WHICH SWITCH?? Please help choose the correct toggle switch.

[LeftCoast]

Hi all,

Need a switch question answered, but wiring's not my forte. Any help selecting the correct switch and wiring tips would be very appreciated.

I need one push button switch (not a momentary switch; just on-off) that will alternate between two devices (say an 80mm case fan and a 120mm case fan). In other words, when the switch is depressed (it stays pressed), the 80mm fan is on, while the 120 is off. Then, when pressed again (or released), the 80 is turned off while the 120 is turned on. I'm thinking to accomplish this I will need a DPDT (double-pole,double-throw) switch, but obviously being a wiring newb am not certain. Basically, I want one switch to perform the functions of two SPST switches that would always be in opposite positions, if that makes better sense. (Maybe I'd want a SPDT switch for this??????)

Again, any wiring tips/advice you could give would be most appreciated.

Edited for clarification.

[Picard]

First a clarification. Push button and toggle are two different kinds of switches, a switch can't be both push button and toggle. If you are intending to do this for a pc case, this may be a bad idea. In my experience, fans are not hot pluggable, which is what your switch would be doing. Others may have different experience.

[LeftCoast]

Picard,


Items will not be hot swapping; the only time the switch will be used is when the box is off.

Do you know what kind of a push button switch I would need? The more I think about it, the more I'm leaning towards the idea of an SPDT switch. Given your experience, would this be correct? Do you have a link to a basic wiring guide to properly install such a switch, or could you give me the general idea? I know it must be pretty basic, but I don't want to make any rookie mistakes...

Thanks,

No. 1

[rraehal]

You would need a SPDT switch. The pole portion of the descrition tells you how many actuators/butons etc the switch has. The throw portion of the description tells you how many devices can operate.

Most likely when you wire this, you will have three hot pins and a common ground. You would need to hook your fans up so both ground correctly whent he switch is flipped. You would then supply twelve volts to one pin (IN) on the switch that would actuate between your two (OUT) fans.



12V In ----/--< one fan each side

Goround ------ Both fans connected here

[Bovon]

Hmmm, can I express my thoughts concerning toggle vs push-button switches without stepping on too many toes?

Toggle:

tog·gle (t¼g“…l) n. 1. A pin, rod, or crosspiece fitted or inserted into a loop in a rope, chain, or strap to prevent slipping, to tighten, or to hold an attached object. 2. A device or an apparatus with a toggle joint. --tog·gle v. tog·gled, tog·gling, tog·gles. --tr. 1. To furnish or fasten with a toggle. --intr. To alternate between two or more circuit configurations, usually by the operation of a single switch.

In otherwords, as I see it.. a push button type of switch can also be a toggle switch..as the term "toggle" means to change from one setting to another.

What I would do in this case would be search for a push button type SPDT with maybe a center off... I know those are made in the lever (toggle) type switches, up is for one circuit and down is for another...when in the off position, the lever sticks straight out. I have never seen such in a push button type, but I do not recall ever needing that type either.

On a SPDT switch will be 3 solder (or push on type spade terminals) the center one is usually the switching terminal..where the positive 12 volts will be attached. The negative 12 volts will go directly to the fans...they do not need to be switched. One fan will connect to one of the two remaining terminals, and the other fan will connect to the other terminal...now, all 3 terminals have a wire on them. When the switch is activated, it will place 12 volts on one of the fan circuits and that fan will run. When the switch is activated in the other position, the other fan will run. If you happen to find a switch with an off position, then when in that position, neither fan will run.

[Ol'Tunzafun]

What color would you like?
http://www.rpelectronics.com/Default...Div_40_142.asp

[ukulele]

I have a SPST toggle switch on three extra fans. Bovons suggestion of a two position with center off is the way to go for you. Both sides can be single pole. You only need to switch the hot leg. It works fine for extra cooling when it real hot in the room. Don't forget to put a fuse in series with the hot wire. A 3 amp fuse should give you plenty of protection.

[rraehal]

Originally posted by Ol'Tunzafun
What color would you like?
http://www.rpelectronics.com/Default...Div_40_142.asp

The switches on this page are momentary contact and wouls not work in this application.

[Paco103]

Originally posted by Picard
. . . In my experience, fans are not hot pluggable, which is what your switch would be doing. Others may have different experience.

I have noticed no problem with this, however you would want to watch the current. If you run the switch/fans from a standard supply line (such as from a molex connector) you shouldn't have any issues at all. If you want to run it from fan headers on the motherboard - then definitely make sure you only run one at a time, but I still haven't had problems with this.

Also, another question to think about is if you're planning to run RPM monitoring on these fans? If not, then SPDT would be perfect. If you do want to run RPM monitoring, then you will want a DPDT.

then hook the yellow up to the monitoring header on your motherboard and you can also monitor your rpms of whichever fan is active.

Just keep all the yellow on one pole and all the red on another pole. If you buy a switch it should give you a wiring diagram on the back of the package that tells you what goes where.

[Purplecopter]

I dont know much about the theory behind this, (SPDT etc) maybe someone already covered this and I just didn't understand it. Anyway if you want a free push button switch then find an old desktop with a turbo button, behind that will be a 3 or if you're lucky a 6 pin switch. When depressed current goes in the centre, out the left, when the button is out it goes the other way.

[Bovon]

Originally posted by Purplecopter
I dont know much about the theory behind this, (SPDT etc) maybe someone already covered this and I just didn't understand it.

Nope, don't think the technology for a SPST or SPDT etc. was really gotten into..but, since you brought it up, here is a kind of break down.

SPST means single pole single throw..this is like the on/off switch on your walls that turn a light on and off. Single pole just means there is one contact that is being switched. Single pole means that its either a made circuit (on) or it is not made (off).

SPDT means it has two "on" positions. There will be 3 connections to this switch, one for the incoming circuit that is to be "switched" from one item to another...two different lights maybe..switched one way, and light A burns, switch it the other way and light B burns. If this switch also has an off position, it is still classified as a SPDT with a center off. I think this is the type switch used in houses to control a light from two different entrances to the room i.e., a 3/way switch

DPST is when we have a switch capable of controlling two circuits at a time...there would be probably 4 attach points on the back..a simple way to explain this would be to switch both the black and red wires going to a fan..not necessary of course but it can be done.

A DPDT is when we can switch two completely different circuits at the same time when needed. An example might be to set up an alarm where you will want to turn on a light and lock a door at the same time.

[LeftCoast]

Thanks for the work/suggestions all, as they've given me a lot to digest.

If anyone has something to add, please do; I just didn't want you guys to think I blew off the thread...

[Bovon]

I think you have pretty well been advised about your switch question, and unless you have something else to ask or maybe clarify.. I wouldn't know what to add. If you are still unsure about this switch setup or exactly what to get, tell us and we will try to get you setup like you need.

[LeftCoast]

Originally posted by Bovon
I think you have pretty well been advised about your switch question...

As do I, brother! Again, I appreciate all the help.

I like to keep my mind open to anything else that someone might have to add, as again, I'm out of my scope of knowledge here.

[Ol'Tunzafun]

The switches on this page are momentary contact and wouls not work in this application.

Oops.....good catch rraehal, these might be a little better.

6 amp
http://www.rpelectronics.com/Default...Div_40_140.asp

3 amp mini
http://www.radioshack.com/product.as...Fid=275%2D1555

10 amp
http://www.radioshack.com/product.as...Fid=275%2D1555

5 amp
http://www.jameco.com/webapp/wcs/sto...oductId=116667

I would take an ohm meter or a continuity tester to radio Shack with me. It may be necessary to poke holes in a few plastic bags.