Hey there, fellow makers, engineers, and anyone who’s ever fumbled with a clicky button to turn something on or off—let’s talk push button switches. If you’re like me, you probably take these little workhorses for granted until you need one that actually works the way you want it. As a push button switch supplier, I’ve seen every config under the sun, and let’s be real: picking the wrong one turns a simple project or fix into a headache. Today, I’m breaking down the main contact configurations you need to know—no stuffy jargon, just real talk from someone who sells these things for a living. Push Button Switch
First off, let’s keep this simple: contact configs are just how the switch connects (or disconnects) power when you press it. Think of them as the switch’s “job description.” You’ve got basic ones for small projects and wild ones for industrial stuff, and if you mix ’em up, your whole setup crashes. I’ve seen it happen—last quarter, a guy came to me panicking because he bought a “momentary” switch that stayed locked on, and he needed it for his arcade machine’s joystick trigger. Oops. Let’s start with the basics so you don’t make that mistake.
1. Normally Open (NO) – The Click That Happens When You Push
This is the most common one, right? If you press the button, a connection gets made. Let’s visualize it: inside the switch, there’s a metal arm (contact) that’s not touching the other terminal at rest. Push the button, and the arm bends to touch the terminal—power flows. When you let go, it springs back, and the connection breaks.
What’s NO good for? Literally everything that needs a temporary trigger. Arcade buttons, doorbells, car window locks, even the start button on your microwave. Wait, hold on—wait a sec, some people mix this up with momentary, but NO is the contact type, momentary is how long the press lasts. Oh, right, I should clarify that quick: contact config is about the circuit’s state, not how long you hold the button. Momentary is when it snaps back, latching is when it stays—those are switch functions, not configs, but they go hand in hand.
As a supplier, I stock NO switches more than any other. They’re cheap, versatile, and 9 out of 10 projects ask for ’em. Last week, a teacher bought 50 for her middle school robotics class—each one is for a robot’s “fire” button on the competition bot. Perfect for that, since you press it once to trigger, release and it stops. No surprise there.
2. Normally Closed (NC) – The Always On (Until You Push)
Total flip of NO. At rest, the circuit is connected. Press the button, and the contact arm pulls away, breaking the circuit. So power stops flowing when you push, resumes when you let go.
What’s NC used for? Safety stuff, mostly. Like the emergency stop (E-stop) buttons on power tools or factory machinery. If someone’s hand gets caught, they yank the E-stop (wait, E-stops are actually latching NC, but I’ll get to that), but even momentary NC works for things like door sensors. Wait, think of a fridge door: when it’s closed, the door’s push button is pressed, so the light circuit is broken. Open the door, the button pops out—NC, so the light turns on. Yeah, that’s exactly NC.
I remember selling NC switches to a guy who built custom garage door openers. His old one used a NO button, but if the power cut out, he couldn’t open it manually. The NC setup kept the door closed (powered) by default, so if the remote died, he could pry the button to open it without fighting it. Smart guy, knew his configs.
3. Single-Pole Single-Throw (SPST) – NO or NC, Basic AF
Okay, now we’re adding “pole” and “throw” to the mix—don’t run away, this is easy. A “pole” is how many separate circuits the switch controls. A “throw” is how many positions each pole can switch to.
SPST is one pole, one throw. So it’s just a simple on/off switch. That’s exactly NO or NC—no extra contacts. No fancy switching, just one circuit, two states. It’s the entry-level config. If you’ve got a project that only needs turning one thing on or off, SPST is your boy.
Wait, why is this a separate category? Because a lot of new builders mix up contact type (NO/NC) with pole/throw. SPST is the simplest pole/throw combo for NO or NC. I stock SPST NO and SPST NC, and they’re super affordable—great for prototypes or small jobs where you don’t need extra circuits.
4. Single-Pole Double-Throw (SPDT) – The Switch That Flips, Not Just Closes
Here’s where it gets fun. SPDT is one pole, two throws. So it can connect one common terminal to two different terminals. At rest, it’s connected to, say, Terminal 1. Press the button, it flips to Terminal 2. No breaking the circuit completely—just switching between two paths.
What’s SPDT for? Anything that needs to pick between two options. Like a light switch that lets you choose between two bulbs, or a speaker that switches between two audio sources. Wait, think of a lamp with three settings: off, low, high. Wait, no, that might be double-pole, but for a simple toggle between two circuits, SPDT is perfect.
