Wire Wrapping: Not just a guide

Breadboarding, soldering, and even turnkey PCB all have the same goal: To take an idea in your head, a schematic and turn it into a working circuit. But each method comes with some caveats. Breadboarding is unreliable from its spring loaded contacts and useless above a couple kilohertz. Soldering brings health concerns, technique, and space requirements into conflict with each other. And even when done correctly soldering is unreliable due to cold joints and other metallurgical issues. I personally feel that my dream prototyping scenario is a method so easy I could do it form the couch yet comparable to PCBs and other professional level techniques. So what alternatives are there?

Wire Wrap

Wire wrap was initially invented by Bell Laboratories as a reliable way to form electronic circuits. It was used to build the Cray supercomputers and space faring electronics. It eventually fell out of favor, replaced with high quantity production methods such as PCBs. But, wire wrap remains one of the most reliable ways to build a circuit, at the cost of time.

As an electronics hobbyist, I count my production quantity in the tens. Most of my projects are one off prototypes where wire-wraps time cost is similar to the time of etching a PCB or similar. I like to focus on reliability and ease of prototyping. For me wire wrap checks all the boxes.

If the last couple paragraphs got a little boring, rest assured I'm probably asleep in my chair. So why not mix it up a little. Wire wrapping has a lot of information out there about the history of wire-wrap and its mechanics. Why not mix it up a little? Instead of lecturing you like a professor on the benefits of wire wrapping, supply chain demand. Wow, I just put myself to sleep. Let's keep it fun and learn to wire wrap using a simple project many of you reading this have already built on a breadboard. The ubiquitous 555 timer blinker.

Getting Acquainted

Before we launch into our first circuit we first need to figure out what all those things do on the tool. Actually, lets first talk about tool selection.

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For this tutorial, I'm using the WSU-30M tool from Jonard Tools. It is easy to use, has all the features and uses a modified wire wrap that is more mechanically stable. If you want to know more about the different wire wraps look at the resources section at the bottom.

Quick word on counterfeit tools. Just Don't. I'll keep it simple. The authentic tools have built in strippers, wrap tool and unwrap tool. They feel good in the hand and best of all: They are relatively inexpensive. You won't be saving that much money ona clone and you'll be losing a lot of quality in your wraps.

The WSU-30M has two ends: a wrapping end and an unwrapping end. Wire wraps are wire stretched tightly along a wire wrap socket so the wire forms a gas tight joint around the post. I know that its not an exact comparison, but I like to think of it like a crimp.

Steps to a good wire wrap

1. Place your wire in the stripping hole of the tool. Push through about 2-3 inches and pull down and out to strip.

2. On the wrapping end of the tool, if you look down the barrel you should see 2 holes. Push the wire up into the off center hole as high as much as you can push the wire in. The wire should slide into a channel on the barrel of the tool.

3. Push the other hole over the wire wrap socket and twist the tool until the tail of wire you pushed through the tool is gone. When you remove the tool, you should see a nice joint.

4. Just for practice push the other end of the tool (unwrap side) and twist counterclockwise to remove the wire wrap.

Feel free to practice a couple times. Wire wrapping is pretty intuitive and works exactly like you would expect

And Now....... The Project

For this first project I'll break down each wrap step by step. If you feel comfortable going on your own feel free to work off of the schematic. One of my favorite parts about wire wrap is that you can arrange and connect parts exactly as they are in the schematic making life so much easier. I find it a lot more intuitive than breadboarding.

A disclaimer: Some of the components we will be wire wrapping were not designed for wire wrap. If you want this to be an ultra reliable connection, you will need to add a bead of solder to the wrap. For a one off prototype, we should be fine.

And now without further ado let me present (drumroll) the schematic:

And now the step by step guide.

1. Place the 555 timer IC in its socket on some perfboard and place all the components in an order that makes sense for you. Feel free to play around.

2. Connect pin 1 to ground

3. Connect pin 2 to the capacitor (check polarity) and then to ground

4. Connect pin 2 to pin 6

5. Connect pin 3 to R1

6. Connect RI to the LED and then to ground. Make sure to check the polarity.

7. Connect pin 4 to pin 8

8. Connect pin 6 to R2 and then connect R2 to pin 7

9. Connect pin 7 to R3 and then connect R3 to pin 8

10. To test your circuit apply 5V to pin 8 and connect pin 1 to ground. I used alligator clips to grab on to the wires

And the best part: All of this prototyping was safe (no lead fumes) and could literally be done anywhere.

Conclusion-ish

Wire wrapping does everything you'd expect a prototyping methodology to do.It is reliable, and can tackle all my RF and analog projects. Breadboards certainly cannot. It can be ultra compact (think of wire wrap like a PCB with infinite layers) and I can connect parts/ lay them out as they are in the schematic. No more weird schematic to breadboard translation. Wire wrapping is a great way to prototype and I can't recommend enough that you try it. Good luck! and Have fun with that wire wrap!

Resources

Here is a link to a technical document on wire wrap

Here are couple more training guides explaining how to use the tool

• https://learn.sparkfun.com/tutorials/working-with-wire/how-to-use-a-wire-wrap-tool
• http://www.ee.nmt.edu/~tubesing/ee101/labs/14lab/WireWrappingTutorial.pdf

Here is a link to a video on wire wrap tool selection

Here are some links to buy the tool I used (PN: WSU-30M) I highly recommend it and please feel free to purchase it from whatever distributor you prefer.

• https://www.specialized.net/jonard-ok-industries-wsu-30m-wrap-strip-unwrap-tool-30awg-mod.html
• https://www.digikey.com/product-detail/en/jonard-tools/WSU-30M/K105-ND/5986