Point to point or wire wrap?

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Rbeckett

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Bronson
For the prototype boards I am building what method do you guys think will provide the most flexibility and repairability? I have a large supply of .1 pitch perfboard and a good supply of vero board so it is just a matter of choosing the connection style. I am thinking wire wrap may be batter than point to point soldering in case I want to change a component or circuit without trashing a board and having to start over with placing components. Any signifigant negatives to this approach other than being time consuming and error prone if you get in a rush? Thoughts and Comments? Thanks for looking and joining the discussion.
Wheelchair Bob
 
I can't imagine that no one has not waided in with at least one opinion. I think that as this projects evolves, maybe a seperate board with IDC connectors is gonna be the way to go. Have each major function or circuit on it's own board and connect it to the MCU as a plug in or shield type of set up. The neatly routed and zip tied point to pont wiring with proper attention to color coding will work very well for developement and prototyping. If I let the magic smoke out it will also be on a smaller scale with less components to recheck and replace if damaged. Thinkin out loud again, I still have plenty of time to decide since I am still waiting for Chinese customs to release my stuff. Too bad they are so inconsistent. One shipment in 9 days another is now over 30 days, no rhym or reason. Oh well that was part of the bargain when I started the project, so nothing lost, so far. Still looking for opinions or general comments. Any of the more experienced board builders have a different point of view or take on the proposed solution? Thanks!!!!!
WCB
 
I'm currently moving house so my project is on hold. I was in the middle of trying to use an ultrasonic distance sensor to determine volumes in my HLT. All my prototyping so far has been initially done on a prototyping breadboard and then soldered onto veroboard. I did consider those copper square pad boards and doing wire wrap for the connections but that would mean IC sockets for every component so i said sod it!

Any more detail on yer project?
 
Brewer G,
Just started drafting out the circuits and doing the resistor and cap calculations. I started with the simpler stuff first in the schematic and will progress to the PID interface and thermocouple amplifiers as I add to the diagram. Most of the stuff i have drawn so far is straight forward drive a relay to operate a solenoid and do it at TTL voltage. The solenoids are 100 VAC so I am using the smaller 25DA SSR's for those. Not much else really happening, too hot for me to be out in the shop, so I have been trying to draw the schematic and continue to study the intro to 16f877A microchips and C entry level programming. My brain hurts, but I'll get it sooner or later...
WCB
 
When I develop small things I start out on a breadboard for proof of concept. That allows you to change things up quickly. Once I get the circuit sorted out I then move to protoboard and solder in point to point.
 
If you are planning on building your own amp for thermocouples here is some info that may be useful. I spent some time at work improving the amp circuit we use for our thermocouple sensors. We started with the opa2379 opamp but switched to the opa2333 because it has zero drift and much lower offset voltage. We use a basic diff amp circuit with a voltage bias of 1/2 the ADC's Vref. The amp has a gain of ~30 and uses resistors with 0.1% tolerance. Even with the better opamp and tight tolerances on the resistors we still get error that needs to be accounted for. To do this we do a one time calibration in manufacturing by shorting the input to the amp and sampling the output. Each time the thermocouple is sampled we subtract the calibration value from the measured value to correct for the amp's error.
 
Hi

A lot depends on what you are using for parts / trying to do. For analog stuff - wire wrap is somewhat painful. For a mass of TTL gates it works pretty well. Most of what I do gets done up on prototype board(s) and then shot as a pcb. There are a lot of cheap places to get small runs of double sided pcb's these days.

Bob
 
CB,
The point to point soldering is a real PITA. it's very hard to get the solder to form a track on the back of the board between through holes. Wire wrap or some variation of it is probably going to be easier and less prone to errors and shorts. Did a few practice boards and what a PITA, plus the posibility of overheating the components on the boards. Let ya know how the wire wrap hybrid approach works after a couple of test boards too.
Wheelchair Bob
 
Wheelchair bob, solder isn't meant to bridge gaps. It is actually meant to do the opposite by whicking up the through hole. I have tried this before too and got frustrated quickly. I use the extra lead from through hole components as a trace to connect over to other pins on the backside of the perf board. For long runs or components with real short leads I will use bus wire. I also have some bus wire insulation to prevent wires from shorting to each other. I can get the PN's for the bus wire and insulation I use once I get out of bed.

