Switching & protectionRebuild shelfHand tools, works as-is

Microswitch

Also called snap switch, Omron mouse switch, limit switch, D2FC.

A snap-action switch with a real mechanical life. The one in a mouse is the best cheap switch most people will ever hold. Door interlocks in microwaves are the heavy mains-rated cousins.

If you are new to this category

A switch opens or closes a circuit. Some switches are for your finger. Some open when they get too hot and stay open. Those do not reset. A relay is a switch that a small current turns on so it can control a larger current. Use the rating printed on the part.

Click it and listen. Then use a meter on continuity, which beeps when the contacts touch. Do not guess that a small switch can run a motor.

The three legs of a snap switch

Common is the moving contact. NO means normally open: that leg connects only while you press. NC means normally closed: that leg is connected until you press. Click the button while the meter is on continuity and write down which beep matches which leg.

Mains voltage. Line voltage, and the DC bus just after the rectifier, both kill. A disconnected cord is not a discharged supply.

Specification. The right-hand column is what is typical. The label on the part in your hand wins if they disagree.
What to look for	Usual figure
Mouse	Omron D2FC-F-7N and the 10M/20M/50M grades, or Kailh/TTC clones. Logic current, not a motor switch.
Appliance	Often 5–16 A at 125/250 VAC. The rating is stamped on the side. Believe the stamp, not the size.
Pins	Common, NO, NC. Click it while you beep it so you know which is which.

Volts are electrical pressure, amps are how much current is flowing, and ohms are how hard the part resists that flow. A higher voltage than the part was built for is how salvage parts die on the bench. If a cell in the table says “read the stamp”, that stamp is the whole specification.

What people actually use it for

Limits
Operator buttons
Replacing a dead mouse switch of the same footprint
Detecting a door

Leave this one when

The button feels mushy or it double-clicks on a slow press. That is the failure mode.

Buying a new one is the better idea when

A rated industrial limit switch, once a human safety circuit depends on it.

How to tell if this one still works

Continuity through the click. A good one is silent in the meter and sharp in the finger.

Tools you will want: Meter, Soldering iron for mouse switches.

Words on this page

Short meanings, so the rest of the entry is readable if you are not already doing this every weekend.

mains: Ordinary household wall power. It can kill. Unplug before you open anything that used it, and do not experiment on live wiring.
continuity: A meter mode that beeps when two points are connected. It is how you map a switch: beep, then click, then see if the beep changes.

Where people actually find it

8 notes, most useful first. “Leave it” means the part is in that machine and you should not take it: it is dangerous, worn out, or only useful if you already know that exact repair.

Harvest at a glance
From	Call	How many	How often	Where it sits
Optical mouse	Prize	2–5	always	Under the main buttons and the side buttons.
Microwave oven	Prize	3	always	Door latch.
Laser printer	Worth it	several	usually	Doors and trays.
Dishwasher	Worth it	1	usually	Door.
Garage door opener	Worth it	2	usually	Limits.
Cordless vacuum	Bonus	1	usually	Trigger.
Game controller	Bonus	2	sometimes	Shoulder buttons, on better pads.
E-scooter or hoverboard	Bonus	2	usually	Brake levers.

Prize — take this firstOptical mouse2–5 · always
In this particular machine
Omron D2FC series or a clone. Logic current, not a motor switch.
Where to look
Under the main buttons and the side buttons.
How to get it out
Desolder. Note the feel. Mushy ones are the reason the mouse was binned.
The condition to expect
Sharp ones are excellent. Double-clicking ones are scrap.
Prize — take this firstMicrowave oven3 · always
In this particular machine
Mains-rated interlocks. One is a monitor switch arranged to blow the fuse if the door switches are defeated.
Where to look
Door latch.
How to get it out
Label each wire before you disconnect. Do not reinstall the oven without them.
The condition to expect
Good.
Worth pullingLaser printerseveral · usually
In this particular machine
Interlock and paper-present switches.
Where to look
Doors and trays.
How to get it out
Map them before you cut the loom.
The condition to expect
Good.
Worth pullingDishwasher1 · usually
In this particular machine
Interlock.
Where to look
Door.
How to get it out
Map it.
The condition to expect
Good.
Worth pullingGarage door opener2 · usually
In this particular machine
End of travel.
Where to look
Limits.
How to get it out
Map them.
The condition to expect
Good.
Bonus, if you are already in thereCordless vacuum1 · usually
In this particular machine
Logic level into the controller.
Where to look
Trigger.
How to get it out
Map it.
The condition to expect
Good.
Bonus, if you are already in thereGame controller2 · sometimes
In this particular machine
Real switches.
Where to look
Shoulder buttons, on better pads.
How to get it out
Desolder.
The condition to expect
Good.
Bonus, if you are already in thereE-scooter or hoverboard2 · usually
In this particular machine
Cutoff switches.
Where to look
Brake levers.
How to get it out
Map them.
The condition to expect
Good.