Switch for relay
 

Ok this is my LAST relay question, I PROMISE! I have a SPDT ON-ON mini toggle, and a SPDT toggle switch. Does it matter which one I use? I was going to use the mini but the points are very very tiny, and the wire is rather big. I guess as long as I get enough solder on it shouldn't break. Any ways if someone could explain the differences between the switches, that would be great.

Damn...

I use to be able to explain this.

If you have a switch with two positions, 3 prongs...you can use that.

Ground and Power goto one set of the connectrs while the 3rd leg on the outer side is not connected.

Someone come along and convert this to EE grade speak.

Both have 3 prongs, one is just described as a ON-ON swich. I have no idea if that means anything.

SPDT On-On
If I remember correctly has 2 postions, up and down.

works like this:
Center pole is feed wire ( 12 volts constant)
Outer poles go to what ever you are feeding power to.
Flipping the switch up usually makes connection between the center pole and the lower pole.
Flipping the switch down usually makes connection between the center pole and the upper pole.
thus Single Throw Double Pole
The On-On referes to the fact that no matter what position the switch is in, one set of contacts or the other set will be making contact. There is no true off postion.

If you are useing the switch to turn on one circuit, just connect feed to center pole and what you want turned on to either of the outer poles, The circuit will be on or off depending on what way you have the switch flipped.

Hope this helps
Aardil

SPDT means "Single Pole Double Throw"
That means that there is one set (Single Pole) of contacts that swing each time you throw the switch. A "Double Throw" switch can have two or three positions. The On-On means that this switch has two positions. If you put power into the middle terminal (as Aardil correctly stated) the top terminal will be hot when the switch is down and the bottom terminal will be hot when the switch is up.

If you had a SPDT On-Off-On then your switch would be a three position type where there is a center position with no hot terminal (besides the center).;)

If you needed another row of contacts you could get a DPDT (Double Pole Double Throw). Every pole adds another isolated circuit path...

And then if you really want to complicate things, you can specify momentary (spring returned) and maintained positions at each throw.

Hope this helps.

What really matters is how much current the switch can handle. Make sure that it exceeds the current draw of the pump by a good percentage (50%?): it helps to allow the switch to live longer, as the contacts spark when being turned ON, at the moment when the pump motor draws a high starting current.

The switch is just turning on a solid state relay, right?

The switch will allow me to either bybass the relay, and always have the pump on (filling, bleeding). Or go threw the relay.

Also, the relay only has 4 contacts. 2 for the DC dignal and only 2 for the AC... so would I just be hooking up the LIVE to either of the AC contacts, one coming from the PS and the other going to the pump. Then have the NEUTRAL going directly from the PS to the pump. Then have the switch, switching the LIVE current? Let me know if this sounds right.

The mini toggle is rated for 6 amps 120AC. The other is is 16 amps, I'm assuming 120AC also.

Let's see if we can use the switch on the low voltage side only.

Are you using your ATX power supply to provide the low voltage to turn on the pump relay?

Yes, I will be using 12VDC from my PS to turn the relay on.

But I believe the switch MUST swich the AC line. If by low voltage you mean the DC signal, and I wired the relay up on the DC side then I THINK the switch would just alternate between:
A) when computer is on, pump is on
B) pump is ALWAYS off

I might be wrong though... I'm a newb. Someone clarify please.

That is exactly true -I am just looking for alternatives. We could use a 9V battery to run the thing for testing, etc.

Alternatives for what? I am unsure what you think the problem is.

this will not work: ??
hook up the LIVE from the PS to the switch. Have one line going from the switch to the relay AND another line going from the switch to somewhere between the relay and pump (so it bypases the relay). Then have another live wire going from the relay to the pump (for when the switch is not bypassing relay). Then have the NEUTRAL go straight from the PS to the pump.

Explain your concerns.

You got it right CheeseBall: what you're proposing is a bypass to the relay (and it doesn't matter if it's a regular relay or solid state).

I suggested the same idea some time back, but I'm going for 12v pumps now, so I kinda screwed myself out of that one. :(

If you're not sure how to do it, draft up a diagram, post it, and I'll correct it for you.

I wish I could remember how I have mine wired up...I took a schematic off the internet and modified it and crossed my fingers.

Just connect the switch between the two AC terminals (whether it is an electromagnetic or Solid State relay)
http://users.skynet.be/turbokeu/mypr...mpswitchus.wmf

In PDF format

CD :)

In my own "words" here is what I am planning on:
http://www.angelfire.com/me/lastreso...ay-circuit.JPG

One last question (maybe), where is the best place to tie the bypass coming off the switch to. Should I wire it to the 2 on the relay, or wire it right to the pump, or something else?

Also, should I wire the ground wire from my pump to the grond on my PS, or just screw it into my case?

Thanks for the help as always!

As I said, connect the swith to the AC terminals of the relay.
Easiest way...

The electric part of a pump is completely isolated from the rest of the pump, no need for grounding.
In Belgium 99% of the pumps come without ground wire.

CD :)

Either circuit will work fine (thanks Turbokeu: nice work!).

Sorry that I abandoned you last night. I have had problems with my account since the update and have been unable to post. You know what you need to do -I just wanted to explain...