[sdiy] PCB size for euro-rack format

[Laurie Biddulph]

There is very little weight on the boards and most of the force is exerted 
on the jacks which in your case are not fitted to the pcb anyway. The 
brackets, therefore need only to carry a few dozen grams of weight and to 
take any flexing caused by the power cable connection when the module is 
removed or inserted.

Of course, if your board has a VERY heavy object like a transformer on it 
then you will probably find that not even the 3 holes on the mounting side 
will be enough and that the board itself would need mounting on to a large 
L-bracket.

So, 2 holes for mounting will be fine. Remember that mounting the board on 
to the bracket will require some horizontal height (unless you are providing 
a clear area on the pcb where the bracket would be mounted) and this has to 
be factored in to the panel width. So, for example, if mounting the board 
behind a column of jacks or toggle switches, you will probably find that the 
pcb will be sitting somewhere central to that column and so you may have to 
consider any tall components such as electrolytics and where they will be 
extending in to.

This bracket approach was used on the ETI 4600, Maplin 3800/5600 synths. In 
there case, the pcb had a whole side left blank so that the pcb could be 
mounted directly on to the bracket. This results in the pcb sitting to one 
side of the column of components based on the dimension of the bracket. This 
is quite wasteful in pcb real estate so you may need to consider just 
defining a small area around the 2 fixing points to allow for a small spacer 
to be inserted between the pcb and bracket. This will maximum the available 
pcb space for circuitry but reduce the maximum height of components by the 
height of the spacer. Given that a good thru-hole solder connection should 
be between 1mm and 2mm below the pcb, you will need to be looking at a 
minimum of a 3, probably, 4mm spacer.

Best Regards

(Mr) Laurie Biddulph
Phone: +61 (0)2 4340 0938
Mobile: 0400 257 645

Elby Designs
ABN: 70 022 727 605
http://www.elby-designs.com

This e-mail and any files transmitted with it are confidential and intended 
for the addressee only.
If you are not the addressee you may not copy, forward, disclose or 
otherwise use it, or any part of it, in any form whatsoever. If you have 
received this e-mail in error please notify the sender and ensure that all 
copies of this e-mail and any files transmitted with it are deleted.
Any views or opinions represented in this e-mail are solely those of the 
author and do not necessarily represent those of Elby Designs.
Although this e-mail and its attachments have been scanned for the presence 
of computer viruses, Elby Designs will not be liable for any losses as a 
result of any viruses being passed on.

Please consider the environment before printing this email

----- Original Message ----- 
From: "Seb Francis" <seb at burnit.co.uk>
To: "Synth DIY" <synth-diy at dropmix.xs4all.nl>
Sent: Sunday, November 30, 2008 8:49 AM
Subject: Re: [sdiy] PCB size for euro-rack format


> Interesting to see that all these metal brackets fix to the PCB with only 
> 2 bolts.  I guess this must be strong enough for a vertically mounted 
> board.  So I reckon I'll just have 4 holes (1 in each corner), not 6. 
> Worth saving these 2 - that's about 12 resistors worth of space.
>
> Seb
>
>
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>