kicad-developers team mailing list archive

[Lorenzo Marcantonio <l.marcantonio@xxxxxxxxxxxx>]

On Tue, 31 Aug 2010, Vesa Solonen wrote:

> On Mon, 30 Aug 2010, Alex G wrote:
>
> > :-p ). The most I'm planning to tackle is 200A at 7V switched from the
> > AC line.
>
> Sounds interesting, especially the possible uses (please tell off the list ;)

Uhm... a TIG solder machine, maybe?:D:D

> If 100Hz switcher counts, I've made such from (really)old telecom psu 
> components about ten years ago. 70kgs with wheels, but _very_ difficult to 
> break. Just some weeks ago I thought updating the controller design to the 
> digital age and also replacing SCRs with synthetic mosfet ones to cut 300W 
> from the losses. Fortunately I got my sanity back a few minutes later :)

Strange, at that those current usually losses from SCR are minimal
compared to the RDSon (unless you use IGBTs, of course).

> They probably used better collimated light source than a led matrix though.

Big exposing unit are simply huge lamps with a condenser in front... the
trick usually is the vacuum adesion of the photofilm to the focal
plane.

> I'm mostly doing toner transfers for prototypes with 12mil minimum width.

Never got a decent direct transfer. 12mil is usually feasible at home
with a little practice (never tried it, anyway).

> The etch chemistry means a lot in home brew with inefficient agitation etc, 
> and the finest + cheapest is stabilized sulphuric acid-hydrogen peroxide aka 
> "peroxy-sulfuric" etch. Works very well unstirred, excellent etch quality

We call it flash-etch since it's faster :D We bought a cheap bubbling
tank with heater (70EUR, was an offer on RS) and it works fine with
traditional ferric stuff. But, that said, I dont do more than 4-5 etches
a year.

--
Lorenzo Marcantonio
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