# Need help finding a solution - switch / Help for a noob - relays

Discussion in 'General Electronics Discussion' started by alon, Jun 7, 2011.

1. ### alon

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0
Jun 7, 2011
Hi guys,

I'm in need of a specific switch that will allow the following:

- The switch needs to have 3 contacts (legs)
- Switch OFF -> no contact between any of the legs
- Switch ON -> contact between all of the 3 legs

I've looked everywhere, but I couldn't find anything that fits.

Can you advise on a switch that will fit?

Also,
I was wondering, if I take a simple 3 leg on/off rocker switch and connect 2 of the leg with a diode, will it solve it?

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2. ### davennModerator

13,671
1,892
Sep 5, 2009
hi there welcome to the forum

I think you need to tell us all more about what you are actually trying to achieve
I can only assume that you dont really want to short circuit the + and the - of a power supply as shown in your diagrams ? as that would result in a blown power supply

cheers
Dave

3. ### BobK

7,682
1,686
Jan 5, 2010
You could use a 3PST switch to achieve this:

o----/ o-----+
|
o----/ o-----+
|
o----/ o-----+

Connect your three wires to one side of the 3 switches, and connect the other side of the three swiched all together.

Bob

Last edited: Jun 9, 2011
4. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,418
2,788
Jan 21, 2010
You could also use a DPST switch. Just replace one of the switch contacts shown above with a link. DPST switches are far more common too.

5. ### alon

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0
Jun 7, 2011
Help for a noob - relays

Hi guys,

I have a simple circut,
3 negatives (with no contact between them)
1 positive (12V)

I need to be able to conect the positive to the 3 negatives using a simple on/off switch.
I assume the best way to do this is using a relay.

- Am I right?
- What kind/type of relay can I use?
- How should the circut look?

Alon

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6. ### shrtrnd

3,773
493
Jan 15, 2010
This is probably an engineering question. I'm a tech.
I think in terms of physical connection. I don't understand from the drawing, what it
is you're trying to do.
If this is theory, some engineer can probably figure-out what the drawing means.
that you're trying to do.

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Jul 31, 2009