I recently sold SPDT push buttons to a streamer who built a custom control board for his setup. One button flipped between his gaming PC’s audio, his mic line, and his background music—wait, no, actually two audio sources for his headset and speakers. Exactly, SPDT lets him switch without cutting power, so the audio doesn’t glitch mid-press. That’s the magic of it. No sputtering, just a clean flip.
5. Double-Pole Single-Throw (DPST) – Two Circuits, Same On/Off
DPST is two poles, one throw. So it controls two separate circuits at the same time, both on or both off. Why would you need that? If you’re switching something that needs two power lines—like a 240V outlet for an air compressor, or a motor that needs both hot wires. If you used two SPST switches, they might get misaligned, but DPST hits both circuits at once.
Wait, but can DPST be NO or NC? Yep. Usually it’s NO for big power draws. I don’t sell as many DPST for consumer stuff—mostly industrial. Last month, a factory maintenance guy bought a bunch to replace old push buttons on their conveyor belt system. They needed to cut both power lines when the E-stop was hit, so DPST was the only config that would work without risking half-power.
6. Double-Pole Double-Throw (DPDT) – The Swiss Army Knife of Switches
Now we’re at DPDT: two poles, two throws. That means you can switch two separate circuits, each between two paths. It’s like two SPDT switches in one. This is the most versatile config, used for all sorts of tricky setups—like reversing a motor’s polarity (think of power windows rolling up or down), or switching audio between four different sources.
Wait, I actually built a small pedal for my guitar a while back that used a DPDT push button. It toggled between clean and distorted signals, flipping two wires at once so the tone didn’t crackle. Worked like a charm. As a supplier, DPDT is my go-to for anyone doing more than simple on/off. It’s a bit pricier, but worth it for the flexibility.
Bonus: Latching vs. Momentary – Wait, No, Those Are Functions, Not Configs
I said I’d clarify this earlier, but it’s important because people mix this up. Latching means the button stays in the pressed state when you let go—you press it once, it stays on, press again, it switches off. Momentary means it springs back when you let go. Those are how the button behaves, not the contact config. You can have latching NO, momentary NC, etc. For example, the E-stops I mentioned earlier are latching NC—they break the circuit when pressed, and stay broken until you twist them to reset. That’s a combo of function and config, not a separate config.
Real Talk From a Supplier: How to Pick the Right One
Let’s cut to the chase—when you’re ordering push buttons, don’t just say “I need a button.” Ask yourself two things:
- Do you need to switch one circuit or multiple? (That’s pole count: 1 or 2, mostly.)
- Do you need to connect one thing, switch between two, or break the circuit entirely? (That’s throw count, plus NO/NC.)
- Do you need it to stay pressed or snap back? (That’s momentary vs. latching.)
I’ve had customers come in with projects that call for a DPDT momentary NC, and they try to order an SPST NO because they don’t know the difference. Don’t do that. It’s easy to mix up, but asking those three questions saves you from returning a bunch of switches (and wasting my time, let’s be real—we both hate returns).
For example: If you’re building a doorbell? SPST NO momentary. Simple. If you’re building an E-stop for a woodworking saw? DPST NC latching. If you’re switching between two gaming consoles on your TV? SPDT momentary. If you’re flipping a motor forward and reverse? DPDT latching.
Final Note: Reach Out If You Need Help
Look, I’ve been in this game long enough to know that even the most seasoned engineers mix up a config every now and then. I stock all these contact configurations in bulk for industrial orders, and small quantities for hobbyists and makers too—no minimums for one-off projects, no weird hoops to jump through. Whether you’re building a robot, a custom arcade cabinet, or fixing a factory machine, I can help you pick the right push button switch that doesn’t let you down.
Connector If you’ve got questions about specs, pricing, or even just need to bounce an idea off someone who actually knows these switches inside and out, hit me up. Let’s get your project rolling (or fixed) the right way—no more wrong config headaches.
References
- "Push Button Switch Fundamentals", Electrical Technology, 2022.
- "Switch Contact Configurations Explained", All About Circuits, 2023.
- "Industrial Push Button Selection Guide", Automation Direct, 2021.
Zhejiang Aokai Electric Co., Ltd.
Zhejiang Aokai Electric Co., Ltd. is your best source for the high quality push button switch with CE certification. We have been one of the largest push button switch manufacturers and suppliers in China since our establishment in 2008. Welcome to contact our factory for the products.
Address: No.166 Xiangbai Road, Huxi Industrial, Yueqing, China.
E-mail: akcontactor@aokai.com
WebSite: https://www.ak-contactor.com/
