ETextile Multimeter Pin Probe

Pin Probe as published in the eTextile Swatchbook 2017

The Pin Probe is a test lead to connect between a multimeter and conductive fabric or thread. The probe consists of a pin to make temporary but firm contact with textile materials without harming them. A soft and flexible textile cable then connects the probe to a banana plug to connect to a multimeter.

The Pin Probe is designed to aid processes of textile electronic making, allowing to pin the probe to the textile material and have both hands free for the crafting routine. Directly while stitching the connection, the multimeter provides continuous information about its current electrical value. The immediate feedback allows instant action, facilitating an aesthetic-driven workflow to reach precise electronic results.

This instructable shows the making of a Multimeter Pin Probe. But you can also make a prototyping cord with pins at both ends, if that is what you rather need, or with a clip, or any other connecter at the other end.

(This is a copy of the instructions on http://www.ireneposch.net/pinprobe-diy/, 2017)

• 4 mm banana plug
• 9 mm shrink tube (3:1 shrink ratio is ideal)
• paracord (or an other flexible cord that lets you puush through a thread in the middle)
• conductive thread (I am using a 7×5 copper thread from Karl Grimm. if you have a thinner or less conductive material bread it together or use several strands to increase the conductivity. you can also use a flexible cable)
• 3D printed handle (Shapelock could also be used to form a handle if no 3D printer is available)
• pin (stainless steel, or other highly conductive material, should not have a coating)

• scissors, cutter knife, glue gun, lighter, screw driver, multimeter, solder iron, solder, needle
• 3D printer if you want to print the handle (download below)

• cut app. 1 meter off the paracord (you can adapt the length if you want your probe cord to be longer or shorter. To connect to the multimeter, 1 meter is a good starting point.)
• pull out the inner nylon cord

• thread a (stump) needle with the conductive thread (or cable) and push it through lengthwise through the paracord until it comes out at the other end
• when pushed through, remove the needle and make a knot
• spread the paracord coating evenly across the conductive core
• be carful the conductive thread does not slip through

• make a knot at the end

• put some solder on the knot (this is optional, but I it makes it easier to establish good contact)
• push the knot into the banana plug
• fix it, screwing the screw in
• try pulling on it to make sure it is fixed
• slide the end of the cord coating into the banana plug as well
• cut of the fraying ends of the conductive thread

• measure the resistance between the connector part of the banana plug and the conductive thread at the other end of the cord. the resistance should be below 1 Ohm but depends on what material you are using
• if all looks good, use the glue gun to fix the conductive thread and cord into the banana plug
• cut a 3 cm piece from the shrink tube
• cover the banana plug with the shrink tube and heat it so the tube shrinks around the banana plug and the first few millimeters of the cord
• let it hang verticallly so the glue hardens with the cord in the middle. this side of the probe is now finished

• cut the conductive thread on the other side leaving it 3 cm longer than the covering cord
• pull back the cord a bit and make a knot where the conductive thread exits the cord
• push the pin through the knot
• (optional: fix the knot with a drop of solder, make sure the drop is not too high. if you are using a cable, solder the cable to the needle)
• cut off any fraying ends of the cord (you can burn them carefully with a lighter)
• measure the resistance between the banana plug and the pin. the resistance should not be higher than what you measured last time
• cut off the rest of the conductive thread, or cable

• place the needle in the bottom part of the handle (the bigger one) so that the connection between the needle and the cord sits in the middle and the needle is pushed through the small opening in the handle.
• you can use some glue to close the handle with the 3D printed top (be careful not to use too much glue)
• quickly place the top before the glue dries
• hold the glued handle together for a little while until the glue is dry/hard

• measure the resistance between the two ends of the probe
• the resistance should not be higher than what you measured last time, ideally it is lower, as everything is closely glued together now
• you can do the measuring in plugging the Pin Probe into the multimeter and contact the pin with the other probe
• the Pin Probe is now finished