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 12/120V inverter again
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Jun 02 2004 :  10:20:11 PM  Show Profile  Reply with Quote
SupraGuy,
You just copied Wasssup's complicated circuit and are even using his obsolete MOSFETs.
Since you found a TI CD4047, don't you like my simple idea?
I agree that high-power transformers are hard to find. Buy them from an inverter manufacturer.

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n/a
DELETED (Inactive)

56 Posts

Posted - Jun 03 2004 :  02:54:03 AM  Show Profile  Reply with Quote
Well, yes. And I started the complicated one before I got to the "simple"

I can't find direct info on the R/C relationship to set frequency, so it's hard to choose component values, but having the pins labelled "R", "C", and "RCCOMMON" is a big hint as to where to put stuff. :) I'd guess that Q and Q' are the opposing outputs, but I'm missing information as to what voltage/current I can expect at the outputs. I'm working on a schematic working on the assumption that I can have a couple of mA at close to the supply voltage. I'm not all that great on reading the data sheets, so It's more than possible that I'm wrong. :P

If I can have reasonable voltage, I'd rather use (inexpensive) transistors, rather than big MOSFETs. Also, since I'm looking for considerably less than 300W (At least at first) something really common like 2N3055 transistors (Which I have a bunch of already, making them even cheaper.) Well, let's start from a minimalistic KISS principle, and add headaches from there.

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n/a
DELETED (Inactive)

56 Posts

Posted - Jun 03 2004 :  04:29:00 AM  Show Profile  Reply with Quote
Okay. New attempt at http://www.abstractconsulting.com/~dan/images/Inverter2.gif

Probably full of flaws. Let me know what they are! :P


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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Jun 03 2004 :  07:32:42 AM  Show Profile  Reply with Quote
SupraGuy,
Problems? Yea:
1) The R pin of a 4047 is rated for a minimum of 10K, so your R1 is 100 times too small. Use 39K or 47K.Therefore its capacitor, C3, is way too big. Use 0.1 microfarads.
2) The 4047 does not like to drive the dead-short-load of a transistor's base-emitter junction, so add resistors in series with its outputs to the transistors' bases.
3) The 4047 can provide about 12mA from its outputs on a 12V supply, so a 2N3055 that it is driving through a resistor will conduct a minimum of only 360mA. The power ouput of your inverter is only 3.5W
4) Your D2 and D3 protection diodes are a dead short across the transformer. Since the transformer's center-tap is at +12V, then transformer action defines that if 1 side is driven to ground, then the other side will swing to +24V. That's why we are using a 24V transformer with a 12V battery
5) Where are you going to find a transformer with such a small voltage ratio?.

Use Google to see the data sheets for CD4047 and 2N3055.

You have lotsa 2N3055s? Here is a 700W (coservatively rated at only 500W by artist) that I helped design:
http://www.electronics-lab.com/forum/attachments/500Watts_Inverter.gif


.



http://www.electronics-lab.com/forum/attachments/500Watts_Inverter.gif

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shivick21
Apprentice

Philippines
57 Posts

Posted - Jun 03 2004 :  07:59:07 AM  Show Profile  Send shivick21 a Yahoo! Message  Reply with Quote
neat!!have you build this one? does it work? the parts are much easier to find but,,,, i have the 2N3055 Surface mounted transistor, now how do i suppose to put this thing? in your diagram the base itself is conneted to another 2 transistor so where and how could i mount this thing? and those this thing emmits heat? like the usual transistor? and one ither thing, pcb boards? du have a ilistration? hehe thats all

Aki-kun "Pls! tank me! Im a noobs"
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Jun 03 2004 :  3:16:56 PM  Show Profile  Reply with Quote
To All,
The first 500W inverter was reported today, to deliver 780W output:
(Qupte)
Topic Summary
Posted by: Chip Posted on: Today at 12:19:24pm
Audioguru

Inverter is working fine at 780W
I will send a picture of this monster as soon as it will be in the box. I have added a charging circuit for battery which can charge at 6A from solar cells.
Well I coudn`t get the 70amp power switch so I put only a tiny switch for control part of the inverter and it works fine.
(Quote)



.

