12v=19v 4,7A dcdc - Page 2

jamesrnz · 5th January 2007, 05:51 PM

mmmmm.

that about what my generator looks like. i did mine before the internet.

N-Channel · 8th January 2007, 03:52 AM

Guys,

this is what I have been working on for the last two years! Paralysis by over-analysis. I have two engines: 3.5HP B&S vertical shaft w/electric start (I have to be the first kid on my block to say I have a DIY electric-start Generator!), and a 6.0HP B&S OHV vertical shaft w/pull- & electric start. Both from eBay, both new & unused.

Gen 1 (6HP): will be driving a Delco CS-144 140A alternator (also from eBay) into a 90Ah deep-cycle battery with a Xantrex Pro-Sine 1800 Inverter (Again, from eBay). Good for Field Day or whenever I need QUIET power anywhere, like showing movies in the park after dark, or for camping. Oh yeah, I will be able to jump-start dead cars, too.

Gen 2 (3.5HP): This will drive another CS-144 140A (New, $35.00 on eBay) into a pair of 40Ah Union deep-cycle batteries. This one will be mainly for 12V applications, like Field Day, jump-starting, or where no 120VAC will be needed.

Both engines have 6V motors for the starters, with small alternator coils near the flywheels to recharge the batteries. All engines, alternators and batteries were new at time of purchase. Forgot, one of the guys in our ham radio club works for Detroit Edison, and has access to all kinds of batteries, 6V & 12V. If shipping wasn't so darned expensive, not to mention the HAZMAT issues with shipping batteries, I would send some your way.

James- I contemplated doing a 10SI for the 3.5HP, but I actually stumbled across the second CS for cheaper than the SI.

I have done alot of websearches for "DIY homemade Generator", "Homebrew Generator", etc., and have downloaded many pics of them. The most info comes from theepicenter.com, but also check out NS8O's webpage. It appears he is a welder, and he makes his own custom made frames for generators. Do a Yahoo! or Google search for NS8O.

Luka,

I did do a buck converter, but not with the SG3525. Mostly with Nat Semi SimpleSwitcher ICs.

I know I promised pics and a schematic of my 2-F boost converter, but it has been crazy around here. I will post them ASAP, as well as the "progress" I am making on both gen sets.

Cheers Everyone,
Steve

luka · 8th January 2007, 05:42 AM

Hi Steve

If you have a schema of buck converter that would be great, coz I don't have any idea how to drive mosfet except if I use IR.But they aren't that cheap, well at least most of the time

N-Channel · 8th January 2007, 03:03 PM

Luka,

Check out these datasheets from National Semiconductor:

http://cache.national.com/ds/LM/LM2576.pdf (3A Buck, 52kHz)
http://cache.national.com/ds/LM/LM2596.pdf (3A Buck, 150kHz)
http://cache.national.com/ds/LM/LM2677.pdf (5A Buck, 260-400kHz)
http://cache.national.com/ds/LM/LM2678.pdf (5A Buck, 260kHz)

Also, I stand corrected: I did do a Buck a long time ago using the LM1524 driving a BIG P-Channel MOSFET, but I do not have it in any schematic CAD package. I have never done a Buck using an N-Channel, but if I were to do one, I would have a Charge-pump to supply the higher-than-the-rail voltage needed to properly drive it..

Here is an interesting Application Note from the old Unitrode on using an N-Channel as a High-side switch in a buck. It uses a UCC3803, but I suspect it would work just as well with any of the UC384X chips.

Steve

luka · 8th January 2007, 03:27 PM

yes makin one from 5 or 12 isn't hard, but from 40v is since uc can't handle that much

N-Channel · 8th January 2007, 06:57 PM

How much current ya' drawin'? If less than a couple a' amps, then try these:

1) LM2592HVS-ADJ (150kHz, 2A, 65V in max, adjustable output, surface-mount)
2) LM2592HVT-ADJ (same as #1, but 5-Pin through-hole TO-220)
3) LM2576HVS-ADJ (52kHz, 3A, 65V in max, adjustable output, surface mount)
4) LM2576HVT-ADJ (same as #3, but 5-Pin through-hole TO-220)

-----OR-----

You could use an SG3525 like Fig. 10 of the Datasheet for the SG3525A from ONSemi. I would use a zener regulator to drop the 40V down to, say, 15V for powering the '3525's +VCC & +Vc pins. Then use either a BIG PNP or P-Channel as the switch.

Good suggestion for P-CH: RFG60P05E from Harris. 50V DSS (OK for 40V), 60A I(d), and Rds(on) of only 0.026 ohms! Have them sample you some, or better yet, send me email and I can send you some, as I have a boatload of 'em here just gathering dust.

