[sdiy] prototype boarding (help?) and homemade pcbs.

[René Schmitz]

Hi Cole,

Cole Groff wrote:
> would you guys happen to have any suggestions on how to transfer
> circuit schematics to a prototype-board like this?  i've just made a
> big mess trying to make things fit and work things out.  but, it seems
> like there should be some simple guildlines to make it easier.

Don't try to cram that circuit into too little space. And for all but 
the simplest circuits use pad per hole, not stripboard.

I would suggest following the schematic roughly. Start from the left and 
go to the right. If you want to place components first and then do the 
connections you need to estimate how far the active components 
(tranistors, ICs) need to be apart from each other. (Depending on how 
much resistors and caps are between them.) Then leave some slack.

I never use any paper in the process, I do that all in my head, but 
maybe thats just me. :-P
It could help using a printout of the schematic and cross out the 
connections you already made. Really as soon as you have done one.
Do the more localised connections first, run the "loops" of that "graph" 
first, and follow the circuit in a functional way, e.g. in that ADSR, 
make that three transistor circuit, exept for the connections to the 
7555, then when that is finished, go ahead to that 7555 and so on.
(And while on the subject on that third transistor there ought to be 
added a diode in reverse over B-E, just like on the first one.)
In the end you don't have the most compact realisation, but one that 
relatively closely resembles the way it is drawn on the schematic. This 
will aid in troubleshooting. Also when you do it this way you don't get 
into trouble with space since you don't need to put big components 
between already finished parts later.

There are a couple different ways one actually makes the connections:
All wireing on the solderside (using mostly cut pieces of the resistor 
wires). This would end up much like a single sided layout. For 
connections between adjacent pads, you can use blobs of solder.

You can combine this with the other technique: flying wires on top, this 
is especially handy for very dense connections (busses on digital 
circuits for example) which aren't really possible on a strictly single 
sided layout.

Here you might choose to put the pots and jacks on one side of the 
board, and run flying wires to the actual points where they would be 
needed. Even if you don't want to put the pots there, it will be nicer 
if all external connections are just on the edge of the board and not 
scattered everywhere.

> also, i've been thinking of making my own pcbs at home.  this would
> solve the prototype-board problem.  but, i would need a macintosh
> program that would let me layout the schematic, then have the program
> translate the schematic to a pcb layout.  is this possible on a mac?

Well fully automatic layout (autorouter) tends to get ugly (and you need 
to specify a lot of rules to avoid things like a sensitive input running 
right next to a clock line and so on). I think it is still mostly used 
as an aid in interactive routing.

Cheers,
  René

-- 
uzs159 at uni-bonn.de
http://www.uni-bonn.de/~uzs159