Neelandan,

Not a bad implementation. How do you go with the wire changing direction as it passes over the top of the pen barrel?

Regards,

Alan

My version of the "Wiring Pen(cil)":

http://www.instructables.com/id/Wiring-Pen/

Interesting website mate, lots of neat hardware hacks!

I bought 300 meters of Kynar wire from http://www.netpcdirect.co.uk/kynar_wire.php

I am very happy with it- easy to solder, quite thin to put it with insolation threw chip pin hole. When I misplaced ATMEGA16, only Kynar wire saved me from new PCB making. Here is the result: http://www.vabolis.lt/2008/04/06/kynar-laideliu-betvarke/ :)

John,

Thanks for that.

> $40, ouch! I think I'll just keep building my own for now.

Regards,

Alan

Alan,

The Roadrunner pencils are listed as available

on the Farnell website.

http://au.farnell.com/jsp/search/browse.jsp?N=1504+500001+1004993

Kevin,

Your question made me curious enough to try testing every thin gauge wire I have in stock. The results are here.

The "Versa Australia" blue labelled black spools DSE used to sell were the best, at least for 125 um and 200 um gauges. "Real" thermaleze didn't test as well, but that isn't meant to be self-fluxing AFAIK, just easy to tin at the ends.

The good news is that almost every type of wire you can get in AU electronics stores will tin through the enamel at 380 °C or more. So if your iron can go above 400 °C just crank it up and all should be well.

A Nylok nut would do the job for sure. It isn't so much it loosening that is the problem, just control of the friction against the felt. You don't really even need it, tilting the pen controls the tension easily. It is perhaps easier to get higher tensions without scratching the enamel with a bit of resistance at the spool, especially for finer gauges which will bend around the tip easier.

Regards,

Alan

Arv,

The idea of having multiple wire feeds on the one tool is great, swapping the tools is what consumes the most time, anything that reduces your need to would save a lot.

Putting a cutter on the same tool occurred to me as well, but I was worried that I might accidentally nick the wire as I pulled it. (I thought about attaching a small diagonal nipper to the pencil to save having to swap hands, but it isn't too bad if you secure the board well, you can keep the pencil in one hand and the nippers in the other.) Adding one of those triangular rubber grips you can get for normal pen(cils) would help you control the absolute attitude of the tip with respect to the direction the wire is flowing and perhaps make it easier to control with an inbuilt cutter. Hypodermic needle sharps have oblique ground edges that are very sharp by design in one direction, they might work in that application too. They are stainless steel and should reject tinning accidentally better than the brass. Syringe and needles are available very cheaply from chemists - the finger wings of the syringe would facilitate making a bobbin holder, but the barrel might be a bit short for good ergonomics.

Putting a notch in the tip or using multiple tubes to allow easier wrapping, like wire-wrap is interesting. I rather like wire-wrap, I have the (manual) tooling and a small supply of Kynar wire, but the sockets are expensive and in fairly short supply of late.

Magnet wire works fine with SMDs, and prototyping without adapter boards almost demands it. I rather like the hybrid of veroboard, matrix and doughnut board and magnet wire interconnections for complex digital prototypes. I often mount pieces of veroboard or doughnut board on top of matrix or unetched PCB (or a tin-can lid!) with superglue and use that for surface mounting components (even leaded ones), especially in hybrid RF and digital/AF circuits where the RF bits go on unetched board and the slower/uglier/denser stuff on the other boards. It is quite practical to build digital circuits RF-style by gluing the chips straight to unetched PCB and bending down the GND pin. Makes grounding and decoupling very easy with either SMD or leaded 100 nF caps, but you can't socket the chips and rebuilding it if you kill one is nearly impossible, for SMDs you pretty much have to live with that, but little islands of board with sockets mounted to the copper side work well, you can't wrap them, but you can just stick the end of the wire into the solder blob and hold it in place while it freezes, much like you do with SMDs.

That reminds me - I must buy some Kapton tape, which is available in single and double-sided silicon adhesive (and none at all). That would be handy to hold down wiring and mount larger chips without superglue which is pretty deadly if you get it wrong and messy when it "fumes" the rest of the board and shows up all your fingerprints no matter how careful you've been.

For MCUs I always have them socketed, I rarely use ISP headers and generally just pull out the chip to reprogram it (initial program development usually happens on a solderless board so reprogramming is normally just minor revisions or data changes). I use stacked sockets to protect the legs, if you trash the socket you can just replace it, limiting the number of cycles the DIP legs need to endure. So far I haven't had any problems with sockets strays or bad connections, but I only use the machined pin type.

Anyway, enough waffling. Everyone has their own particular style of breadboarding. My breadboards are never pretty, but they work and seeing as most of my builds are one-off I never bother with PCBs or fancy layouts, it all gets hidden inside a box, (or shown off in all its ugly glory to my mates :).

Regards,

Alan

Nice one. The enameled wire I have requires quite a hot iron, at least a No 7 tip, No8 better. Did you manage to find wire that requires a lower temp?

Also have you considered using a Nylex nut (not sure of the spelling) in place of the dome nut, they are self locking and will not become loose. (Bunnings have them)

Very good project. In the 1970's era there were many of these type projects (I still have a couple of my own homebrewed wiring pencils) when solder-through insulation became available at reasonable prices.

Some further ideas from the 1970's era...

1) Use a steel sports-ball inflating needle and sharpen the end for 'clipping' off the wire at the end of a run.

2) Use a dual-tube arrangement of tubes at the tip so you can 'wrap' connections by twisting or spinning the wire pencil.

3) Add a slot in the wire pencil tip to hold the wire while you manually wrap it around a terminal.

4) Make this pencil dual-spooled and double-ended so you can change wire colour or gage by simply flipping the tool end-for-end.

.

This brings back lots of memories from the era when we used to use wire-wrap sockets and perforated PCB for making up circuits.

_._