--- In randrdesulfatorforum@yahoogroups.com, ehsjr <ehsjr@...> wrote:
>
> The Jaycar 220 uH looks good. Can't see the RS 1000 uH,
> but if its the 1.6 A unit it will be fine.
>
> On electrolytic capacitors - you can use caps with a higher
> voltage rating than specified in any electronic circuit.
> It is not necessary in this circuit, but if you have
> difficulty getting one rated at 25V, for example, you
> can use one rated at 35V or more. The 16V caps specified
> in the original article are too low - use 25V or higher.
> 16V units work, but by going to a higher voltage rating
> you have a safety margin. And the value of C1 - 30 uF
> in the original - can be increased with no problem.

Hi Ed, thanks for the advice.

>
> That's not good for D1. 1N4004 is fine for general use, so
> having some on hand won't hurt. For this circuit, you want
> a very fast diode, such as RS 2509061830, which is a MUR2020CT.
> That is an ultrafast doide which should work very well in this
> circuit. It contains two diodes in one TO-220 package - you use
> only one of them. Connect the center leg of the MUR2020 to the
> Mosfet, and either one of the outside legs to battery (-). See
> page 6 of:
> http://www.irf.com/product-info/datasheets/data/mur2020ct.pdf
> for the schematic of the diode.

Ah, I suspected as much. Oh well, it was only $4 for 100 :-) I
daresay they'll even give me a refund if I ask. I had read that a
fast recovery diode was used but since I didn't know what that was I
took the advice I was given. I'll track down the diode you recommend,
thanks.

> You may need to adjust the traces to fit your components.
> The traces and the drilled holes have to line up with the
> actual components you use - and your L1 and L2 likely do
> not match the L1 and L2 in the drawing. Also, if you use the
> MUR2020 that's a 3 legged part and the traces don't match
> that.
>
> There is a free program that you can use to draw circuit boards:
> http://www.cadsoft.de/
>
> There are several options, regardless of what you use to
> draw the board(s) on the PC, to transfer the "artwork"
> from the PC to the blank copperclad PC board prior to
> etching. It would be a good idea to read a bit about
> making PC boards before buying the kit.
>
> Two general comments on making PC boards:
> 1) Ferric Chloride *stains*. (I'm not against it -
> I use it. But be forewarned - get it on your clothes,
> and the stain is permanent.)
> 2) You will break drill bits. You are drilling very small
> holes, with a very thin bit, which you will have to buy.
> It is not part of a "standard" drill bit set.
> The best drill bits are dental burrs, used with a Dremel
> tool. I use a drill press attachment with the Dremel
> tool, and haven't broken a bit since I started using
> that with dental burrs. Maybe you can get your dentist
> to give you some old burrs.
>
> I think you might be better off doing point to point
> wiring for your first desulfator.

You're probably right. I didn't end up buying the kit since it was
$25 and simply contained ferric chloride + 2 PCBs. Instead I got some
ferric chloride for $14 and a PCB for $3. I mainly want to make a PCB
because a) I've never done it, b) it looks like fun, and c) I read
that the desulphator may work better with nice wide traces rather than
a breadboard/prototyping board.

In my excitement at the prospect of making this, I think I may be
getting ahead of myself, so I think I will take your advice and first
solder it up on some of that peforated prototyping board which I have
here. Then if that works I'll have a go at my own PCB. I even know
where I can get hold of a set of PCB drills too since they've shut
down the workshop at work.

Thanks again for the helpful advice, I really appreciate it!

Cheers,
Ash.