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How to use Prototype board?

D

Daniel Beer

Jan 1, 1970
0
Heya,
I recently got a prototype board for an AVR project I want to make. The
board has a green soldermask (?) and on the back there is a small metal pad
around each hole to recieve solder, none of which are connected (no busses).
There are also VCC and Ground busses around the sides. You can check it out
at http://www.olimex.com/dev/avr-p20b.html.
My question is how would I use this to make a circuit? How do I connect
individual components that I solder on the board to each other? Should I
solder wires onto the board too, or should I solder the pads on the back
together? Thank you

- Daniel
 
H

happyhobit

Jan 1, 1970
0
Hi Daniel,

I use wire-wrap wire (#30) for point to point wiring.

Jay
 
D

Daniel Beer

Jan 1, 1970
0
How would I do this? Solder the components to the board and leave the leads
sticking out past the
board?

- Daniel
 
H

happyhobit

Jan 1, 1970
0
Yes, same as soldering any components to a PC board. (Other then SMT)

I don't wrap the wire to the device leads, just hook the stripped wire
around the lead at the circuit board and re-flow the solder. If you're using
a high current device you might use a larger wire but for a hundred ma 30
gage works fine.


Jay
 
R

R. Steve Walz

Jan 1, 1970
0
Daniel said:
Heya,
I recently got a prototype board for an AVR project I want to make. The
board has a green soldermask (?) and on the back there is a small metal pad
around each hole to recieve solder, none of which are connected (no busses).
There are also VCC and Ground busses around the sides. You can check it out
at http://www.olimex.com/dev/avr-p20b.html.
My question is how would I use this to make a circuit? How do I connect
individual components that I solder on the board to each other? Should I
solder wires onto the board too, or should I solder the pads on the back
together? Thank you

- Daniel
-------------
Are you the kind of kid who had to be shown how to use a toilet?

Nobody ever showed ME any "proper" way to use hole-per-pad protoboard!!
There isn't any, use your brain!

I have noticed there are two kinds of people on "how-to" newsgroups,
the ones answering questions, and the ones asking them.

And from my more than ten years experience here and twenty five years
in electronics, it has become obvious to me that the ones answering
all the questions never even HAD to ask any, they went and found out
the best way FOR THEMSELVES, BY THEIR *OWN* EFFORTS AND EXPERIMENTS!
And Thank GOD I'm one of them!

I don't know where all the other kind come from, but I wish to hell
that they'd stop! It's like someone REALLY screwed them up so that
now they won't even trust their own imagination to TRY things before
asking! The heart of the pride of the Duffer, the "Hacker", is that
he doesn't EVER read the manual first, he has taken pains of long effort
and experience with devices so as to develop a mind that TELLS him how
human devices usually work so that he doesn't HAVE to read the manual,
he could have WRITTEN IT!

He's the kind who always took everything apart to find out how it
worked, and usually became the first in his family or circle of
friends to understand how to put it back together! To be one someday
there is NO OTHER PATH one can take other than to resolve to begin
doing it RIGHT NOW! That means you have to resolve to figure out how
everything works, and to keep all your notes in your head, and to be
relentless in finding it all out!!

-Steve
 
D

Daniel Beer

Jan 1, 1970
0
Thank you. I think i'll try that. : )

- Daniel

happyhobit said:
Yes, same as soldering any components to a PC board. (Other then SMT)

I don't wrap the wire to the device leads, just hook the stripped wire
around the lead at the circuit board and re-flow the solder. If you're using
a high current device you might use a larger wire but for a hundred ma 30
gage works fine.


Jay


-------------------------------------------------------------------------- --
"I'm pullin' for you; we're all in this together", Red Green
-------------------------------------------------------------------------- --
.
.
Should
 
H

happyhobit

Jan 1, 1970
0
Steve, you're being rude again.

I think that there are three kinds of people here, the ones that ask, the
ones that answer and the ones that complain.

If no one asks, we're all out of a job.

Jay

P.S. I WAS shown how to use a toilet, I was potty trained, weren't you?
 
C

C Rose

Jan 1, 1970
0
Hi Daniel

From your description of the board it sounds like you would need to
use "wire wrapping". Basically, this involves soldering the component
pins to the board and then making the links using thin pieces of wire
which you wrap around the pins and then solder.

This is, in my experience, a terrible way to put together a circuit.
I'm a pretty good solderer, and I find wire wrap really fiddly.
Further, using wire wrap it is very easy to accidentally create shorts
and it is easy to accidentally break connections. Many people use wire
wrap for prototyping, but I think this is flawed too, as making
changes to a wire wrap circuit can be difficult (especially if it is
complex).

To learn how to wire wrap, you really need someone to show you how.

I would suggest that you buy yourself a large breadboard, which is a
grid of holes into which you can insert (the uninsulated end of)
wires; the breadboard has connections between groups of these holes
(i.e. rows or columns). You can also place components into these
holes.

