Components: Switches

Okey dokey, we all know what a switch is; I mean we all have them in our house, right? You flick it when your lights are off and they suddenly turn on. Now what you may not know is how stinking complicated they can be and how stinking large the variety of switches is. I'm about to unleash a whole new world on you. 

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Look at that big 'ol switch. Looks simple, right? That's because it is. When it's off, you flip it to turn it on. Well, how does it work? MAGIC!! No... it too is pretty simple. There are two main parts to this rocker switch: the actuator and a set of contacts. The actuator... well, actuates and the two contacts sit next to each like a 2x4 that got a few inches cut out the middle. When the switch is "off", the contacts are "open", meaning they're not connected. When the switch is in the "on" position, the actuator connects the two contacts, "closing" them so a current is able to flow through from one to the other.

Now, it gets more complicated. There are many more kinds out there. What if you want to switch two currents at the same time? What if you want one position to close one connection and the other close another? Man that was a mouthful. I bet you had to read it more than once! Anyway... we have a system for this ordeal. A switch that would simply have an off position and one other that would close a connection would be a SPST switch, or a single pole, single throw switch.

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Take a look at this here knife switch. This is a SPST switch. Do you see the "knife?" Well, that's the pole. There's only one pole, or a single pole. This is where the SP in the abbreviation SPST comes from. There's also only one spot the knife slices into. This spot it called a throw; which explains where the ST comes from. Now... why is that connection called a throw? Well, technically in engineer language, when you flip a switch, you're supposed to say throw instead of switch. Why? No clue. Personally, I think it sounds goofy. "Honey, it's dark in here. Would you find throwing the light switch?" Funky. Anyway, that's why this type of switch is called a SPST switch.

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Now this here is a DPDT switch. You see these switches bolted to crazy scientist's lab walls. Now... why is it called a DPDT switch? Let's start with the poles. If you look very closely, you'll see that there are two knives! Bravo, you got it. What about the DT portion of the name? There are two sets of contacts, so it's a double throw. Simple enough! Now, what do you think it would look like if one knife went bye-bye? Well, it'd be a SPDT switch because there are two connections and one knife. What if it had four knives? Then it'd be a 4PDT switch.








Ok. Now, the thing is, you aren't limited to just one or two poles. If you need a switch that makes 1000 different connections, congrats. It's a 1000P whatever throw switch. You are however limited to the number of throws with this specific type of switch. Now there are switches out there that have multiple throws, like the rotary switch, but with the flip switches you'll probably only see a ST or DT switch. So since there are multiple different states each switch can be in, you know, on or off, how would we indicate that? Well, the only factor that affects the number of states is the throws. If you have a SPST switch, there's the off position and the on position so that leads it to be an ON-OFF switch. If you have a switch with two poles, it'd be an ON-ON position. I know I'm stating the obvious here, but you need to know this. Why? Well some DP switches will actually have a middle position in-between the two on positions called the OFF position. This sucker is a life saver because without it, a DP switch would always be on. Always, no matter what. When the switch is in the off position, no current can flow through, which is brilliant. So, a DP switch with an off position would be an ON-OFF-ON. There's an actual reason for this. Push button switches can be momentary or not and they specify this by using the on/off system. If a momentary button only turns on if you hold it down because if you release it, it turns back off. How would you specify the secondary position is monetary? OFF-(ON). The parenthesis tell you the on position is momentary. Man... aren't switches fun? I made all this sound much more complicated than it really is but once it clicks in your head, it really seems simple.

Now, if you'd like to see a nice, wide variety of switches and buttons out there, click here to check them out!