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n/a
DELETED (Inactive)

56 Posts

Posted - Jun 03 2004 :  11:31:06 PM  Show Profile  Reply with Quote
Okay... If that inverter works so well, it would make sense to just use it. :) Just gotta get a transformer to work with.

I did fix most of the problems with the circuit (I think.)

New schematic at http://www.abstractconsulting.com/~dan/images/Inverter3.gif


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shivick21
Apprentice

Philippines
57 Posts

Posted - Jun 05 2004 :  12:34:15 PM  Show Profile  Send shivick21 a Yahoo! Message  Reply with Quote
hi, does this inverter u post is working? or have u tested it to work on specific components? eg for pc?

Aki-kun "Pls! tank me! Im a noobs"
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Jun 05 2004 :  2:17:38 PM  Show Profile  Reply with Quote
SupraGuy,
Your circuit still has problems:
1) Q5 and Q6 turn-off the output stages, but there is nothing to turn them on.
2) "Your D2 and D3 protection diodes are a dead short across the transformer. Since the transformer's center-tap is at +12V, then transformer action defines that if 1 side is driven to ground, then the other side will swing to +24V. That's why we are using a 24V transformer with a 12V battery". As I explained before.

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n/a
DELETED (Inactive)

56 Posts

Posted - Jun 05 2004 :  6:20:38 PM  Show Profile  Reply with Quote
Heh.
1) Oops.

2: D'OH! I'd fixed it, then "fixed" it again. Gotta stop working on this stuff at 2 AM.

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n/a
DELETED (Inactive)

1 Posts

Posted - Jul 25 2004 :  09:58:41 AM  Show Profile  Reply with Quote
I'm a little new to this power inverter thing, but if all you want is rough sine wave, couldn't you use a 555 timer with low voltage RC circuit for rounding the wave form, then amplify it, then step it up with T1? Is that a bad approach? I can see how pushing large current through any type of cap is going to cause problems sooner or later.

Also, you guys who are looking for some large transformers might need to look at old ham radio equipment power supplies. Even burned out ones usally the transformers are good and of the voltages/current you can use believe.

Edited by - frankswd on Jul 25 2004 10:10:14 AM

Edited by - frankswd on Jul 25 2004 10:17:20 AM
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Jul 27 2004 :  7:42:41 PM  Show Profile  Reply with Quote
Frank,
Why do you need a sine-wave? Heaters, motors and lights don't care if it is an efficient square-wave.
If you amplify a sine-wave, then the amplifier will heatup a lot since its output is near "halfway" most of the time. Since a square-wave inverter switches fully-on and fully-off, it is much cooler. The wasted heat from a sine-wave inverter runs-down its battery sooner.
Besides, the amplifier will need a very high current output.

Edited by - audioguru on Jul 27 2004 7:45:51 PM
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marius
Apprentece

Israel
11 Posts

Posted - Jul 28 2004 :  09:17:26 AM  Show Profile  Reply with Quote
But what about TV's, radions and other similar appliances ? Can they work with your suggested schematics from here ?
http://www.electronics-lab.com/forum/attachments/500Watts_Inverter.gif
quote:

Frank,
Why do you need a sine-wave? Heaters, motors and lights don't care if it is an efficient square-wave.
If you amplify a sine-wave, then the amplifier will heatup a lot since its output is near "halfway" most of the time. Since a square-wave inverter switches fully-on and fully-off, it is much cooler. The wasted heat from a sine-wave inverter runs-down its battery sooner.
Besides, the amplifier will need a very high current output.

Edited by - audioguru on Jul 27 2004 7:45:51 PM



Marius
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n/a
DELETED (Inactive)

56 Posts

Posted - Jul 28 2004 :  11:51:06 AM  Show Profile  Reply with Quote
most devices will work fine with a square wave inverter. Almost any semicondictor based device (TV, Radio, computer, etc) juist uses a tranformer to conver the voltages to the desired values, ten rectifies it to DC anyway, after which it doesn't matter what the original waveform was. (It also doesn't matter what the frequency of the AC signal was, either.)

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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Jul 28 2004 :  11:54:04 AM  Show Profile  Reply with Quote
Marius,
That 500W inverter is used to power TVs and flourescent lights.

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