I have been looking into that direction as well. The problem with most cores is that they are large and for some obscure reason try to be instruction cycle accurate. For what reason? It just takes extra space and costs performance.
I have been tinkering with the idea to create an MSP430 compatible CPU core. That is a 16 bit core (small) with a very nice instruction set and there is a decent GCC compiler available for it.
on it,
may drop in price
There are many companies that sell such modules for very low prices.
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
nico@nctdevpuntnl (punt=.)
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T
Tim Williams
I had made a ~3W flyback converter at 500kHz with a #52 core, and it got noticably hot (20-30C temp rise?). I don't recall what Bmax it used...
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This is the circuit. Silly me, green-blue is #52, not MPP.
15V applied to 15T over 1us is 1uWb/t. Hmmm... T50-52D seems to be the core, though A_L is different from my measurement. Ae = 22.3mm^2, so Bmax =
45mT. (Which is 476 At/m at mu_r = 75, and l_e = 31.9 mm, so MMF = 15At. Ipk was around 1A, so that's close enough.)
On the other hand, I also made a 1MHz forward converter using a fairly small ferrite E core:
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I was thinking 0.1T peak, but for size reasons, I had to go with more like
0.3T peak, which is typical of lower frequencies. You'd think hysteresis or lossy permeability would cause problems up there. Material is probably ordinary mu = 2000 stuff, not #43. Even so, it didn't heat up noticably.
As far as I can tell, ferrite is practically lossless. Do whatever you want to it, as long as it's under 0.4T. Maybe doesn't apply so well at 10MHz+, but that's getting into RF anyway.
Hmm, continuing the earlier example, #52 is rated as 1.5W/cm^3 at 500kHz,
250 gauss peak (= 500G p-p). The core is 0.711 cm^3, so it should burn around 1.07W, which sounds about right.
As for MPP, aha! They do indeed have an MPP material, -M125, in the 200C Series.
Magnetics Inc. shows 60 mu MPP having about 70mW/cm^3 at 300kHz for the same flux density. At 500kHz, the formula evaluates to 0.18W/cm^3, so it's about
8 times lower loss.
That's not too bad. I should go buy some.
Tim
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
D
Didi
0C
ame
about
Oh, that's more than I would have hoped for. More than twice more, I guess :-).
I'll have to give them a try as well. Thanks for the insight!
Dimiter
J
Jan Panteltje
On a sunny day (Tue, 11 May 2010 11:09:15 -0400) it happened Spehro Pefhany wrote in :
150 MHz, radio hams would like that for 144 MHz. Maybe one of thsoe days....
J
JosephKK
which
OK,
it
I would have "paralleled" the two with individual 10R to the gate.
D
Didi
e:
h
,
t
Well so would have I, but the unused one will not be that forever. It will drive another gate when things get that far :-) . The FET is not soldered on that board, but the control circuitry is (duals etc. which are needed also elsewhere).
Dimiter
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