Can you tell how wire wrapping is done?

Question

and some pros and cons?

Answer 1

Wire wrap uses a solid 26AWG wire coated with a thin teflon insulation. Perforated circuit board with .1" hole spacing typical is used to mount bifrucated pins. The pins are placed on the circuit board in locations where a discrete component lead is to be mounted by soldering to the bifrucated end.

IC's may be mounted using special wire wrap sockets .

The wire wrap pins and sockets protrude below the circuit board approximately 1/2 to 3/4 of an inch. This pin lenght will allow several wrap connections to be made to a single pin if desired.

A special tool is used to Cut and strip off insulation from the wire. You can doo this with regular tools but not as quickly. A standard lenght of insulation is stripped from the end. (About an inch) The stripped wire is inserted into a wrap tool which is a rod with two holes drilled in teh end. One hold is drilled in the center and accepts the pin, a secon hole is drilled just off center and accepts the stripped wire.

The tool with the wire inserted into the outer hole is placed on the pin and twisted clockwise. as the tool rotates abotut the pin the wire wraps itself around the pin very tightly and establishes a mechanical and electrical connection to the pin.

THe advantages of wire wrap are in protottyping where a durable circuit may be constructed quickly yet changed easily. The circuit is durable unlike a solderless breadboard where connections can be easily pulled out.

Since connections are not soldered a connect may be undone by simple unwrapping the wire from the pin. A special tool which has a left hand spiral is used to quickly remove a connection.


Advantages of this constructionis are quick construction, larger construction with discrete components allows easy connection of test instruments. Wire comes in several colorsand may be purchased in precut and stripped lenghts or by 100 foot spools

Disadvantages Expensive... A good set of wire wrap tools will cost around 100 to 150 dollars and spools of 100ft wire are about $15 to $20 each. Solid wire is used and can take some bending but still breaks if bent multiple times.
It is difficult to reuse wire once it has been cut to size and wrapped. With car is is sometime possible to rewrap a single connection if it needs to be moved but more often than not the wire breaks during the rewrap. Some mewer chips are not packages in DIP form so adapter boards need to be purchaed to mount surface mount components onto

Construction is point to point so construction of a single circuit is not bad. How ever if multiple circuits are to be constructed then consider PCB as a quicker solution.

Since wire wrap is point to point RF and high frequency circuit costruction can be effected by the wire layout.

Answer 2

The two previous posts provide a lot of valuable information. I would just like to add a few comments.

If you have difficulty visualizing things in a mirror, might I suggest using socket IDs. What they do is slip over the wire wrap pins protruding through the bottom of the perforated board and will identify the pins. When the DIP is installed vertically, the top left pin (or bottom right pin) is typically pin 1. When you flip the board over left to right, the top right pin (or bottom left pin) becomes pin 1. If you flip the board over top to bottom, the top left pin becomes the bottom left pin, etc. Plus, you may write on the IDs to identify which device it is. If you prefer not to purchase IDs, you may use masking tape to identify parts and to label the pins.

Using multiple colored wire helps you identify the traces easily. This is great for power, ground, clock, or other important signals.

My personal preference has to always attach ground and power wires first. This lets you control the power distribution easily. Plus, installing the power wires help hold the sockets and socket IDs in place.

If you know that certain parts of the circuit are known good (for instance, a data bus), wrap them first. That way, if you have to change any of the questionable parts of the circuit at a later time, the wires will not be buried under the known good wiring.

Wire wrapping provides a limited number of connections per point. When wrapping multiple connections, plan accordingly.

The perf board, sockets, and socket IDs may be reused; however, not indefinitely. Therefore, if you use wire wrapping to prototype a project, you may disassemble the project when you are done and reuse everything. You may also reuse the wire. I recommend clipping off the curly ends that were previously attached to the post and restripping the wire. While the wire does become shorter, it is reuseable for a shorter trace.

If you are on a budget, might I suggest Radio Shack. They sell a hand held wirewrap tool (if you take of the palm support, there is a small wire stripper inside for stripping the wire for you) for about $7. Plus they sell 50ft of 30 AWG wire for about $4.

Overall, wire wrapping is a great tool for prototyping and one of a kind builds. You initial cost for materials may be a bit high but they will pay for themselves in the long run.

Answer 3

All components are mounted on wirewrap sockets. The wire wrapping tool can be powered or unpowered. Of the manual-operated tools, there are 2 types. The first requires pre-stripped and pre-lengthened wires which are connected one at a time. Daisy-chain requires 2 wires on a post. The other is the "Slit-N-Wrap". This type has a spool of insulated wire mounted on it. The wire runs down inside the tool to the bit, which, when turned on a wirewrap post, slits the wire where it makes contact with the post. You can daisy-chain with this type, wrapping from one post to the next to the next. Once a node is done, a tiny chisel tool is used to cut the wire. I have this type, much faster to use.

To wirewrap a board, design you parts layout similar to how you would do a PCB version. Try to group components such that yuou minimize lengths of wire runs. Mount the sockets on the perfboard. Do not solder the socket pins as you will ruin the post for wrapping.

I use a copy of the schematic and carefully draw over the schematic wires with red pencil as I do the corresponding connection on the board. You have to be very methodical and careful on a complex board. Avoid making diagonal runs, keep the wires orthogonal. Do long runs first, and the crossing shorter runs will keep the long wires in place.