Prototyping -- between breadboard and custom PCB

Forum 2005-2010 (read only) Hardware Interfacing
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I have recently been developing an Arduino-based project, my first non-trivial electronics design effort. I could use some advice on prototyping techniques. (I have lots of software experience, but not much practical EE knowledge to date.)

I have a breadboard implementation of my system nearly completed and now need to make it a bit more robust. I'm not ready to design a custom PCB, as this is (for now) a one-time effort. But it will be the basis for a public installation, and so it needs to be a lot more solid than a collection of breadboards with jumper wires hanging out all over the place.

I know that the intermediate step is a prototype PCB with components and connectors soldered on to it. What I could use advice about is how to implement it.

  • Components.

I can figure out how to lay out all the components and mount and solder them on generic though-hole boards. And I can envision soldering wires between them to implement the circuits I've designed. With the generic boards I have looked at, I am not clear how to get electrons flowing from the pins of one component to another, though.

Some of the boards have adjacent holes electrically connected via pads so you can just solder a wire into a hole next to a component pin and then run the wire to a hole adjacent to the next component's pin. And I have seen boards with all holes connected via traces that you cut to create circuit paths. But there are limitations inherent in both of those schemes.

It seems the most common kind of proto board simply has a single hole per pad. So, how do you make connections? I could imagine getting some solder to flow across the gap to an adjacent hole, but this seems tricky and not exactly a best practice.

What is the right strategy for this kind of prototype?
.

  • Off-board connectors.

There are a bewildering number of options. I've been using RJ45 connectors with breakout boards on my breadboards. This is partly because I have a lot of ethernet cables around, and partly because some of the connections need to go a meter or more in distance and the twisted pair wires in Cat5 cables are good at preventing signal noise, I understand.

At the other end of the spectrum, I can also see how to use female headers soldered on boards and wires soldered to corresponding male headers to make my own custom connectors. And there are all sorts of other manufactured connectors in between.

On the roll-your own header route, it seems very tedious to solder lots of wires to the male header pins; at least I haven't found a good way to clamp the wire to the pin while using my other two hands for the soldering iron and solder.

And with the other connectors, like RJ45 breakouts, there is still the problem of getting wires from the connector pin-outs to other components on the board, just as with the intra-board connections mentioned above.
So, am I missing some obvious things?

All advice gratefully received.
Thanks.

.andy

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The easiest thing you can do is just move everything into stripboard - Stripboard - Wikipedia

There are a few types, as you have mentioned. The ones where you have to cut the traces suck. There are some that mimic a solderless breadboard by having the same layout (chips go in the middle and have 5 connected holes off each pin) but this limits your ability to shrink your prototype. The kind I like is the single hole per pad. Yes you have to bridge the pads with solder. I don't know why connecting two conductors with solder shocks you so much ;D

For off board connections just use whatever works, female sockets are good, or just soldering the wire directly to the board

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I do a lot of stuff on strip board but also consider single hole board. You can make the connections here by bending the component wires to where you want them or adding extra insulated wires. You can even make the layout look a lot like the schematic if you want. Also single hole board also makes it easer to use the odd surface mount component.

For a lot of wiring up I use the "Vero wiring system" (it might be called something else by now). This is a wiring pen that has a small reel of insulated wire on the back. You use this to make the interconnections and when you solder it the insulation melts only round the joints.
http://freespace.virgin.net/john.hardaker/Musatek/vero.html
I have used it for over 30 years now and is great when there is a lot of wiring.

Also have a look at some of my projects these use a mixture of non PCB techniques.
http://www.thebox.myzen.co.uk/Hardware/

Connectors as you say are almost infinite. Try and stick with those on a 0.1" pitch to make things easer. For lots of connections look at IDC (insulation displacement connectors) connectors and ribbon cables.

4

For old time sake, I will mention wire wrapping.

I've even seen computers that will built with wire wrap.

I haven't seen too many recently, so you might have trouble landing the necessary parts and equipment.

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This is partly because I have a lot of ethernet cables around, and partly because some of the connections need to go a meter or more in distance and the twisted pair wires in Cat5 cables are good at preventing signal noise, I understand.

Depends on what sort of signals are going through the cable. Differential signaling--like ethernet, RS485/DMX, USB--gets the biggest help (and has other advantages in long distance transmission), but occupies two conductors per signal.

On the roll-your own header route, it seems very tedious to solder lots of wires to the male header pins; at least I haven't found a good way to clamp the wire to the pin while using my other two hands for the soldering iron and solder.

It helps if you tin the wire and header pins first, with a bit of a blob on one or the other. Then you can hold the headers in a 'third hand' or even stick them into a breadboard, use one hand to hold the wire to the proper pin, and just touch the iron to the wire+pin to reflow the solder.

For a lot of wiring up I use the "Vero wiring system" (it might be called something else by now). This is a wiring pen that has a small reel of insulated wire on the back. You use this to make the interconnections and when you solder it the insulation melts only round the joints.
http://freespace.virgin.net/john.hardaker/Musatek/vero.html
I have used it for over 30 years now and is great when there is a lot of wiring.

That looks very cool! I wonder if there's a reasonable US distributor.

6

Lots of good advice here.
Thanks, all.