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JAW enclosure

phoenix70 - 30/9/08 at 08:19 PM

Hi Guys,

Has anyone found a suitable box to fit the JAW electronics or the display. Just about to go hunting, but thought I'd see if anyone had already found one.

Ta

Scott

adithorp - 30/9/08 at 08:28 PM

I was going to have a look in Maplins for one.

I was wondering what to do about the heat sink. It being enclosed can't be good, can it?

adrian

big_wasa - 30/9/08 at 08:41 PM

I am still looking.

Lars - 30/9/08 at 08:44 PM

I have a small black project box from maplins.

I cut two holes on opposite sides of the heat sink and fitted a small fan on one and a finger guard on the other.

RichardK - 30/9/08 at 08:46 PM

I got mine from Maplins

Loads more pictures in my gallery (link below) and I did a pick list of everything I bought on the jaw website LINKY

P.S If you get an ali box don't ground the box and ground the heatsink! Don't ask how I know!!

Cheers

Rich

David Jenkins - 30/9/08 at 09:22 PM

I used a Maplin box, with a 12v - 14v Maplin fan sucking air past the regulators. Unfortunately I don't know the Maplin codes, but the fan should be easy to find.

When I turn it on with the engine off the air coming out is warm-ish. When the engine's running the air coming out is stone cold.

martyn_16v - 1/10/08 at 08:31 AM

Wouldn't it be better to fit mica insulators to whatever is attached to the heatsink to electrically isolate it? It sounds like a pretty poor design flaw to have the heatsink 'live'

MikeRJ - 1/10/08 at 11:22 AM

quote:
Originally posted by martyn_16v
Wouldn't it be better to fit mica insulators to whatever is attached to the heatsink to electrically isolate it? It sounds like a pretty poor design flaw to have the heatsink 'live'

In terms of JAW design flaws that one ranks pretty close to the bottom of the pile. Having reverse engineered the schematic, I just I hope the designer knows a little more about software than circuit and PCB design.

David Jenkins - 1/10/08 at 11:28 AM

Funny you should mention that... never get into a situation where you have to unsolder a component - it is very likely that the pad(s) will lift off the board. The PCB tracks are far too thin, and the pads are unnecessarily small for most components (although there's little choice around ICs, the rest of the board could have been a lot more 'generous' ).

I use 2 products in my car that have been supplied by what could be called 'small enterprises' - Megajolt and JAW. The 2 are chalk and cheese, as far as I'm concerned: The MJ PCB is well designed and made, and the product works well without much trouble - the JAW is flakey, frail and generally looks like it was designed by an amateur. This is only a limited whinge though, as the JAW is cheap, and it did what I required when setting up my bike carbs. I can live with the shortcomings as it isn't a permanent fixture on my car.

[Edited on 1/10/08 by David Jenkins]

Lars - 1/10/08 at 03:34 PM

If anyone needs a small fan and finger guard for their box I have a spare 50mmx50mm fan and 60mm finger guard (from Maplins item numbers JU23 and RG07H).
They are new and still with original packaging. (did not return it to Maplins quick enough)

Ł5 posted

adithorp - 3/10/08 at 01:30 PM

I've just got a box from Maplins. Its part number N59FK, multi purpose ABS box.

adrian

phoenix70 - 14/10/08 at 07:57 PM

I've now finished my JAW enclosure, just thought I'd post a few pics.

JAW Enclosure 1

JAW Enclosure 2

JAW Enclosure 3

JAW Enclosure 4

MikeRJ - 14/10/08 at 11:51 PM

You've got a few holes for the air to get in, but how does it get out?

To be honest you'd be better off putting the LM317T on short leads and bolting it to the case with a mica or silicon pad and top hat washer to isolate it.

If people are using the LED display then the 7805 should also have a heatsink on it. It gets very hot without one and will cause the voltage will drift somewhat. Since the designer decided to use this as a voltage reference this will affect the accuracy of the unit.

I have soldered numerous ceramic decoupling caps to the power rails in order to reduce the amount of noise which otherwise is horrendous, since the designer apparently decided to leave them out of the design. This has helped to stabilise the output, though it still jumps around a fair bit due to the completely inadequate PCB design and poor choice of components. If anyone has a scope handy, check the "reference" voltage on terminal "5-Yllw", a 2.5v reference that has +-2v noise on it....