Power & batteryYou will see this often
Wall adapter
Also called wall wart, power brick, USB charger, laptop brick.
The correct salvage is the whole sealed supply, labeled with the voltage you measured. Opening one to steal a controller throws away a working supply.
A donor is the dead machine. The parts below are what is still worth removing from it. “Leave it” is a part that is physically in there and should stay in there: too dangerous, too worn, or only useful as part of a repair you are not doing.
Left: a brick. The label is your spec, and the plastic is the safety barrier. Right: a board taken out of a lamp or a charger. Unless you have checked that the output is isolated from the prongs, do not let it touch a project you will handle while it is plugged in.
Why it is in the trash while the parts are not
The device it fed is gone. The brick is usually fine. Laptop bricks die from a cracked cord at the grommet.
Before you open it
Do this while it is still unplugged, cool, and not leaking. You rarely should. Mains is on the primary side if you do crack the case.
Where the dead machine usually is
- Junk drawer and cable box — In the house
- Home office — In the house
- Office cleanout — Commercial
The drawer. Label them the day you identify them.
How it comes apart
Ultrasonic weld. If you must look inside, it is a destructive cut. Prefer the label and the meter.
Tools: Meter.
Words on this page
- mains
- Ordinary household wall power. It can kill. Unplug before you open anything that used it, and do not experiment on live wiring.
What to take
The table is the short version. The notes under it describe that part inside this machine, not only the general description.
| Part | Call | How many | How often | Where to look |
|---|---|---|---|---|
| Switch-mode wall supply | Prize | 1 | always | The whole brick. |
| Barrel jack | Worth pulling | 1 | usually | The plug. |
| USB cable | Worth pulling | 1 | sometimes | Fixed USB chargers. |
| Iron transformer | Worth pulling | 1 | sometimes | Heavy old adapters. |
| Ferrite core | Bonus | 1 | usually | On the cord. |
| Electrolytic capacitor | Leave it | 1 | sometimes | Inside, if you cut it open. |
Prize
Voltage and current on the label. USB-PD is negotiated, not fixed.
The whole brick.
Measure unloaded and with a load. Confirm isolation once.
Cord damage is the laptop-brick failure.
Worth pulling
Measure the bore. Confirm polarity.
The plug.
Keep it on the brick.
Bent center pins are scrap.
Often power-only.
Fixed USB chargers.
Load-test it.
Fine.
Iron, 50/60 Hz, isolated.
Heavy old adapters.
The weight is the tell.
Good.
Bonus
A clip-on or molded bead.
On the cord.
Slide it off.
Good.
Leave it
The output cap.
Inside, if you cut it open.
Not worth destroying the brick.
Leave it.