Here is some pictures of my brew control breakout board that plugs into 1 of the expansion ports on my microcontroller. I have a PFET to drive my SSR with an LED to show when it's on. I also have a dual opamp to subtract off the wire resistance for 2 separate 3 wire RTDs.

image-1507054446.jpg
 

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Hi

These guys:

http://www.4pcb.com/barebones-pcbs.html

Will do an overnight PC board run for less than what you pay for the wire wrap base board. You also don't have to pay for all those wire wrap sockets....

For about the same price as the wire wrap base board and a handful of sockets, they will do a $33 board in a couple of days that has solder mask and silk screen on it.

http://www.4pcb.com/33-each-pcbs.html

Unless you have a major inventory of multi colored wire wrap wire, figuring out which wire *actually* goes where when you are done is more of a hassle than following a trace on a pc board.

Yes indeed you do need to layout the pc board. The software is free, it's fairly easy to use. If you are dealing with the sort of stuff that you would wire wrap, it's pretty straightforward.

In both cases (bare bones and $33) you want to lay out one board you can use for several things. Depending on what you are doing that may or may not be practical.

There are a *lot* of other places doing the same thing. Some with better prices. I've used these guys a lot and never had a problem with them.

Bob
 
Crane, and CB,
Thanks for the help on the board deal. I knew solder wasnt meant to draw with, but figured a small hole to hole bridge would be fairly simple, especially since I seem able to do it accidently pretty often. After that exercise in Frustration I decided to do something similar to Cranes wired board in the second pic above. I have several colors of solid and stranded wire from Radio Shack so unraveling the wiring will be one order of magnitude easier if needed. I also try to follow standard wiring conventions like red is Pos, Black is Neg, Green is ground, and signals are various other colors. Helps a lot. The biggest issue is trying to install too many components at the same time instead of following the normal electron flow in each circuit. It is certainly a study in patience and tolerance to say the least. But...This is why I wanted to learn electronics in the first place. I really love the Dr Frankensteeen look and feel of doing stuff like this from scratch too. Thanks for the help and input, because I never built anything with a practical real world application before this. I did the "Hello World" and flashed the LED's in all of the experiment texts from All About Circuits which gives a pretty strong practical application to basic electronic theory, with a working circuit to experiment with. Then it becomes an exercise in succesfully putting a bunch of circuits together to do something usefull. Thanks for the Help and encouragement.
Wheelchair Bob
 
Hi

If you take a close look at the picture of the board, there's a meathod to the madness of wiring it.

You use a spool of bare solid wire and a spool of teflon tubing. Wire goes down / cut to lenght / cut tube to lenght / put on wire / solder other end.

Much easier than any form of insulated wire. The teflon is almost impossible to melt with a soldering iron. No matter what you bump, no charred insulation. A 1 lb spool of bare wire lasts pretty much forever. Teflon tube is a much smaller spool, so you might go through one a year.

Bob
 
I did a bunch of wire wrap stuff back in the day, and I think it's great for prototyping, but ONLY for prototyping. All my old wire wrap boards fell apart after a while.
 
CB,
do you have a vendor that you use to get the teflon tubing from? I can get the enameled wire or bare wire from Radio Shack, but much prefer the concept of no charred insulation too. TIA for the info.
WCB
 
carlisle_bob said:
Hi

If you take a close look at the picture of the board, there's a meathod to the madness of wiring it.

You use a spool of bare solid wire and a spool of teflon tubing. Wire goes down / cut to lenght / cut tube to lenght / put on wire / solder other end.

Much easier than any form of insulated wire. The teflon is almost impossible to melt with a soldering iron. No matter what you bump, no charred insulation. A 1 lb spool of bare wire lasts pretty much forever. Teflon tube is a much smaller spool, so you might go through one a year.

