Wire & connectorsBench electronicsHand tools, works as-is

Pin header and connector

Also called Dupont, Molex, JST, fan header.

The 0.1 in pin headers on a motherboard, fan plugs, and the countless white connectors in appliances. A matching pair salvaged together is a connector. One side, alone, is a puzzle.

If you are new to this category

Wire and plugs are how power and signals move. The insulation is the safety, not the copper. Ethernet cable is fine for small signals and low voltage. It is not a substitute for a power cord. A connector you can unplug is worth more than a wire you have to solder every time.

Match the plug that came with the brick. Center-positive is common and not universal. The drawing on the label is a map: the dot is the center, the ring is the outside.

Center pin and outside sleeve

The drawing on the brick is the polarity. A dot inside a C-shaped ring means the center is positive when the plus sign points at the dot. Measure anyway. The two common hole sizes, 2.1 mm and 2.5 mm, almost fit each other and that is how the center pin gets bent.

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
0.1 in	2.54 mm. PC fans, front panel, Arduino-shaped boards.
Appliance	Often a locking ramp connector in 2.5 mm or something that only looks like 2.54. Do not force a fit.

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

Board interconnects
Fan plugs
A cable you can disconnect next time

Leave this one when

The latch is broken and the cable will fall out in the machine.

Buying a new one is the better idea when

A small kit of 2.54 mm housings. Standardize.

How to tell if this one still works

Mate it. Tug it. Beep each position.

Tools you will want: Crimper if you are re-pinning, Meter.

Where people actually find it

2 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
Desktop PC	Bonus	many	always	Front-panel, USB, fans.
Router or modem	Bonus	1	sometimes	A UART pad group.

Bonus, if you are already in thereDesktop PCmany · always
In this particular machine
0.1 in headers and the matching front-panel leads.
Where to look
Front-panel, USB, fans.
How to get it out
Unplug first. Desolder headers only if you need them.
The condition to expect
Good.
Bonus, if you are already in thereRouter or modem1 · sometimes
In this particular machine
Unlabeled 3.3 V serial, if you already do that kind of work.
Where to look
A UART pad group.
How to get it out
Do not invent a pinout.
The condition to expect
Fine.