On a SPST switch - why the 3 pins?

Model Railroader Electronics and DCC
1

This really is a simple question to the right person. I bought some mini toggle switches ( spst / spdt ), on/off. The part that throws me off is, it is 3 pins. Does that mean that the end pin, I guess either end, is a ground? My intent is to isolate a spur track with insulated rail connecters and then somewhere within that spur put power to the track. Do I take one leg of the connection, either N or S and run it to the spst switch? Connect to the end pin and the middle pin?

2

Are you sure it is SPST? My other thought it is there might be a light in that lights up when off or on.

3

Sounds more like a SPDT toggle, perhaps with a center off position? Anyway, grab your ohm meter and see which of the pins are linked with the toggle thrown in each direction. It could be that one of the pins is not connected to anything and simply there to aid in attachment to a board?

4

Three pins is SPDT. Single pole, doublt throw. Menas it clsoes circuits in two positions. The center pin gets connected to one of the outside positions depending on the direction you move the handle. No worries, they can be used like SPST, just ignore one end terminal and use the center plus the other end.

–Randy

5

And remember that a double throw toggle switch connects the centre pin to the end pin that is opposite to the direction the handle is moved.

6

Thanks so much for all the feed back. I know the best way to connect switch to wire is to solder, so that’s what I will try and do. Although it will take a connector.

7

Help yourself and get an inexpensive meter that will measure resistance (OHMS scales) and DC voltage both in several ranges the DC should have at least an 0- 20 volt range and several others .DC current in a usable range is not always provided in less expensive meters not totally necessary. There may be an AC scale but dont go probing household receptacles unless you know what you are doing . With a meter like that you could answer some of your questions. I am thinking of the meters at the bargain tool company or good old Radio ----- these wont break the bank and if you damage or break it buy another.