Building "one"

What type of construction methods do you guys use when you are just making one of something? When I am cobbling up 4000 CMOS "logic" I use wirewrap sockets but I am making analog stuff right now with a lot of discrete componants. I have been doing point to point on perf board but it is sort of sloppy looking. Ideas?

Reply to
gfretwell
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I like the pad per hole with ground plane on one side (around each of the pads) to build analog stuff.

Figure I (I think) on this page:

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I clip each of the components at the back of the board (resist the temptation to bend leads over to make connections between adjacent pads) and use 30 AWG silver plated wire wrap wire on the back to make connections. If a component has ground on one end, I can just bend the lead at a 90 and tack it to the ground plane. Makes neat and pretty well ground shielded boards. It helps to have at least 3 colors of wire, for positive, negative supplies and signals.

Reply to
John Popelish

"Dead bug" construction. Especially at RF.

Tim.

Reply to
Tim Shoppa

Point-to-point on perf board with solder-through AWG30 magnet wire (my

5lb roll is dated 1966). Sockets on the chips. Not much bigger than a PCB.

Or just make a proto PCB and be done with it.

Best regards, Spehro Pefhany

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"it\'s the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
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Reply to
Spehro Pefhany

Until recently if the job involved an equal(ish) mix of analogue and digital bits I always used stripboard (Veroboard). If mostly digital chips then DIL style protoboard. Can (occasionally!) give reasonable appearance and performance if much care is taken with the wire links and interconnections. Don't know what others feel but to me and no matter how much care is taken in construction, the result invariably looks 'amateurish' and redolent of it being knocked up from some magazine article. For prototype demo' purposes, it's seems good enough though and customers don't mind as long as the stuff functions to their spec'. But, being a lazy bastard and with a loathing for building any kind of pre-production prototype I now build everything dead-bug style. Critical time saver is that all the groundplanes, screening, enclosures, casings, brackets and mountings are made from 0.2mm tin plated steel sheet. Interconnects by tinned copper wire. Component supports using 10Mohm resistor bodies. Like a monocoque chassis, strength builds up as components are added. This tinplate costs near nothing, can be cut to shape 'on the fly' with a pair of scissors, solders magnificently and forms a super groundplane for H.F work. Nice thing is, the result always looks shiny, very metallic and from a customers POV, "technical". john

Reply to
John Jardine.

Neat idea, much better looking than the gnarly oxidized copper-clad things in my Old Hacks drawer.

Gotta watch steel for RF ground planes, though--there's a factor of

1/sqrt(mu) in the formula for skin depth, which makes steel a superior electrical (as well as magnetic) shield but an inferior ground. For audio, 4000 CMOS, and lowish RF, it's a great idea, but I'd want copper clad above probably 20 MHz unless convinced otherwise.

Cheers,

Phil Hobbs

Reply to
Phil Hobbs

Here's the way I used to do it...

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...Jim Thompson

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|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

" When I am cobbling up 4000 CMOS "logic" I use wirewrap sockets "

Do you also wear polyester bell-bottom slacks, huge sideburns, big sunglasses and play wackachicka guitar music in the background? I mean seriously dude, it's 2006. Use a microcontroller. Build or buy one proto board, and just re-program it!

Reply to
a7yvm109gf5d1

That's actually a pretty interesting protoboard there Jim.

The power busses look a little long (not that I could do any better myself, and lord knows I saw lots of "high speed" TTL boards laid out with worse Vcc patterns in the 70's) but it's got a great ground plane on the other side.

Any memory who made that protoboard? Your own layout, Motorola, TRW maybe?

Tim.

Reply to
Tim Shoppa

I use ready-made prototyping boards. Most of them don't tie enough pins together. Here's one I haven't used yet but which seems to reveal some real thought:

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Another one that looks promising is this:

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because the job of crossing under all the ICs is done for you.

