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 12/120V inverter again
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Oct 31 2009 :  8:36:31 PM  Show Profile  Reply with Quote
The inverter here does not work.
You can make a simple square-wave inverter that does work (but poorly) for the same low cost.
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00milind
New Member

India
1 Posts

Posted - Nov 01 2009 :  01:31:41 AM  Show Profile  Reply with Quote
Looking for a pure sine wave inverter design, 48V to 240V, 50Hz, if anyone can help I would appreciate it.

TEXA
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Darkthero
Apprentice

USA
51 Posts

Posted - Nov 04 2009 :  03:48:38 AM  Show Profile  Reply with Quote
i didnt take time to read all the above posts but i have posted a pic of the circuit . i have made changes, and it dose work this way. i got it sitting next to me running as i type this. notice the caps. and yes Tantalum caps do have a polarity. http://img522.imageshack.us/img522/952/inverter.gif
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Darkthero
Apprentice

USA
51 Posts

Posted - Nov 04 2009 :  03:50:30 AM  Show Profile  Reply with Quote
dont ask why im not entirely sure why. but i accidentally placed them like this and it functions
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Darkthero
Apprentice

USA
51 Posts

Posted - Nov 04 2009 :  05:37:48 AM  Show Profile  Reply with Quote
http://img522.imageshack.us/img522/952/inverter.gif
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Nov 04 2009 :  3:33:23 PM  Show Profile  Reply with Quote
quote:
Originally posted by Darkthero

dont ask why im not entirely sure why. but i accidentally placed them like this and it functions


You corrected the error of the backwards polarity of the capacitors.

But you did not correct the error where the transistors have avalanche breakdown when the capacitors try to drive the bases to -23V (the max allowed voltage is only 7V). The avalanche breakdown causes extremely high currents in the capacitors that causes them to explode even when their polarity is corrected.

You also did not correct the error where the base current for the transistors is much too small.
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Darkthero
Apprentice

USA
51 Posts

Posted - Nov 04 2009 :  4:04:52 PM  Show Profile  Reply with Quote
quote:
Originally posted by Darkthero

i didn't notice those. but the way i have it now its putting out 130v and low amps and my caps havent exploded yet

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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Nov 04 2009 :  9:25:30 PM  Show Profile  Reply with Quote
An inverter that puts out low amps is useless.
I think it wastes most of its battery power.
It is easy to modofy the circuit so that the transistors do not have avalanche breakdown. But then the base current for the transistors will still be too low.
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Cokaric
New Member

4 Posts

Posted - Dec 25 2009 :  06:39:21 AM  Show Profile  Reply with Quote
I am building ur Inverter base on this...

http://electronics-diy.com/electronic_schematic.php?id=605

I have Googled for last hour or two and finally found ur original schematic... My English lng is poor so I mostly cant understand English electronic terminology.

What I want >>
I want to build ur Inverter, I need to power my computer with it when there is no power, my professor says, with 100 Amph Accumulator it will power my computer for about 8 h, in theory 40 h, but then after I can trow battery.
What battery should I use, what transformer should I use. My grid is ~230V/50Hz. How to modify this schematic to build a 1 kW Inverter. I have 500 W power supply in my computer, what would happen if I connect my computer on 1kW Inverter...

Please can u give me ur email or some way I can contact u... What lng except English do u speak ?

Best regards,
Cokaric

The more I C, the less I see
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Dec 25 2009 :  10:36:21 AM  Show Profile  Reply with Quote
My inverter circuit was originally designed in the Orient for 3rd world countries. It didn't work so I fixed it. It is very simple so it produces a square-wave output that many electronic products do not use, and it does not have voltage regulation so its output voltage is too high with a light load or fresh battery charge and its output voltage is too low with a full load and when the battery has run down.

My 500W computer does not draw 500W all the time, only when it is crunching many numbers. Usually its power is about only 50W.

