cheap_clip_leads

Cheap Clip Leads

How to build inexpensive clip leads for electronics testing

1) The "found" ball-point pen tube:

If you cannot find discarded pen tubes, it is possible to purchase 10-packs of new ball point pens at the dollar store. Almost any small diameter fairly rigid plastic tube will work.

2) Remove and discard the ball-pen tip section. To remove most of the ink I ran a wire through the tube while holding everything under warm soapy water (use rubber gloves to protect your hands from ink stains).

3) Cut the tube into 1.5 inch sections. Insert a length of copper-coated steel MIG (Metal-Inert-Gas) welding wire (use paper clip wire if you cannot find welding wire), into a section of the pen tube. Leave approximately 1/4 inch protruding at one end, and bend a spring handle at the opposite end. Secure this with several tight turns of wire around the pen tube:

4) Adjust the spring handle part so the wire slides smoothly inside the pen tube. Then depress the spring half way and bend a hook in the other end of the wire:

5) Solder a flexible wire onto the spring handle part to serve as a test lead. Put an appropriate connector on the other end of this wire.

6) This is the proof that it works:

Now you have a clip lead which probably only cost you a little time and effort. You should be able to build 10 to 20 of these per hour...maybe more if you are adept with tools.

The handle is not insulated, so these are only intended for low voltage circuits, as would typically be encountered in transistor designs. Operation would probably involve turning the voltage off, placing one or more clip leads, and turning the power back on to take measurements. Turn the power off to place, move, or remove clip leads.

UPDATE:

When you build your home-made clip leads, leave a little wire sticking out on the side opposite the spring/handle. This allows you to use a three-fingered grip (well...two fingers and a thumb) and makes it easier to operate these with just one hand.

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20 January 2009 "Better Home-brewed Clip Leads"

The pictures and text below show the new and improved version of my homebrewed clip leads. These were made from very cheap dollar-store click-type ballpoint pens (10 pens for $1.00 USD).

This is the cheap pen disassembled. The wire in the background is a length of copper coated steel MIG welder wire (you can use a straightened out paper clip if you don't have a MIG welder).

The length of wire is fastened into the clicker mechanism by using hot-melt glue. It sits in the same position as the original ink tube.

The spring is positioned on the copper-steel wire in about the same location as it was on the original ink tube. Bend the end of the spring into a smaller circle and solder it in place on the wire.

A slot is cut in the back side of the pen body. I drilled two small holes and connected them by cutting the plastic with a small knife. This slot is where your test lead wire will connect to the push-wire.

A section of flexible hookup wire is soldered to the push-wire. Measure it's position so the wire will be at the top of the slot when the push-wire is retracted.

Assembly your home-brew clip-grip lead by threading the wire into the slot as you insert the push-wire inside the pen body. Attach your favourite test lead connector to the free end of the test lead wire.

The last step is to bend a small hook in the end of the push-wire. Position this so that the hook is extended when the click-cap is depressed and closed when the click-cap is released. Cut off the excess push-wire, and you are done.

Now you have your very own home-brew click-clip test lead. Given the relatively low cost for parts, you should be able to make up enough for all your workbench testing activities.

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