Bob

Exactly how I did it. I used the same Teflon insulation that is reference later. For most of the connections I use the extra lead from the through hole components where I pull the component lead through the hole and bend it over in the direction of where it is going then solder down the lead in that hole. I then cut to length, cut insulation, slide insulation on, and then solder other end on lead. I only used bus wire on a handful of the longer runs.

As CB explained the Teflon doesn't melt like regular wire insulation. I have had the frustration of having the insulation on regular wire melt back exposing more of the bare wire causing it to short to something else.

You could easily color code the Teflon insulation with a sharpie to make debugging easier. For these simple circuits I don't find that necessary but on larger things it can be very helpful. I bought a kit car once where the guy before me replaced all of the wiring with red wire. I went mad trying to find a short in the dash.

weirdboy said:
I did a bunch of wire wrap stuff back in the day, and I think it's great for prototyping, but ONLY for prototyping. All my old wire wrap boards fell apart after a while.

I have seen computer chassis that have spent years in military aircrafts where wire wrapping was used on the backplane for configuration jumpers. If you use a wire wrap tool it can withstand the intense vibrations that these aircrafts endure. But I agree that for our applications point to point soldering is much more practical.
 
Exactly how I did it. I used the same Teflon insulation that is reference later. For most of the connections I use the extra lead from the through hole components where I pull the component lead through the hole and bend it over in the direction of where it is going then solder down the lead in that hole. I then cut to length, cut insulation, slide insulation on, and then solder other end on lead. I only used bus wire on a handful of the longer runs.

As CB explained the Teflon doesn't melt like regular wire insulation. I have had the frustration of having the insulation on regular wire melt back exposing more of the bare wire causing it to short to something else.

You could easily color code the Teflon insulation with a sharpie to make debugging easier. For these simple circuits I don't find that necessary but on larger things it can be very helpful. I bought a kit car once where the guy before me replaced all of the wiring with red wire. I went mad trying to find a short in the dash.



I have seen computer chassis that have spent years in military aircrafts where wire wrapping was used on the backplane for configuration jumpers. If you use a wire wrap tool it can withstand the intense vibrations that these aircrafts endure. But I agree that for our applications point to point soldering is much more practical.

Hi

There are a lot of DEC PDP-8's and PDP-11's still running around with the original wire warp backplanes. The stuff can be reliable. It's just painfull to trace out when you have twenty layers of wire running around ...

Bob
 
Quite a few military wiring panels are wire wrapped. They appeared to have been wrapped with a special tool to insure tightness and then soldered. Multiple levels are a PITA, but can be overcome by using a terminal strip with loops to split the wiring neatly and in a logical manner. This also gives you a circuit test point for troubleshooting later on. Just some thoughts on simplifying a complex wiring pattern.
Bob
 
The special tool is just a wire wrap tool. sparkfun has a cheap one. They can get quite a bit more expensive.

http://www.sparkfun.com/products/68

They work by striping an inch or more of single strand wire. The bottom of the tool has 2 holes, one in the middle and one off to the side. Stick the entire inch or more of stripped wire into the hole off center. Then place the header pin in the center hole. Hold down the wire by the base of the header and twist the tool until all of the stripped wire is wound around the pin. Its quick and easy. All the wire wrap tools I have seen have a wire stripper built into the side of the handle.

I have never seen them soldered though. The wire wrap tool will hold it on good enough by itself.
 
Hi

The *good* wire wrap tools are air dirven :D

To get a tight wrap you need to properly match the bit on the tool to the post size and the wire diameter. You also need to replace them when the go/nogo gauges say so. Yes that's all expensive to do...

Bob
 
carlisle_bob said:
Hi

The *good* wire wrap tools are air dirven :D

To get a tight wrap you need to properly match the bit on the tool to the post size and the wire diameter. You also need to replace them when the go/nogo gauges say so. Yes that's all expensive to do...

Bob

Sounds like complete overkill for homebrewing...
 
Radio shack has the wrapper tool and 3 different rolls of wire for just about 20 bucks, hard to beat that price. It's the same one SFE sells for 16 bucks plus wire. Pneumatic would be fun, but way overkill for one or two boards.
Bob
 
Teeheehee

One guy signing his name (in a thread... who does that?!?!) Bob replies to another guy signing his name Bob. How adorable. From now on I'm calling you the Bobs.

bobs.jpg
 
I looked at the reviews on the Radio Shack wire twister and it had some pretty harsh reviews about it being flimsy.
 
