Prototype Construction Tips

[BillO]

The idea behind this thread is for us to share various prototype construction tips that have allowed us to work better. They could be solderless breadboard techniques, proto-PCB techniques (those designed for DIP packages), strip board techniques, wire wrapping, etc.

Please share!

[BillO]

Let me start this off with a tip that I've used with DIP type proto boards. I buy IC sockets that have an ample slot in them between the pins so that I can mount bypass capacitors midway between the Vcc and Gnd pins.

[floobydust]

Good thread... I've also used the same technique for bypass caps under the sockets, both in prototype boards and in final PCBs... saving space is saving space, plus it also keeps connections short.

Another thing I've done for prototyping is to swap out a working I/O chip and build up a prototype for another I/O chip on a small board that plugs into the existing I/O socket. I did this to get a NXP UART working. A small board to hold the SCC2691, a 74HC00, XTAL and a few caps that plugged into the 40-pin DIP socket. I just used a separate FTDI USB-UART interface to get another console port.

[GARTHWILSON]

Good topic idea! My 6502 primer page on wire-wrap questions and doubts answered is at http://wilsonminesco.com/6502primer/WireWrap.html .

[Dr Jefyll]

There are several prototyping tips in my thread, TTC: a 65xx sandbox *not* built on a breadboard.

See also this post, which mentions two different ways to adapt IC sockets for wire-wrap. The technique shown in the first photo works with a PLCC socket or an ordinary DIP socket. The pins are harvested from inexpensive header strips. Notice the proto-board has plate-through holes, which, for mechanical reasons, I consider mandatory with this trick.

The technique in the second photo uses machined pins. For a PLCC socket it makes sense but, for a DIP socket, not so much. Again, the proto-board has plate-through holes (although it's perhaps slightly less critical in this case).

[cbmeeks]

I love this thread!

And here I thought I was being smart with my LCD development. I propped my breadboard up at ~60 degrees and support the bottom with some Blue-tact. Makes it much easier to glance over instead of having to look down at that screen.

BillO wrote:

Let me start this off with a tip that I've used with DIP type proto boards. I buy IC sockets that have an ample slot in them between the pins so that I can mount bypass capacitors midway between the Vcc and Gnd pins.

sockncap.jpg

What kind of wire is that?? I find WW wire too thin to prototype for soldering. Seems to break really easily.

My breadboard wire seems too thick (I think it's 22AWG IIRC...maybe thicker). When I solder it down, it's so stiff that I find it hard to move them around for other wires. That wire you're using looks to be the perfect diameter.

[floobydust]

For many years I used standard WW wire for point-to-point wiring on perfboard circuits. I would simply strip about an inch (or more depending on how many pins to solder it to) of insulation from the end and start soldering, and then use a WW wire stripper to continue slicing the insulation and sliding it down the wire as I went from pin to pin. I never cut the wires except for the two ends. I wired up dozens of memory expansion boards this way... much quicker than the usual wire-wrap process as well.

Unfortunately I don't have any pics with me... when I get back to Boynton I can share some pics of an old Vic-20 memory expansion board I made this way back in the mid-80's.

[cbmeeks]

floobydust wrote:

For many years I used standard WW wire for point-to-point wiring on perfboard circuits. I would simply strip about an inch (or more depending on how many pins to solder it to) of insulation from the end and start soldering, and then use a WW wire stripper to continue slicing the insulation and sliding it down the wire as I went from pin to pin. I never cut the wires except for the two ends. I wired up dozens of memory expansion boards this way... much quicker than the usual wire-wrap process as well.

Unfortunately I don't have any pics with me... when I get back to Boynton I can share some pics of an old Vic-20 memory expansion board I made this way back in the mid-80's.

Yes, I would be very interested in seeing that.

I've tried to do it like Ben Heck does with no luck. Basically, just soldering through the insulation without stripping. One long wire for multiple connections without cutting or stripping. Sounds like an excellent idea but in my experiences, the wire either breaks, pops off or the insulation melts so much that too much wire is exposed.

[BillO]

cbmeeks wrote:

What kind of wire is that?? I find WW wire too thin to prototype for soldering. Seems to break really easily.

It's AWG30 WW wire. I've used it for so long I guess I have gotten used to handling it.

[cbmeeks]

I have a bunch of AWG30 in different colors. I'm usually pretty good at handling this stuff but I think I just have some poor quality wire. I got all of it from eBay. When I compare my WW to what I've seen online, the ones online just look thicker. I mean mine seems like it could be used for PCB traces.

Do you happen to remember where you got it?

[Martin A]

I use 30 awg Kynar for point to point, there's almost no shrinkage. I melt 2mm or so with the iron tip for each joint.

Most of my stock is either https://www.mouser.co.uk/ProductDetail/ ... ziThR3k%3d or https://uk.rs-online.com/web/p/hookup-e ... e/2094811/

It works well on long traces. Some of the data bus connections on this board (yellow) have 10 or so loops going across the board in a single piece. The address bus in blue is almost as long.

ATX size board Point to point wired

BTW the power links use much larger 2A PVC coated wire and shrinking insulation was a constant problem.

[BillO]

cbmeeks wrote:

Do you happen to remember where you got it?

Over time some I've gotten of eBay and some of Amazon. I make sure they advertise the insulation as Kynar as that is what I always used back when I did to actual WW. Go with what you know. Martin is right in that the insulation does not shrink. That orange stuff came on a 100 meter roll that I got of Amazon, but I have had good luck with eBay stuff too. I have some I got of eBay a while back (maybe 2 years ago) and have not tried yet. I'll have a look at it and see if it's any good.

[cbmeeks]

Looking on mine, Kynar is nowhere to be found. So I must have some cheap junk.

[Floopy]

I should have thought about putting components under the sockets!
Looking at the design I recently made I'm starting to realize how badly designed it is. It works, but I could have done a better job at the routing. I've noticed that on professional boards, on one side the traces run horizontal and the other vertical. You probably all know this already.

[Mike Naberezny]

Martin A wrote:

I use 30 awg Kynar for point to point, there's almost no shrinkage. I melt 2mm or so with the iron tip for each joint.

I am also using point-to-point with 30 AWG. I always strip the ends. I hold the wire with a pair of needle nose pliers. The pliers I use have flat jaws so they don't score or cut the insulation. While holding the wire, I strip the end with a sharp pair of small wire cutters. Sometimes I have a bus wire that passes through several connections and I'll melt the inner connections. Below are a couple of photos of a board that I built recently.

Fujitsu F2MC-8L SBC (Top)

Fujtisu F2MC-8L SBC (Bottom)