N-Channel · 10th January 2007, 05:00 AM

As promised, here are the pics of my 2-F interleaved DC-DC boost converter.

N-Channel · 10th January 2007, 05:01 AM

Here it is........

N-Channel · 10th January 2007, 05:09 AM

And this one...............

N-Channel · 10th January 2007, 05:12 AM

And Finally................

8th January 2007, 05:42 AM	#13
luka diyAudio Member Join Date: Sep 2005 Location: in Slovenia :)	Hi Steve If you have a schema of buck converter that would be great, coz I don't have any idea how to drive mosfet except if I use IR.But they aren't that cheap, well at least most of the time __________________ home page @ http://www.classdaudio.tk/ @ 24/7 all year long I FEEL SLOVENIA

8th January 2007, 03:27 PM	#15
luka diyAudio Member Join Date: Sep 2005 Location: in Slovenia :)	yes makin one from 5 or 12 isn't hard, but from 40v is since uc can't handle that much __________________ home page @ http://www.classdaudio.tk/ @ 24/7 all year long I FEEL SLOVENIA

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5th January 2007, 05:51 PM	#11
jamesrnz diyAudio Member Join Date: Aug 2005	mmmmm. that about what my generator looks like. i did mine before the internet.

8th January 2007, 03:52 AM	#12
N-Channel diyAudio Member Join Date: Mar 2003 Location: Sol System	Guys, this is what I have been working on for the last two years! Paralysis by over-analysis. I have two engines: 3.5HP B&S vertical shaft w/electric start (I have to be the first kid on my block to say I have a DIY electric-start Generator!), and a 6.0HP B&S OHV vertical shaft w/pull- & electric start. Both from eBay, both new & unused. Gen 1 (6HP): will be driving a Delco CS-144 140A alternator (also from eBay) into a 90Ah deep-cycle battery with a Xantrex Pro-Sine 1800 Inverter (Again, from eBay). Good for Field Day or whenever I need QUIET power anywhere, like showing movies in the park after dark, or for camping. Oh yeah, I will be able to jump-start dead cars, too. Gen 2 (3.5HP): This will drive another CS-144 140A (New, $35.00 on eBay) into a pair of 40Ah Union deep-cycle batteries. This one will be mainly for 12V applications, like Field Day, jump-starting, or where no 120VAC will be needed. Both engines have 6V motors for the starters, with small alternator coils near the flywheels to recharge the batteries. All engines, alternators and batteries were new at time of purchase. Forgot, one of the guys in our ham radio club works for Detroit Edison, and has access to all kinds of batteries, 6V & 12V. If shipping wasn't so darned expensive, not to mention the HAZMAT issues with shipping batteries, I would send some your way. James- I contemplated doing a 10SI for the 3.5HP, but I actually stumbled across the second CS for cheaper than the SI. I have done alot of websearches for "DIY homemade Generator", "Homebrew Generator", etc., and have downloaded many pics of them. The most info comes from theepicenter.com, but also check out NS8O's webpage. It appears he is a welder, and he makes his own custom made frames for generators. Do a Yahoo! or Google search for NS8O. Luka, I did do a buck converter, but not with the SG3525. Mostly with Nat Semi SimpleSwitcher ICs. I know I promised pics and a schematic of my 2-F boost converter, but it has been crazy around here. I will post them ASAP, as well as the "progress" I am making on both gen sets. Cheers Everyone, Steve

8th January 2007, 06:57 PM	#16
N-Channel diyAudio Member Join Date: Mar 2003 Location: Sol System	How much current ya' drawin'? If less than a couple a' amps, then try these: 1) LM2592HVS-ADJ (150kHz, 2A, 65V in max, adjustable output, surface-mount) 2) LM2592HVT-ADJ (same as #1, but 5-Pin through-hole TO-220) 3) LM2576HVS-ADJ (52kHz, 3A, 65V in max, adjustable output, surface mount) 4) LM2576HVT-ADJ (same as #3, but 5-Pin through-hole TO-220) -----OR----- You could use an SG3525 like Fig. 10 of the Datasheet for the SG3525A from ONSemi. I would use a zener regulator to drop the 40V down to, say, 15V for powering the '3525's +VCC & +Vc pins. Then use either a BIG PNP or P-Channel as the switch. Good suggestion for P-CH: RFG60P05E from Harris. 50V DSS (OK for 40V), 60A I(d), and Rds(on) of only 0.026 ohms! Have them sample you some, or better yet, send me email and I can send you some, as I have a boatload of 'em here just gathering dust.