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 12/120V inverter again
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Dec 17 2006 :  8:36:32 PM  Show Profile  Reply with Quote
2 years ago I fixed that inverter so it worked very well. My fixed schematic was recently deleted and the circuit shown now will blow up.

The output transistors in a 500W inverter must pass 25A each. The 2N3055 has a max current rating of only 15A. My circuit had 4 2N3055 transistors on each side passing only 12.5A each. I added resistors to turn off the transistors quickly. I added protection diodes.

The text in the project is a bad translation. I think the collectors "are as one" because the transistors on one side can be bolted to a heatsink without insulators then they are cooler. Their case is their collector terminal.
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cyclopsitis
Nobel Prize Winner

Canada
732 Posts

Posted - Dec 18 2006 :  09:42:01 AM  Show Profile  Click to see cyclopsitis's MSN Messenger address  Reply with Quote
audioguru,

Are you able to re design that circuit again?

How does the input DC (how many ever volts) effect the output of the inveter? maybe this question was already asked I havnt had time to read all 20+ pages of this topic. its huge!

I have another question. Lets say that I wanted to use a power supply that rectified the voltage to a higer voltage then the standard 12 or 24. how would one of these circuits have to change to invert the DC to AC.? How would this change the gate circuit.? How would you bias this so that the transistor actually works?

Tim and audioguru, thanks for your help so far i have learned alot!!

ken
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tim
Mad Scientist

198 Posts

Posted - Dec 18 2006 :  09:54:03 AM  Show Profile  Reply with Quote
well i could tell you ken that todays inverters, most, are 12 volts and are stepped up to between 140- 147 volts then rectified sent to large value caps then off to mosfet transistors where it is cut in half to get ac. but these other home made inverters rely on big transformers , npn transistors, and alot of luck that they will work after building them . not really sure about your saying 12, 24 volts but use 24 volt power on 12 volt components then expect them to fry or use a voltage regulator 24 to 12 volts.
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Dec 18 2006 :  10:32:08 AM  Show Profile  Reply with Quote
quote:
Originally posted by cyclopsitis

audioguru,

Are you able to re design that circuit again?

It is on my hard drive. But I can't attach it on this site.

quote:
How does the input DC (how many ever volts) effect the output of the inveter?

The circuit is designed for a certain DC supply voltage then the transformer steps up the AC voltage to whatever you want.

quote:
Lets say that I wanted to use a power supply that rectified the voltage to a higer voltage then the standard 12 or 24. how would one of these circuits have to change to invert the DC to AC.? How would this change the gate circuit.? How would you bias this so that the transistor actually works?

I wouldn't be difficult to modify a square-wave inverter circuit to work from any DC voltage.

Edited by - audioguru on Dec 18 2006 10:35:41 AM
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cyclopsitis
Nobel Prize Winner

Canada
732 Posts

Posted - Dec 19 2006 :  12:59:43 PM  Show Profile  Click to see cyclopsitis's MSN Messenger address  Reply with Quote
Hey Tim,

Thanks for the information! I wonder why it is so hit or miss for normal people with alot of knowledge of how circuits work to get their circuits to work.

Audioguru, Would you be able to email me the circuit you have on your HD?

Thanks
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cyclopsitis
Nobel Prize Winner

Canada
732 Posts

Posted - Dec 19 2006 :  1:02:03 PM  Show Profile  Click to see cyclopsitis's MSN Messenger address  Reply with Quote
quote:
Originally posted by tim

well i could tell you ken that todays inverters, most, are 12 volts and are stepped up to between 140- 147 volts then rectified sent to large value caps then off to mosfet transistors where it is cut in half to get ac.



How do you step up a DC voltage?
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tim
Mad Scientist

198 Posts

Posted - Dec 19 2006 :  4:49:37 PM  Show Profile  Reply with Quote
oh ken im no electronics whiz really , this stuff can be very difficult i do alot of guessing and i do get lucky sometimes , but what the hell its fun. the step up in these inverters are done within with small transformers powered by a PWM circuit with mosfets.
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Dec 19 2006 :  5:04:23 PM  Show Profile  Reply with Quote
Hi Tim,
Do those inverters use high frequency PWM to make a sine-wave output?
Then the Mosfets operate like a class-D power amplifier.
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tim
Mad Scientist

198 Posts

Posted - Dec 19 2006 :  6:13:15 PM  Show Profile  Reply with Quote
well this inverter im working on is of course , like most made in japan or china and from what i can see is its got a row of 55volt 80 amp mosfets VIA PWM DRIVING THESE SMALL TRANSFORMERS UP TO 147 VOLTS ON THE SECONDARY THEN ITS SPLIT IN 2 STAGES AGAIN VIA PWM AND HAS A ROW OF 200 VOLT 18 AMP MOSFETS TO SPLIT THE DC LEAVING AC. BUT I DONT KNOW THE HZ ON THE PRIMARY OR SECONDARY , THERE ARE 2 DRIVES, HOWEVER IT LOOKS LIKE THE BOTH SIDES SHARE THE SAME RESISTOR THAT SETS THE HZ.
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AMEERQURESHI
New Member

1 Posts

Posted - Dec 27 2006 :  12:36:13 AM  Show Profile  Reply with Quote
I am looking for a circuit diagram to make 500W 24 volt battery inverter,
If some one have, pl mail me, thank you very much,

Ameer
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jeswinjames24
New Member

India
1 Posts

Posted - Jan 04 2007 :  12:47:01 PM  Show Profile  Send jeswinjames24 a Yahoo! Message  Reply with Quote
Could you please sent me the mocified circuit schematic of the 12v DC to 120 v AC inverter.
I m a student and need to submit it as a project, please reply me in 18 hrs.
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Jan 04 2007 :  1:31:06 PM  Show Profile  Reply with Quote
There is no modified schematic. It needs an entirely different design for it to work properly.
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Jan 05 2007 :  10:39:39 AM  Show Profile  Reply with Quote
Attachments can be made here???
Here is a 500W square-wave inverter that works.
Here it is for low power.

Download Attachment: 500Watts_Inverter-small.PNG
161.26 KB



Download Attachment: 100W inverter.GIF
15.87 KB

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bala
New Member

India
2 Posts

Posted - Jan 10 2007 :  06:32:40 AM  Show Profile  Send bala an AOL message  Reply with Quote
i tried this circuit.still i dont get output. what are all the things i have to check?

boobalan
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Jan 10 2007 :  09:52:46 AM  Show Profile  Reply with Quote
Boob,
Which circuit did you make?
Check that the oscillator is oscillating.
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