew

[daveblueozzie]

You need to wire from the positive not the negative for it to work the way you want. basically you have it wired in reverse.

[hembramacho]

You need to wire from the positive not the negative for it to work the way you want. basically you have it wired in reverse.

Cheers Dave - will try that tomorrow.

Happy new year..

Andrew

[daveblueozzie]

Here is a diagram of how to wire the switch (three terminals)

[haydn callow]

Yep !! don't forget to put the fuse in the circuit.

[Diplomat]

Yep !! don't forget to put the fuse in the circuit.

Definitely need a fuse if the red and black ends are joined together!

Frank

[hembramacho]

Thanks for that - very helpful diagram DBO.

Have already got an in-line fuse in the circuit, so will have another go today and report back.

Cheers

Andrew

[g8dhe]

I was going off your previous advice with the idea that positive is left alone and negative is the one you break with the switch:

http://www.igmaynard.co.uk/bongo/forum/ ... =3&t=37607

Obviously that isn't always the case. Should I try and break the positive with the switch instead of the negative, using + and A, and then just earth the earth?

Yup its not the same situation here as you want the LED to light up, so you have to have a +ve supply going to the switch and also the earth to provide power to the LED the A lead is just the change over contact which moves between +ve and Earth connections and it also has the LED built into it. The pictures above should do the trick.

[hembramacho]

Sorted - all working as intended, so massive thanks for all the input.

This is what I was trying to switch on and off



Cheers

Andrew