12v=19v 4,7A dcdc

[cjk2]

The MTP75N06E do seem to be hard to find. Try something like a IPP120N06N. They are about $1.7 from digikey, and should be a little easier to switch.

Really, you can look for any MOSFET with low on resistance, and low gate capacitance.

[mw3kgq]

Thanks
i will try them then, just looking around the web alot of other people are having the same issue. people have recomended all different types of mosfets so it doesnt appear to be too critical.
thanks for the info

[mw3kgq]

ok,
just found something else out for people following this build in the future the NTP75N06 is a direct replacment for the orignal mosfet and is easily obtainable from farnell,

[N-Channel]

Originally posted by N-Channel

....As for my humble little setup, depending on the load being drawn, if it draws, say 500W continuously (w/o the engine), maybe it would last say, six hours....

I must've been on drugs or something. At 500W, it will last 4.08 hours, under IDEAL conditions, with the extra batteries (1.92 with only the two on-board 40Ah batteries) which we rarely, if ever, encounter, not the 6 hours originally predicted. I would say more like 3.5 hours, tops, with the extra batteries, and 1.5hours w/o them, then much longer with the engine running.

[mw3kgq]

i have built this DC/DC convertor and it does work very well
it powers my 6 amp laptop with ease and has no problems at all with overheating e.t.c even inside a inclosed metal box. i used a smaller core for the coil feeding the MOSFET's, then the one sugested and i found that it works just as well, but the same colour code white/yellow
this design is well worth saving. and still very price competitive against the comercial units, worked first time as well only thing i needed to adjust was the feedback resistors the ones originally
gave me 21v maybe because of slightly different variations of components. but now it stays at a nice 19.3 v.
thanks for sharing your desgin.

[lumanauw]

Hi, N-channel,

I saw the common choke boost regulator, very interesting
In L1 (2x33uH), the twin phase boost regulator, are they cancelling each other flux (making Bmax twice the ordinary boost regulator)? The energy transfer happens in the other side when one side's mosfet is ON?

[N-Channel]

See Post #74, this thread. As the opposite F takes over, any remaining flux is automatically cancelled out. Energy is stored during the MOSFET's ON time, and released during it's OFF time. Once the period is complete, when the opposite MOSFET turns on, that is when any remaining flux in the core is cancelled out.

[lumanauw]

We know that ordinary boost regulator is not efficient in ferrite size, since it only use 1 quadrant for its operation.

With your topology (twin boost on common choke), I think that this problem is solved, the core is now more efficient (there's resetting mechanism like in push-pull).

The core size VS power handling is now improved, compared to ordinary boost regulator. Am I right here?

[N-Channel]

You are indeed correct. Thanks for the compliment on it being my topology, however I'm sure proper credit is deserved elsewhere.

Anyway, with two of the four quadrants now being used, power density is effectively doubled, and efficiency goes up.

I originally got this idea from the many application notes that come in the monthly issue of Electronic Design. They go up to five Fs, but the majority I have seen are two or three Fs. I think two is sufficient, especially since that's the number that will work on a common core.

[N-Channel]

All:

Here are a few pics of my new 12V to 19V DC-DC Uppie I am doing for a laptop. I gutted several old Dell PA-1 & PA-2 AC-DC Laptop powerr supplies and re-did them with the aforementioned 2-F topology. Since making my own pc Boards is a royal pain in the a$$, I decided to do them in Express PCB, and have Them professionally done. Double-sided, plated through, but no silk-screening, and no solder mask (who needs 'em anyway?). 6 boards for a little over US $110.00. Can't wait to finish them in time for Field Day.

Comments, Please.