Sounds like complete overkill for homebrewing...

Hi

Overkill indeed. It is how the military and others get a lot better wire wraps than you get with most hand tools, and why some wire wrap stuff lasts for many decades.

Bob
 
I read that too, but it is the same identical unit they sell at spark fun for 3X the money. If youre gonna get a crummy tool might as well pay 6 bucks instead of 16. I think a lot of the reviews were also by inexperienced wire wrappers who pullled it too tightly and stretched the wire in half. 30 ga is small enough to nip off with a fingernail if yours are long enough. Higher quality wire that is solid and seperate from insulation looks like the best way to go. I think they may have also nicked the copper where they cut off the insulation too. The teflon tube is a great idea, because I always manage to char something along the way. You ought to see my solder iron cord. No burn throughs, but lots of spots I got hot here and there. Come to think of it I still need to order a new Iron too.
Bob
 
Teeheehee

One guy signing his name (in a thread... who does that?!?!) Bob replies to another guy signing his name Bob. How adorable. From now on I'm calling you the Bobs.

bobs.jpg

Hi

Been doing it that way in threads for 30+ years. To late to change now :ban:

Bob
 
OK, I'll be wheelchair Bob. I use both so it's no big deal. Now I gotta go put new parts away. My connector shipment arrived this morning. A huge selection of IDC and crimp style connectors from 2 pin to 10 for the initial order. Got a bit of sorting and binning to get done before the other selections arrive too. Need a cheap alternative to 40 dollar bin box cabinets. Cheap and too flimsy for way too much money. Any ideas?
Wheelchair Bob
 
OK, I'll be wheelchair Bob. I use both so it's no big deal. Now I gotta go put new parts away. My connector shipment arrived this morning. A huge selection of IDC and crimp style connectors from 2 pin to 10 for the initial order. Got a bit of sorting and binning to get done before the other selections arrive too. Need a cheap alternative to 40 dollar bin box cabinets. Cheap and too flimsy for way too much money. Any ideas?
Wheelchair Bob

Hi

Cheap *and* flimsy = plastic egg cartons. Price is right though.

Bob
 
Really want a drawer system to put parts values in order and seperate the different components properly so I can inventory and replenish at a glance easilly. Since I have been on the cheap assortment jag on Ebay I have trippled my bench stock to nearly 1000 different components of multiple values and construction specs like TO-92 and To-220 along with resisters in 1/4W 1/2W,. and 5 watt E12 series. I figure I need at least 4 of the 60 drawer cabinets already, plus a few more for the remainder of the stuff I plan to add in the future. Ultimately I want to just be able to sit down and build without ordering a bunch of parts to complete the project. I will probably have to order the main chip or logic chips, but the rest of the components will eventually come from what I have on hand. It's a huge undertaking, but I have a bit of time and enough patience to slowly accumulate enough different assortments to allow that to happen eventually. I have a 50.00 dollar monthly parts accumulation budget so I try to find the best deals I can on various assortments of basic components to expedite that happening. I can usually get three of four assortments every month to add to my bench stock, sometimes more sometimes less but it averages out around 4 pretty consistenly so far.
Wheelchair Bob
 
Hi

Be careful with the bench stock stuff. Once you get past the first level of stuff, you'll buy a lot of things you never use. I find it better to simply double up on an order for what ever I need. That way I have plenty to to complete the project and the stock of stuff I actually use builds up.

