I am building a fairly simple electricity project. It requires a dpdt toggle switch. I bought one at an electronics surplus store. It reads 125 VAC on the outside but my source is 3 VDC. Will this work? Any ideas on how to wire it? I am a newbie to this type of thing.
Yes, it will work fine.
ETA: How to wire it? It depends on what you want to do… DPDT is often used to reverse the direction of DC current flow, like to a motor. Is this what you are doing?
It will work. 125VAC is the max rating.
Think of it as a pair of SPDT switches together. Like the one Dr Frankenstein used to animate his creature.
Switches have two ratings. The voltage rating will be the maximum voltage before you start getting arcing across the contacts. You don’t want to exceed that voltage. So in your case you don’t want to exceed 125 VAC. 3 VDC is a lot less than that, so no problem.
There will also be a max current rating, which you won’t want to exceed or the contacts and conductors inside the switch could overheat and the switch could melt. You don’t mention the current rating, but really, since you’re just dealing with small DC voltages, I wouldn’t expect the current to be high enough to damage the switch.
As for how to hook it up, well, that depends on what you are trying to do. Can you post a schematic? Basically, there are six terminals on the bottom of the switch. When the switch is turned one way, the center termonal on the left will be connected electrically to the bottom terminal on the left, and the center terminal on the right will be connected to the bottom terminal on the right. Flip the switch, and the center terminal on the left will disconnect from the bottom terminal on the left and will instead connect to the top terminal on the left, and the center terminal on the right will disconnect from the bottom terminal on the right and will connect instead to the top terminal on the right.
If you are having trouble understanding it from my brief description, this pdf file has a better description with pictures:
http://www.musicfromouterspace.com/analogsynth_new/ELECTRONICS/pdf/switches_demystified_assembly.pdf
VAC vs. VDC makes a difference as well. Some switches depend on the zero crossing of the AC signal to make a clean break of contact. Under the right conditions, the same voltage at DC could sustain an arc.
Obviously not a problem for 3 VDC, but it’s something to keep in mind when doing other replacements.
That schematic really helps. Thanks.
I think my switch is broken. Pin 2 is connected to pin 6 no matter what position the switch is in and none of the other pins connect in any way. It seems that a check on the switch is pretty straight forward if I follow the schematic in the link above. Am I correct?
Yeah, based on your description I’d say it’s toast.
Is this a power application, or signal-level application? What’s the current?
Just an IMO, but I’ve never been a fan of slide switches. Most do not have an internal snap spring mechanism, which means the contact open & closure speeds are determined by the speed your finger moves the switch. Moving the switch too slowly can cause all kinds of problems (excessive bounce, prolonged arcing, etc.). Furthermore, the switch is able to reside between the two states for an indefinite period of time. You should always use a switch that has a snap spring mechanism, which means the contact open & closure speeds are independent of the speed your finger moves the switch, and only two stable states are possible.
Oops, ignore the second paragraph. The OP says he’s using a toggle switch, which usually have a snap spring mechanism. :smack: