A while ago I stocked up on jumper wires from Sparkfun and recently found while connecting an Arduino clone to a Raspberry Pi that the single straight header on both ends was not what was needed. Unlike the male breakaway headers, these female JST RE wire headers do not split up.

To solve this you need some donor wires. These can be found at your local e-waste recycler in old desktop PCs. You will commonly find a long ribbon cable running from the front panel LEDs to the motherboard. The motherboard end will have an assortment of JST RE headers in various sizes. If your recycle dude is in a good mood, this will be free. My guy even smashed a PC open for me and lent me a screwdriver. If you make a donation at the same time, it probably helps. Grab a bundle.

When you get them home, compare the tips to the cable you want to adapt. The ones pictured below match the Sparkfun wires.

Pop the wires out of the headers in the cables with the tip of one of your Arduino breadboard jumper wires. The trick is to push the wire in to expose a small gap between the metal tang and the plastic tang. Insert the point of your breadboard wire behind the plastic tang, and you should be able to slide the metal tip of the jumper wire out. Don’t pull the plastic tang back, and don’t bend anything on the metal tip or force anything.

This is tiny stuff, so if your eyes are going, you’ll want the magnifier.

Now you can pop any cable in any hole in any header and make any combination you need.

Here’s the one I made recently.