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 12/120V inverter again
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tim
Mad Scientist

198 Posts

Posted - Aug 04 2007 :  4:25:09 PM  Show Profile  Reply with Quote
well if they got a computer to ask what they ask then they can get parts mailed to them i would imagine, lol lol......
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Aug 04 2007 :  4:41:21 PM  Show Profile  Reply with Quote
They don't have any money or credit cards and they probably don't have a postal system.
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cisco229
New Member

USA
4 Posts

Posted - Aug 04 2007 :  6:38:02 PM  Show Profile  Visit cisco229's Homepage  Send cisco229 an AOL message  Reply with Quote
Hello, How are you, i wanted to build a inverter, but I am just a newbie, im tired of trying that aaroncake one, dont work, i want something simple & easy to build, even if its only 60 watts if you can help contact me At Cisco229@comcast.net, i just need to see how they work, in the most basic form then I can Do the math and make it better, thank you very much
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Aug 05 2007 :  1:10:49 PM  Show Profile  Reply with Quote
Make an oscillator from a CD4047 IC, a resistor and capacitor. The IC has two outputs which are out-of-phase and they are perfect to drive two power Mosfets that drive a center-tapped stepup transformer.
Then you will have a very simple square-wave inverter.
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mrgone
Nobel Prize Winner

USA
1176 Posts

Posted - Aug 11 2007 :  8:01:36 PM  Show Profile  Reply with Quote
How is the power (wattage) calculated? I was surprized that you need a 16 Amp Xformer to achieve only 300 watts. I know there is an efficiency consideration but the way I see it is 15 Amps X (120 volts X rms or .707) = 1272 watts. If we divide 300 by 1272 we get only 23 % efficiency of the xformer. Does this sound correct?
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Aug 11 2007 :  11:15:30 PM  Show Profile  Reply with Quote
The square-wave inverter circuit heats with about 20% of its max power output. So a 300W inverter uses 360W from the battery. The battery current flows through the low voltage winding of the transformer and through the output transistors and is 360W/12V= 30A.
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mrgone
Nobel Prize Winner

USA
1176 Posts

Posted - Aug 12 2007 :  1:31:48 PM  Show Profile  Reply with Quote
quote:
Originally posted by audioguru

The square-wave inverter circuit heats with about 20% of its max power output. So a 300W inverter uses 360W from the battery. The battery current flows through the low voltage winding of the transformer and through the output transistors and is 360W/12V= 30A.



OK, Would it be more efficient if you shape the wave first? You could get some reasonable facsimile of a sine wave using an RC filter arangement. Also what you were talking about above. I do the same thing with 74HC04s (inverters). Make an oscillator with it and feed the output to the remaining inverters to get the two phases.
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Aug 12 2007 :  2:05:23 PM  Show Profile  Reply with Quote
If you feed a sine-wave shaped waveform into power transistors or power Mosfets then they spend plenty of time with a high current and a voltage across them. Then their power dissipation (heating) is the current times the voltage. It will be a tremendous amount of heat to get rid of and it makes a tremendous waste of battery power.

An efficient sine-wave inverter switches the transistors on and off at a high frequency. Then pulse-width-modulation changes the width of the pulses so the average current in the transformer is a sine-wave.
The transistors remain fairly cool because when they have a high current then their voltage is nearly zero and when they have voltage then their current is zero.
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newjazzy2005
Apprentece

5 Posts

Posted - Aug 20 2007 :  12:19:59 PM  Show Profile  Reply with Quote
can any one help me with i.c inverter cuicuit schmatic diagram
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Aug 20 2007 :  12:48:22 PM  Show Profile  Reply with Quote
What help do you need? Attach your schematic.
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mrgone
Nobel Prize Winner

USA
1176 Posts

Posted - Aug 20 2007 :  5:01:13 PM  Show Profile  Reply with Quote
quote:
Originally posted by newjazzy2005

can any one help me with i.c inverter cuicuit schmatic diagram



Do you mean this one? I posted this in another thread.

Download Attachment: Inverter1.JPG
25.26 KB
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kivdenn
Nobel Prize Winner

Uganda
535 Posts

Posted - Sep 27 2007 :  08:16:03 AM  Show Profile  Reply with Quote
What wave form does this one produce?, Does it have a low voltage shutdown? Which pin goes to Vcc and the ground and to which pins are the mosfet chanels connected? SOme capacitor valus are not shown like c3 to c6 Thanks
Dennis

Edited by - kivdenn on Sep 27 2007 08:18:12 AM
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Sep 27 2007 :  10:35:00 AM  Show Profile  Reply with Quote
Its outputs are filtered into almost a sinewave.
It uses an old fashioned TTL logic inverter IC that needs a regulated 5V supply.

It doesn't have low voltage shutdown. Its output voltage isn't high enough to drive Mosfets.

If you try to make a sine-wave inverter using a sine-wave input into a Mosfet amplifier then they will get extremely hot and waste a lot of battery power.
A sine-wave inverter switches its Mosfets completely on and off so they don't get too hot and so they don't waste a lot of battery power. They are switched at a high frequency and pulse-width-modulation is used to make a stepped sine-wave that is filtered into a good sine-wave.
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Ruben
New Member

USA
1 Posts

Posted - Oct 01 2007 :  8:07:42 PM  Show Profile  Reply with Quote
quote:
Originally posted by ZETABOY

Any have a plan plans for build an Iverter of 5000 watts. i want build a inverter of 5000watts or more bigger

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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Oct 01 2007 :  9:24:39 PM  Show Profile  Reply with Quote
Where are you going to get 6000W of power to power the 5000W inverter? 8 huge car batteries would last only 1 hour. 32 huge car batteries would last only 5 hours.
The transformer would cost a fortune.
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