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Re: Potential issues with oaa_ lib


On Tue, 31 Aug 2010, Lorenzo Marcantonio wrote:

On Tue, 31 Aug 2010, Vesa Solonen wrote:

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).

It's 200A 8V design :D so 1.5V SCR on state drop _is_ significant. Something to consider for low voltage high current switching: http://www.irf.com/product-info/datasheets/data/irf1324s-7ppbf.pdf

Those are way better even one has to use two back to back and some in parallel for 200A. I'd bet the combination is also cheaper than a 250A SCR.

the trick usually is the vacuum adesion of the photofilm to the focal

Yes, someone doing demanding work would easily afford a small vacuum system, be it an aspirator or compressor from an old fridge.

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).

I had to practise somewhat too. Few important points are proper paper (matt coated thin ~80g/m2) and a laminator with good temperature control. (PD-contoroller for fast response) Proper cleaning of the substrate is also a must and many amino alcohol based detergents work great on copper as they bond organic hooks to the copper chemically, making good friends with polymer based ink.

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.

If fumes don't matter then HCl peroxide is even more flash :D No storge possibilities though... It seems ferric is the easiest, if you don't count the stains :)