The advantage of using this system is that it is easy to make
connections and easy to change the circuit. It involves no soldering
and is not the least bit fiddly. (Mind you don't burn out any
components though, as this will melt the breadboard!)

Once you have verified your circuit works you can make a note of the
circuit and then use a "proper" method to create the circuit
permanently.

You will almost certainly be able to get free/cheap circuit layout
software. Use this to create a circuit and then print it out onto a
transparency. Use the UV lightbox and UV-sensitive copper clad board
(along with the developer and etching chemicals) method. This method
requires some (monetary) investment, but it is an excellent method for
making permanent circuits.

In short: avoid the wire wrap, it'll sap the life out of you!

Have fun

Chris
 
R

R. Steve Walz

Jan 1, 1970
0
happyhobit said:
Steve, you're being rude again.
------------------
Yeah, well, somebody ought to, even if one is quite enough to point
out to some poeple that they should stop asking and start DOING!

I think that there are three kinds of people here, the ones that ask, the
ones that answer and the ones that complain.

If no one asks, we're all out of a job.

Jay
 
Z

zalzon

Jan 1, 1970
0
You will almost certainly be able to get free/cheap circuit layout
software. Use this to create a circuit and then print it out onto a
transparency. Use the UV lightbox and UV-sensitive copper clad board
(along with the developer and etching chemicals) method. This method
requires some (monetary) investment, but it is an excellent method for
making permanent circuits.

I shall I'll take your advice.

Could you recommend a free circuit layout software.

Could you also elaborate on the UV method of etching?
 
C

C Rose

Jan 1, 1970
0
Step 1 in learning electronics is to solidify your theoretical
knowledge using prototyping systems such as a breadboard. I wouldn't
look into other types of circuit fabrication until you've got a decent
feel for things and are willing to spend a little cash on the right
tools.

I'm afraid I can't recommend any circuit layout software as it's been
a few years since I've done any electronic design (it's software all
the way right now...). But this looks pretty good
(http://www.expresspcb.com/). They offer to make the thing for you for
a fee, but this takes away all the fun :)

I can tell you about the "UV method" of circuit fabrication, though.

Once you have your fancy new gizmotron designed and prototyped, you'll
want to make the circuit a little more permanent (and reliable). I
recommend the following method. It's probably the most work and
requires the largest monetary investment (mainly set-up costs), but it
will produce the best end results.

You need an electronic CAD program (such as the above), and use it to
layout the physical design (rather than schematic). Some systems allow
you to input your schematic and the software will produce a layout for
you, but you will need to edit this to meet any mechanical
constraints.

Once you are happy with the design, you print it onto a transparency
at 1:1 scale. Then, you get some photo-resist copper-clad board. This
is a board made from either Synthetic Resin Bonded Paper (SRBP, cheap,
OK though) or fibreglass (more expensive, overkill for home
hobbyists). One side of the board is covered with a thin layer of
copper. This, in turn, is covered by a layer of photosensitive film.
When you buy it, this will be covered by black sticky plastic (to stop
ambient light from reacting with the photo-resist layer).

What you do is cut a piece of the board to the size of your circuit.
You then place the transparency onto a UV lightbox and place the piece
of board on top (having removed the plastic!), photo-resist side down.
You then close the lid and expose the board for however long (2
minutes or so -- see the instructions with the copper-clad board and
your UV box). So, what happens is the UV light interacts with the
board where your circuit tracks are not (because these areas are
shielded by the ink on the transparency).

You then place the board in some developer solution for however long.
This removes the photoresist where it was exposed to the UV light, and
leaves photoresist where your circuit tracks are. You then wash the
board in water and place the board into the etching solution (ferric
chloride). This removes the copper under the remaining photoresist
leaving your circuit behind. You then wash the board, dry it and rub
the photoresist off with some wire wool.

The above process takes a few attempts to get right when you are
beginning, as there are a few ways to go wrong: you might get the
transparency the wrong way up (doh!), under- or over-expose the board
(doh!), under- or over-develop the photoresist layer (doh!), or under-
or over-etch the board. After you've done about 10, you'll be a dab
hand, though. And it's fun: it's like home photography, but for geeks
(no darkroom required!).

You now have a PCB with no components on it. You need to drill the
holes for your components using a fine drill bit (1mm-ish). You then
populate the board with your components (they sit on the non-copper
side) and solder them in place. Then you power up and hopefully all's
well.

When you get really good, you can make double-sided boards for those
really complex designs!

So, what's this all cost, you ask?