Bob
 
Really want a drawer system to put parts values in order and seperate the different components properly so I can inventory and replenish at a glance easilly. Since I have been on the cheap assortment jag on Ebay I have trippled my bench stock to nearly 1000 different components of multiple values and construction specs like TO-92 and To-220 along with resisters in 1/4W 1/2W,. and 5 watt E12 series. I figure I need at least 4 of the 60 drawer cabinets already, plus a few more for the remainder of the stuff I plan to add in the future. Ultimately I want to just be able to sit down and build without ordering a bunch of parts to complete the project. I will probably have to order the main chip or logic chips, but the rest of the components will eventually come from what I have on hand. It's a huge undertaking, but I have a bit of time and enough patience to slowly accumulate enough different assortments to allow that to happen eventually. I have a 50.00 dollar monthly parts accumulation budget so I try to find the best deals I can on various assortments of basic components to expedite that happening. I can usually get three of four assortments every month to add to my bench stock, sometimes more sometimes less but it averages out around 4 pretty consistenly so far.
Wheelchair Bob

RESPECT! I don't know anything you said there...:tank:
 
BC,
I got that. I am still working on all the basic caps, resistors, connectors and really common stuff right now. I figure it will be several months before I get to any kind of specific type of components. I always buy a few or 5 of something I need too, so I will have it the next time I mes with it or in case I melt it or damage it soldering. Keeps my stress from stupid pretty low that way. Thanks.
Wheelchair Bob
 
CB,
Ordered all the correct wire wrapping tools and correct wire to do it properly on Sunday. Since there seems to be an issue with the quality of the Radio Shack wrapping tools I bought several so I could sort through and find a good one and keep swapping out the rest till I get a set that work properly. At 3 1/2 bucks each I ordered a half dozen. Surely I will get at least one that works properly. I think the bad reviews were based on inexperience as much or more than poor quality tools. Like mentioned eralier it is very easy to pull 30 Ga apart with just a fingernail and any nicks at all would creat a weak spot, so I got some wire without insulation and some teflon tube to slide over it along with the insulated wire too. I'll let ya know how it goes with the RS stuff once it arrives. My electronics bench has been cleaned and expanded a good bit again so I have plenty of room for my big elbows and the magifying glass I have to have to see the components. It's a ***** getting "old man" eyesight. Just figured I would keep ya up on what I am up to and attempting to make happen. I do intend to solder all the wraps to make them a better electrical connection and to insure good long lasting connections through out the system. A little added insurance never hurts. My connector collection should be here today too. 2 pin to 64 pin connectors, headers, IDC and crimp style along with ribbon cable of the appropriate pitch and wire counts to employ as interconnection and basic wiring harnesses through out all of my projects. I got at least 100 of each connector in male and female with all of the required hardware and a special crimper for IDC cable. That should keep me busy for a while...
Wheelchair Bob
 
Hi

I'm not sure that doing solder + wire wrap is the way I would have picked to go. You get most of the problems without many of the benifits. You do indeed take care of most wraps coming undone. You still likely have the issue of breaks right at the first turn of the wrap. I'm also not real sure how Kynar does with solder heat. I suspect it's fine, but I'm not sure.

30 gauge is smaller than what I've used in the past. Most of the tools I've seen have been set up for 26 or 28 gauge. I've never used the Radio Shack version, so they may be different.

Bob
 
CB, Where are you getting the larger guage wire wrap tools from? I would like to go larger than 30G, but that was all I have seen anywhere so far. Thanks.
Wheelchair Bob
 
CB, Where are you getting the larger guage wire wrap tools from? I would like to go larger than 30G, but that was all I have seen anywhere so far. Thanks.
Wheelchair Bob

Hi

The stuff I used was made by Ingersol Rand. Most of them came by various odd routes from DEC plants. I picked up the last one in 1978 I believe...

Bob
 
I'll have to look at IR and see if the still make any of them still available. I would really like to fo to 26-22 Ga if I can find the correct tool. There seems to be a plethora of info on the web about old school wire wrap, but very few links or suppliers mentioned to follow up on or find. I can just go ahead and use my laser printer and make a board that way, but I would prefer to get the circuit fully functional before I burn a board and waste a bunch of time doing that. I can do a board in a few hours, once I get a proven circuit and tighten the layout up to shorten all of the runs and include all the smoothing caps and diodes in appropriate locations. Thanks for all the help and guidance on the old school style of building boards so far.
Wheelchair Bob
 
Hi

I really do think that the overnight board outfits are a pretty good option. Do your prototyping with a plug board and go to a pcb. Less cost that the whole wire wrap approach.

Bob
 
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