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pcb's

Started by mop-head, November 18, 2006, 04:07:07 AM

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mop-head

I have seen quite a few people on this site talking about pcb's. :o I think these are some sort of circuit board? Well, i was wondering, do i really need to do a pcb to do a progect, and if i do, how would i go about doing it?

teemuk

#1
Correct. PCB=Printed Circuit Board. You donĀ“t really need one for projects but in my opinion using a printed circuit board can extensively ease the building process and make the component layout and wiring much more compact.

There are many alternatives for PCB, for example veroboards, stripboards and point-to-point (PTP) wiring, which means soldering component leads and wires together using no circuit boards at all. While the amount of components in your project grows higher the more likely you will wish to use a printed circuit board. Some small circuits you can simply PTP. After building even a moderate size circuit on a veroboard you will notice that the process (and finding faults) would have been much easier if you have made a PCB.

Anyway, none of the methods - not even making a PCB - will save you from the very important aspect, which is designing a good component layout - unless you buy the PCB of course. In my opinion, designing layout for PCB is easier than layouting a vero- or stripboard since the PCB allows routing the traces (which are the board's counterpart for wires) any way you like. This also makes the boards much more compact. In vero- and stripboards you have to use the existing traces. There are also other important factors for the design, such as using correct trace width (you would not use a thin wire for high currents either, would you) and ground current routing issues to name a few.  Etching the PCB is actually the easiest part in the whole process of making it.

The actual process following the design part isn't very difficult but you will need tools for it: The minimum list is some acid (ferrocloride) to etch the copper, an etching tank and a very small drill. It also helps if the acid is heated during the etching process so you will need some kind of device for that as well.

Depending on a PCB, the traces can either be drawn straight to the (polished) copper surface with a permanent marker pen or the copper is protected by light sensitive material. In later case transparent plastic sheets and Xerox machine will prove useful. Unfortunately, you also need a special lamp for the process and another kind of acid to etch off the "exposured" surface and reveal the copper underneath it so that you can etch it. The internet is full of information about PCB making, this was just a mere scratch.

joecool85

Good explaination of PCBs teemuk. 

Veroboard (aka strip board) is basically a piece of perfboard with copper lines running down the bottom side of it.  You can connect these lines with components to make a circuit.

These pictures should help, click them to enlarge.
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

teemuk

Very nice visual example.

To further comment, I'd say either a CAD or a customized PCB design software, such as Eagle or ExpressPCB, would be quite useful. ExpressPCB is freeware and quite easy to use but will not allow exporting the boards in a printable format. I still use it and plainly make a screencapture out of the boards, which I then scale for printing. In the most simple boards I use the printed sheet only as a model for drilling the holes to correct places after which I draw the traces with a marker pen. Works extremely well. I guess you could do this even with Windows Paint since one can always bend the legs of most components for little tolerance. Multilegged components (opamps etc) can be quite troublesome. Editing the layout with a special software is much more easier though.

There is also design software for stripboards like StripBoard Designer (surprise). For this purpose, however, I prefer more "sophisticated" methods like squared paper or Windows Paint. Runoffgroove.com site has pictures of perfboard layouts that can help a lot. As far as I know, all of the projects on that site utilize only perfboards. All software mentioned (Except Paint) can be found with google.

mop-head

thanxs for the explination teemuk and joecool85!  :)

Crystallas

If you really want to learn and experiment. I suggest you pickup a decent breadboard for testing. Its not very expensive, but it will help you test out a lot of ideas and designs with minimum soldering.

lurkalot

Quote from: Crystallas on December 04, 2006, 02:57:18 PM
If you really want to learn and experiment. I suggest you pickup a decent breadboard for testing. Its not very expensive, but it will help you test out a lot of ideas and designs with minimum soldering.

Sorry to drag up an old thread.  I went searching on google for breadboards, and didn't quite get the result I was hoping for at first.  8|

But found a few after a bit of digging.  There does seem to be quite a few variants of the breadboards, does it matter what one I go for?  The prices seem to jump around quite a bit too. 

