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Post by wazzy on Jan 30, 2008 14:37:58 GMT -8
hi i have a question about this circuit, made the board and when power is applied one of the mosfets releases the magic smoke please help? i understand that the operation of electrical devices requires the smoke to stay in the nice packages! I'm really stumped, wanted to use for lighting as we have quite a severe energy crisis in zimbabwe, plenty sun shine though! to recharge batterys with solar panels! thanks for any assistance, nice to see a well run site.
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Post by Gary Lecomte on Jan 31, 2008 7:46:34 GMT -8
Obviously you have an ERROR, shorted trace or a faulty part somewhere.
This inverter Definately does work good, if built correctly.
Some Possible causes for your problem: 1) Improper drive to one of the mosfets? 2) Improper Phasing of the transformer Primaries? 3) A diode in backwards somewhere before that mosfet?
Unfortunately its impossible for me to be more specific, without actually being able to see it or test it for myself.
But as a "Common Sense Rule", I suggest you put an appropriate FUSE in the circuit so you don't burn out the mosfets when there is a problem.
Also, I am going on a Holiday to "Chile, South America", on Sunday. I will return home on March 3.
Good Luck.....Gary
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rmeyn
Full Member
My primary interests are electronics, sailing, bowling, and camping
Posts: 163
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Post by rmeyn on Feb 1, 2008 6:20:42 GMT -8
I've built this circuit and it works. Some suggestions... Have a friend check the wiring carefully. It could have errors. Also, be sure the wire guage connecting the mosfets is sufficiently heavy to carry the current. My first attempt at this circuit ended in failure! I smoked the current carrying lines, not the mosfet's. Also, the mosfets need to be heat sinked! They can get quit hot. Hope I helped. Richard Meyn
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Post by wazzy on Feb 1, 2008 14:59:59 GMT -8
thanx for the help guys saw the problem this evening, guess mistakes happen when you're working on something at four in the morning! thanks again! warren
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Deleted
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Post by Deleted on Sept 26, 2008 12:35:55 GMT -8
I am building a mosfet inverter and the output voltage is not stable under load . I will make a new PCB , but i would like to know how stable is the voltage under load when the inverter is built properly?
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Deleted
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Post by Deleted on Sept 26, 2008 15:14:46 GMT -8
Oh, I get it....an old thread. I though Gary was going to Chile for 6 Mos. for a minute! I think that nap slowed me down.................!
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Post by Gary Lecomte on Sept 26, 2008 19:52:49 GMT -8
I am building a mosfet inverter and the output voltage is not stable under load . I will make a new PCB , but i would like to know how stable is the voltage under load when the inverter is built properly? It Is Definately Quite Stable. It Probably isn't your Circuit Board. It is Most Likely Your Transformer. Number of Primary Windings, Wire Size, Core Size, Or a Combination of these. Ziron44, Yes its an OLD Post, But I WILL be going BACK TO CHILE. (Probably Xmas 2009) Gary
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Deleted
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Post by Deleted on Sept 26, 2008 22:16:32 GMT -8
My transformer is good. I used a MOT transformer , and i have changed the mosfets , 4001 , LM 385 . I can ged the volts by changing the trasformer turn ratio , but each time i put a load (40W light bulb ) the votage drops by half . Any suggestions ?
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Post by lamazoid on Sept 27, 2008 0:03:47 GMT -8
MOT is designed to operate at high magnetic flux and it has accordingly high idle current consumption, and it's not designed to work a long time without cooling... So MOT is not a good choice for inverter...
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Post by Gary Lecomte on Sept 27, 2008 6:06:40 GMT -8
My transformer is good. I used a MOT transformer , and i have changed the mosfets , 4001 , LM 385 . I can ged the volts by changing the trasformer turn ratio , but each time i put a load (40W light bulb ) the votage drops by half . Any suggestions ? DEFINATELY your Transformer is the Problem! Sorry, I am Not familiar with the Term "MOT" Transformer. And I hate Abbreviations. However, The Transformer Should be an Iron Core type, usually using Silicon Steel Laminates. Typically these are E/I shaped Laminates. Also the Primary should be Bifular Wound on first, with the Secondary wound Over top of the primary to give best efficiency. Typically, The Output will remain Stable, within about 5% volts of rated output. Gary
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Deleted
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Post by Deleted on Sept 28, 2008 2:05:33 GMT -8
I found two mistakes in my project . First , my power supply was to weak to power the inverter with the MOT (Microwave oven transformer) . When i hoocked it up to a car battery i got 210 V (with the car on 14.4 V and 5.5 A). I changed the MOT trasformer for the 220/12 V (150W) one that was used to power 12 V light bulbs and it works great now. Later i will try to find 500W one , and put two variable resistors on the gate of the mosfets to be able to control positive and negative amplitudes.
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Post by Gary Lecomte on Sept 28, 2008 7:06:02 GMT -8
Microwave Transformer cores are OK, BUT you need to Remove the CURRENT SHUNT Before winding it for an Inverter.
The Current Shunt are the "small Plates" Inserted beside the "E" of the laminates.
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