I speak only English.
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weqwedas
Apprentece

8 Posts

Posted - Dec 26 2009 :  01:27:32 AM  Show Profile  Reply with Quote
Well seeing as how you're still answering questions, I might as well ask a few of mine. I have been attempting to build an inverter to understand the concept for quite awhile now. I attempted to use both a dual-transistor flip-flop as well as the CD4047 circuit (looks almost exactly like the new light duty inverter circuit you have listed here, but with no amplifiers and a 5.1 volt Zener diode across the CD4047). Both times, however resulted in the flip-flop freezing up and dumping as much current as the 9 volt battery could through one transformer as well as the transistor that was in series with it. It was only after using two 9 volt batteries (one to power the CD4047, one to power the transformers) that I was finally able to get it to work. I noticed that because all of the current was going through the transformer, the CD4047 wasn't able to function correctly (at least that is what I can observe). Finally to the questions:

1. Could this possibly be due to the fact that I am using a 9 volt battery which cannot provide nearly enough current as a car battery?
2. Would adding the two amplifiers make the circuit more efficient or solve the previous problem? What are they there for exactly in your circuit?
3. Is it possible to run it off of a single voltage source without having the CD4047 deprived of amperage?

That should be all for now. If you need clarification on anything, I'll read it later on today.
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Dec 26 2009 :  11:18:38 AM  Show Profile  Reply with Quote
quote:
Originally posted by weqwedas

I attempted to use both a dual-transistor flip-flop as well as the CD4047 circuit (looks almost exactly like the new light duty inverter circuit you have listed here, but with no amplifiers and a 5.1 volt Zener diode across the CD4047).
Both times, however resulted in the flip-flop freezing up and dumping as much current as the 9 volt battery could through one transformer as well as the transistor that was in series with it.

Post your schematic here so I don't need to guess about it.
An inverter output is hundreds of Watts. A little 9V battery can supply only 2.2W for about 10 minutes.

Download Attachment: 9V alkaline, 250mA load.PNG
8.28 KB

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weqwedas
Apprentece

8 Posts

Posted - Dec 26 2009 :  3:23:20 PM  Show Profile  Reply with Quote


This one was the original which constantly locked up.



This one is the one that works. The concept was not really meant to power anything, just charge a capacitor. The 45 ohm resistors could probably be moved to the transformer battery side without any complications. It was modeled after the disposable camera circuits in an attempt to charge the capacitor faster.

(Edit) Hmm I just noticed that the zener there is not actually doing anything in that circuit. There used to be a 100 ohm resistor in between B2 and D1. I'll have to add that back in.

Edited by - weqwedas on Dec 26 2009 5:07:40 PM
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Dec 26 2009 :  8:08:28 PM  Show Profile  Reply with Quote
It is not a mains inverter. It makes a high voltage for a zapper or something. the transistors are not flip-flops. The first little ones are emitter-followers driving the larger ones that are common-emitter switches.

The circuit with only one battery has the battery being killed by the high current in the TIP31 transistors that stops the CD4047 oscillator.

The circuit does not need the zener diode since the max allowed supply for the CD4047 is 18V. The CD4047 has a typical output current of only 4ma when its supply is 5.1V. Its output current is 22mA when its supply is 12V.

Since a little 9V battery is very weak then the supply should have a parallel supply bypass capacitor of about 100uF.
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Cokaric
New Member

4 Posts

Posted - Dec 26 2009 :  8:21:51 PM  Show Profile  Reply with Quote
@audioguru

I was reading from page 1 so I dint saw schematic on page 54, http://www.aaroncake.net/forum/uploaded/Audioguru/20097292438_500W%20inverter%20final.PNG
Can u tell me what is F and what is SW1, I really don't know, I suppose that SW1 is switch and F relay but I am not sure. SW1 is switch does it need to be 60 A. Or maybe is SW1 relay and F fuse? What should be cross section of conductors. What should be cross section on PCB? What battery would u advise me to use?

Did u applied any other changes in ur inverter, did u improved anything and can u post here, please, if u did?

What do u think about this inverter, is MOS-Fet better or urs?
http://electronics-diy.com/electronic_schematic.php?id=609

My professor is sure that urs will work but for this one he said that no1 in our school build it before so he doesn't know if it would work.

I will continue posting in this thread thoug next few weeks, hope I wont disturb u much... Thank u for ur support =)

Best Regards,
Cokaric

The more I C, the less I see

Edited by - Cokaric on Dec 26 2009 8:24:56 PM
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