Reply to
mc

Yes. Cu my preference as well. With the stuff I do It's rare that I'm 'in the margins' and am happy to trade a tad of spec' for convenience. Last week knocked up a 50ohm pulse amplifier (74AC00 and trenchfet 2n7000). Started worrying about possible artefacts due to steel effects. Turned out needlessly. 25V pulse, 1nS rise time and nice clean top. (the steel losses probably helped!) john

Reply to
John Jardine.

mostly for analog and opamp stuff, the radio shack 276-170 perfboard, using IC sockets and 22 guage mil spec teflon soldered in. Above side of the board looks like spaghetti but its pretty reliable. 276-170 is a long linear board with 6 hole strips for each IC pin and two long ground or power traces running down the sides. If I need a lot of it, I do the prototype on the -170 and then its off to express pcb.

For VHF-450 mhz RF I build dead bug on thin double sided microwave PCB with hobbyshop copper soldered down as shielding. Above that I etch the 50 ohm traces using layout tape and paint as a resist. Since I use mostly mini-circuits parts and keep them close together, its not that bad.

Simulation is run on a acedemic version of Electronics Workbench 7 so as to be compatable with work.

Steve Roberts

Reply to
osr

Simple, fast stuff I do haywire on a sheet of copperclad. You can solder SMA connectors or whatever right to the plane. ICs get soldered standing on their ground pins, live-bug, or mount on a blob of hot-melt.

Anything more than a few parts, or with tiny parts, I lay out a 2-side board and let AP Circuits make me six or eight of them. We assign it a drawing number and archive the schematic and layout for future reference.

John

Reply to
John Larkin

I use coppeclad. You can make partitions, shields, even boxes by soldering bits together. It looks classy if you shine it first with a scotchbrite pad, but it'll tarnish over time unless you spray it with Krylon or something.

I thought *I* invented the 10-meg spacer!

John

Reply to
John Larkin

I laid it out around 1977 at OmniComp/GenRad Portable Test Products Division, to breadboard I/C designs.

(Berkeley Spice was in its infancy and device models were untrustworthy.)

It was fabricated somewhere here in Phoenix.

I've been thinking of doing a smaller version for my own "G-job" projects, since I only have a few small pieces left.

As for the power busses, this was analog chip modeling... the whole board might have drawn maybe 30mA ;-)

...Jim Thompson

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|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

If it helps you get a quantity discount, Jim, I'll go in on an order with you :-).

It looks to be the right mix of pads/buses for typical analog prototyping maybe with some light digital thrown in.

For modernization, if you could put SOIC layouts alongside/inside the DIP packages with maybe a couple of SOT-23 and 1206/603 pads thrown in otherwise empty areas then it'd be PARTICULARLY useful. I'm not generally after extreme density when prototyping... unlike some of the other examples folks here have shown!

Tim.

Reply to
Tim Shoppa

Good idea!

Me neither ;-)

I don't do PCB layout for a living... what do you folks think of ExpressPCB?

...Jim Thompson

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|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

Many years ago, and far, far away, I specified infinite ohm "1/4-W" resistors for a similar purpose (the evil twin of zero-ohm resistors. They had a single white band on them.

Best regards, Spehro Pefhany

--
"it\'s the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
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Reply to
Spehro Pefhany

I've used ExpressPCB several times over the past couple years with GREAT success. Small boards with a medium to high density of both SMT and through-hole stuff. Most of my designs were based entirely around the 2.5"x3.8" Miniboard service (combination of rapid turnaround and excellent pricing and "just right" quantity) although I've done some other odd form factors.

Those who have used truly fancy-schmancy routing packages probably are less than impressed with ExpressPCB's free software, but for me it was fine.

My overall impression is that once you get out of the onesies-twosies stage and/or into multiple square feet of board that some of the other suppliers are probably cheaper. Although I keep going back to ExpressPCB because it's just so easy. Also, the ability to send in my order at 5AM in the morning is a big win.

Tim.

Reply to
Tim Shoppa

I didn't understand that bit; how does that work then?

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John Devereux
Reply to
John Devereux

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