MotionBench electronicsUnplug and unscrew
Blower (centrifugal fan)
Also called squirrel cage, laptop fan, centrifugal blower.
Moves air against more pressure than an axial fan of the same size. Laptop blowers, projector fans, some vacuum heads, hair-dryer style impellers.
If you are new to this category
These parts spin, push, or pump. A motor is a machine that turns electricity into turning. Some start turning as soon as you connect a battery. Others look identical and will not move until a small circuit tells them which coil to power next. The label, or the number of wires, is how you tell them apart.
Count the thick wires before you apply power. Two wires usually mean a brushed motor that can run from a battery. Three thick wires usually mean a brushless motor. Keep the board that came with a brushless motor.
This is usually a brushless motor. Connecting a battery across two of the wires only makes it twitch, and holding it there heats the winding. Keep the small plug as well. Those thin wires are often the sensors that tell the board where the shaft is.
Mains voltage. Line voltage, and the DC bus just after the rectifier, both kill. A disconnected cord is not a discharged supply.
| What to look for | Usual figure |
|---|---|
| Laptop | 5 V or 12 V BLDC on a small board, often with a PWM or a simple on wire |
| Appliance | Can be mains shaded-pole. Read it. |
| Direction | The scroll housing only works one way. Keep the housing. |
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
- Cooling a dense box
- A small wind source for a burner or a fume hood
Leave this one when
The impeller rubs the housing. Foil and tape repairs last a day.
Buying a new one is the better idea when
A catalog blower when the laptop one is a weird shape you cannot mount.
How to tell if this one still works
Rated voltage, housing on. Rubbing is a fail even if it spins.
Step-by-step on the bench: Power a salvaged BLDC without magicTools you will want: Meter.
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.
- BLDC
- Short for brushless DC motor. See brushless. The 'DC' does not mean you can hook it to a battery with two wires.
- PWM
- A rapid on-off signal used to control speed or brightness. A four-wire computer fan uses it on the fourth wire.
Where people actually find it
1 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.
| From | Call | How many | How often | Where it sits |
|---|---|---|---|---|
| Laptop | Worth it | 1 | usually | On the heat-pipe assembly. |
- In this particular machine
- A small centrifugal BLDC, 5 V or 12 V, often PWM.
- Where to look
- On the heat-pipe assembly.
- How to get it out
- Unplug the fan before you lift the heatsink.
- The condition to expect
- Good if it was not the reason the laptop was loud.