Wiring Pen





Introduction: Wiring Pen

Attach a spool of wire and a hypodermic needle to a ball point pen barrel to make an aid to make point-to-point wiring easier to do. The board shown is a microprocessor system board with a 8085, 2764 and 6464 - that is, the CPU, EPROM and RAM - and some additional glue circuitry.

Step 1: The Parts

A hypodermic needle. Get the disposable type with a plastic collar, as this will need to be cut down to make it fit in the nozzle of the ball point pen.

A (used) ball point pen. I acquired one with a metal nozzle as it would probably last longer.

The spool of enamelled wire was from a relay, 12 V changeover contacts - the rest of the relay was dismantled with care not to damage the spool of wire. Other sources are transformers and rf chokes.

Some two component epoxy to cement the needle to the nozzle.

A screw long enough to hold the spool of wire (not shown)

Step 2: Putting It All Together

First, some copper wire was placed inside the needle to prevent its bore from closing up, and its sharp point was ground square on some fine emery paper.

Its plastic collar was cut to make it fit inside the nozzle of the ball pen, and it was fixed in position using some two component epoxy glue.

The screw was heated and poked into the side of the pen, and on cooling it was unscrewed. The spool of wire was placed on to it, and it screwed back on. The wire was led through the body of the pen and out through the needle tip.

The thin tip of the wiring pen enables it to be used to snake the wire through tight spots, and to make connections to tightly packed integrated circuit socket pins.

To make a connection, the (enamelled) wire is wrapped once or twice round the ic or socket or component pin. Heating the joint, and applying some solder will complete the joint - if you are lucky enough to find some 'self fluxing' enamelled wire. This sort of wire is coated with the sort of enamel that changes to flux when heated to soldering temperature.

I prefer to use normal, tough enamelled wire, as the chances for accidental short circuits is reduced while using this type of wire. The joint has to be heated and then the enamel can easily be scraped off using a sharp edge of a small jewelers screwdriver. Then solder is applied and the solder will attach to the freshly exposed copper.

I used to make all my prototypes this way, until the coming of the flash microcontrollers with on chip program and data memory, which does not need this scale of wiring in order to work.



  • Paper Contest 2018

    Paper Contest 2018
  • Pocket-Sized Contest

    Pocket-Sized Contest
  • Science of Cooking

    Science of Cooking

We have a be nice policy.
Please be positive and constructive.




aren't hypodermic needles illegal?

That's ridiculous. What do you do if you're diabetic?

If they are illegal where you live, you could probably get away with using an inflation needle, like you would use to pump up a soccer/volleyball/basketball with.

Not in Canada at least. We can go to any hardware, drugstore, or even the dentist for just one or two. I can also find them at pet stores sometimes, and the flooring department at most warehouse stores. You use the large 50CC ones for flooring, to apply glue to area's that are bubbled. Either way, they will have those metal tips you're looking for.

That depends where (and who) you are. some places put legal controls on the possession and transfer of hypodermic needles. this has changed with the spread of HIV Blunt hollow needles are legal most places, they are used in things like inkjet refill kits. It may be possible to roll a needle for this instructible from stainless steel shim (eg the sliding cover of a 1.44MB diskette) as the needle is just used as a guide for the wire.

why would they be? unless they are filled with a substance that is...

the last time i checked you can't buy hypodermic needles off the shelf anywhere legal. and besides how would you get a hold on one legally

eerrmmm just go to the chemist(UK)and ask for a box of them.

I got a free one from a pharmacy to apply acetone to an acrylic box joint, and I think the pharmacist actually believed me when I said it was for a science project. Beforehand I got turned down by a walk-in care place--they did not believe me.

You can also buy non-super-sharp ones in bulk from mcmaster or places that sell solder-paste dispensing syringes.

I'm sure all the Type I Diabetics are plenty of proof that they're NOT illegal. Just because something is not convenient or easy to find doesn't mean it's illegal.