EEVblog Electronics Community Forum
General => General Technical Chat => Topic started by: beaker353 on July 22, 2012, 08:27:19 am
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I’m in the process of building a custom prototyping station. It will hold four of the large 3M breadboard units side by side and a number of binding posts for power connections all mounted to a single large 12’ish by 12’ish inch base. I am trying to decide what material I should use for my base. I’m figuring that a metal of some type would be the best, but I’m having trouble determining what metal I should go for. I deal with a lot of mixed analog (mostly audio frequency) and digital circuitry so I’m thinking that having the entire base as one huge ground plane (tied to ground of course) would be a good way to keep everything quiet and isolated. The idea being that any lines of flux from the above circuits will induce current within the metal and then get dumped to ground instead of the flux lines spreading to other parts of the breadboard. From my day job working with professional audio gear I have learned the true power of good shielding and what can happen when a manufacturer goes cheap and things sound like crap.
First question, is my fundamental understanding correct that a base for this station made of the right metal would convert lines of magnetic flux generated by circuits above into current in the base and be dumped to ground to reduce that flux from inducing current elsewhere in the breadboards? Secondly, would I need to use a ferrous metal for this to be effective or would a non-ferrous metal like aluminum do just as well. I know enough to know that I don’t know enough...
-EM
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I don't think you have to worry about magnetism. I'd say something like aluminium would work fine. Lightweight and easy to cut and bend.
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I would suggest a thick plastic over a steel base. This would reduce the capacitance from the breadboard to the ground plane ( good in any case) and the steel underplate will provide some magnetic and lossy RF blocking. The plastic will most likely be acrylic ( easy to buy in thick ca 10mm sheets) and will need to be bonded to the steel with an epoxy resin after sanding both surfaces clean and washing them with a oil removing solvent to promote adhesion. Remember to paint the steel sheet underside afterwards with a good metal paint ( Hammerite is pretty good for this) and glue a rubber backing to it after the paint is cured to keep it stable.