J M Fahey

Get the breadboard-of-the-day at radio shack or equivalent and start experimenting.
If it becomes small, buy another, they almost always have some kind of "ears" to stick 2 or 3 together.
Worst case, glue them to a piece of plywood or something.
You should do this anyway so you also fix there a strip of aluminum (or plastic)with various holes for jacks, pots , switches and Leds.
You can experiment a lot with that.

lurkalot

Thanks for the info. 

Not sure we have a radio shack in the UK?  at least I've not seen one, we have Maplins which is similar I believe. 

J M Fahey

Don't insult it ... Maplins is 1000 times better  :tu:
Plus UK is the cradle of Veroboard, which is the next logical step.
In fact, in the UK in the old days, it used to exist an incredible product, called "The Blob".
It was a pack with one proprietary Protoboard and 3 Veroboard style perforated boards with the exact same layout, numbering, etc. of the protoboard, so once you are happy with a proto design, you transfer it *exactly as-is* to one of the solder boards.
*Excellent* to avoid mistakes !!!
This is the American version, but the original idea is British and available there:
https://www.adafruit.com/products/571

Roly

Making PCB's - one of many such discussions, mainly concerned with the many various ways of homebrewing stomp box PCB's.

http://www.guitargear.net.au/discussion/index.php/topic,32366.0.html

Radio Shack = Tandy (woz here in Oz 'til they were eaten by Dick Smith who were eaten by a big supermarket chain, and now all run into the ground and ruin. (sigh))  I go to Jaycar and Altronics here and if I was in the UK I guess I'd go to Maplin.

When I etch, rare these days, I still pop the layout points onto the laminate then connect the dots with a waterproof felt tip marker.  I'm slightly interested in trying the vinegar, salt, and hydrogen peroxide etchant just to compare with ferric chloride 'coz I can make up the former from the local supermarket.

I'll confess that I really don't like protoboards after trying to tute someone doing a D/A converter project who spent most of the time finding bad connections; however saw an idea, on Hackaday I think, where someone had made a PCB layout that matched his protoboard, and he put this down first (which looks like Adafruit picked up).  Once the design was complete he held all the components and links in place with a sponge, unplugged the whole lot from the protoboard, and soldered all the wires to the matching PCB.  I thought this was a very cunning way of transferring the proto to a final PCB without introducing a whole bunch of errors along the way.  But I still don't like protoboards.  I use a lot of Vero stripboard for small stuff, but my favorite is dab or donut board where you have more freedom of layout and simply wire point to point.

I spent too many years at the drafting board using Bishop Graphics sticky donuts and tape, so my favorite layout s/w is still EasyTrax, now "abandonware".  I do a layout, print it out, cut and glue to stripboard topside, then assemble through, so it winds up like an component side overprint.  I've found that this has made actual assembly a no-brainer (important with creeping senility  :duh ), reduced my error rate to zero, and is self-documenting.  It's an area were everyone seems to have personal favorites.  my2cents.
If you say theory and practice don't agree you haven't applied enough theory.

J M Fahey

Make it 4 cents, I *also* use and love Easytrax.

Ok, ok, rise the bet to 6 cents: I use even more (and warmly recommend) Protel Autotrax 1.61 (the original Pro design software of which Easytrax is the "free sample").
Also abandonware, like Easytrax on steroids, can do things not even Eagle or others can.
Definitely not with such ease or without paying a Ton.
Did I mention *Free*, *legal*, *unlimited* pins, *eight* copper layers +4 or 6 extra (2 silkscreens, "Board", etc.) , 32" x32" board size limit (no kidding, 10 feet by 10 feet boards),  etc.
Did I mention they are Australian products?  :duh

Roly

I've used it for a lot of other things besides PCB layout, a building, and many speaker cab builds, in fact I'm doing a J-Scoop in it ATM, but I've never hit the limits - can't be trying hard enough eh?   ;)

And yes, Tasmania is nominally part of Australia, 'tho some of the denizens don't seem to think so.

{Since Canberra just excised the mainland from our immigration zone some of us are wondering if Australia is still part of Australia.  :o }
If you say theory and practice don't agree you haven't applied enough theory.