You'll need (prices in British Sterling, USD total given below):

Copper-clad board with photoresist layer £2
Transparency (suitable for laser or inkjet printers) (cheap)
Printer (I'll assume you have one)
UV light box £100
Developer solution £8
Etching solution (ferric chloride) £5
*Plastic* tongs (the chemicals are nasty!) (cheap)
Two plastic trays (to hold the solutions) £3 each
Small pedestal drill*
Soldering Iron £20
Wire wool (cheap)
Solder £15
Components (cheap, depending)
Multimeter £15

Total: <£150 (US$250)

* A drill like this (http://www.dremel.com/productdisplay/att_template.asp?SKU=212&Color=99CCFF),
but you can get cheap ones. Don't try drilling without a pedestal!

Take a look at this (UK-centric) page for some of the things I'm
talking about (http://www.maplin.co.uk/Search/resu...el=1&Menu=17&Name=PCB and Circuit Development)

Once you really get into things you can get a decent power supply and
then some kind of oscilloscope...

Hope this helps

Chris
 
Z

zalzon

Jan 1, 1970
0
Wow that's a lot of useful information Chris. Thank you.

I built a simple 555 timer, my first circuit ever. I built it on a
breadboard. There are lots of wires going here and there. I was
thinking the next step would be to etch a board and transfer all the
stuff onto there.

Someone told me it would be better to do it on a vero board instead
and try etching sometime later. I heard about wire wrapping although
you advise against it and from the sounds of it, it sounds rather
messy wrapping wires here and there.

The process you described is quite involved with many places along the
way to make mistakes. I have most of the items you listed except the
various solutions, the copper board and the (expensive) UV box.

I wish i could watch someone do it. I think I could learn a whole lot
quicker and save some money on having to experiment.
 
D

DocBrown

Jan 1, 1970
0
Daniel Beer said:
Thank you. I think i'll try that. : )

- Daniel
Hi Daniel,

If you are interested in a very simple to use system of prototyping,
take a look at http://www.onepasinc.com . Be sure to look at the
sample
circuits page, there are some very good examples of how to place
components.
They put a schematic up right next to the proto drawing so you can
follow back and forth to see how it all goes together.

Best of luck,

Doc
 
D

DocBrown

Jan 1, 1970
0
Hi Daniel,

I think one of the simplest and most effective methods you can find
for your circuit would be at http://www.onepasinc.com

Check out the "Sample Circuits" page, as they put a schematic up next
to the layout on the board so you can go back and forth between them
and see how they did it.

Best of luck, Doc
 
C

C Rose

Jan 1, 1970
0
Hi

Veroboard is fine. I was forgetting that :)

Using veroboard is pretty easy. All you do is break the tracks where
required using a drill bit or a special tool. Then you just solder
your components in place.

Veroboard is great for learning to solder; just buy some resistors and
solder loads of them onto a sheet of veroboard; you'll soon be an
expert! That's how I learned to solder.

The problems with veroboard are similar to wirewrap: it's hard to do a
complex circuit, and you end up with a mass of wires. I'd go for
veroboard over wire wrap though!

It certainly helps if you can watch someone make a PCB using the UV
method; but I reckon that once you've done some circuit design and
verification using a breadboard and designed the physical circuit
using some ECAD software, you'll be pretty set to be able to figure
out how to etch your own PCB. It *is* more expensive, but by the time
you get to the stage of wanting to etch your own PCBs, you'll probably
be prepared to spend that sort of money.

In terms of the cost of the UV method, most of these are in the
set-up; once you have the UV box etc., the cost of the boards etc. is
actually pretty low.

Chris
 
J

JeffM

Jan 1, 1970
0
To learn how to wire wrap, you really need someone to show you how.
In short: avoid the wire wrap, it'll sap the life out of you!
Chris (C Rose)

Wirewrapping can make mods/updates/fixes easy
on prototype/quasi-production stuff
but the ratsnest of little wires can be daunting
and, as had been said, those little suckers break easily.

The trick to making life easy is to do buses / multi-point chains properly.

Imagine that wire W breaks in each of these assemblies.
How many wires have to be removed from each example
to pull and replace the broken wire?
(Assume that the stub at the top is too short for the minimum required turns.)

| | | | | | | |
@\ @\ @\ @\ @\ @\ @\ @\
@ \ @ \ @ \ @ \ @ \ @ \ @ \ @ \
| \ | \ | \ | \ | \ | \ | \ |
@ \ @ \ @ \ @ \ @ \ @ \ @ \ @
\@ \@ \@ \@ \@ \@ \@ \@

W
| | | | | | | |
[email protected] @[email protected] @[email protected] @[email protected] @--
@ @ @ @ @ @ @ @
| | | | | | | |
@ @ @ @ @ @ @ @
@[email protected] @[email protected] @[email protected] @[email protected]


A common technique is to use a different color for each layer. e.g.,
supply1 == red
supply2 == orange
gnd == black
Bottom layer == blue
2nd layer == yellow

This makes inspection/troubleshooting easier.
e.g., Blue wire from bottom to top == OK;
yellow wire on bottom of 2-wire stack == wrong;
yellow wire from bottom to bottom == wrong.
 
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