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 12/120V inverter again
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wasssup1990
Nobel Prize Winner

A Land Down Under
2261 Posts

Posted - Mar 01 2005 :  12:10:22 AM  Show Profile  Visit wasssup1990's Homepage  Reply with Quote
G'day buddy:
Obviously they are ripping us off. I bought a toroidal transformer for 70 bucks aussie $! God damn it, it ain't fair. Money money money thats all they want. Jaycar, one of my main suppliers of electrical parts buys nearly all of there stuff from ELECTUS which is a distributer. Now of course Jaycar want some profit, so what do they do? They increase their sale price about $25 more. And guess what, ELECTUS get there Toroidal transformers from China, surely they don't get them for much if they'r from there. Or do they? So I don no?

quote:
The microwave ovens sell for a price that is way less than the cost of a transformer that size.
Who pays for all that shipping? When I ship something, I'm charged by the weight. Aren't they?


They must get the money from somewhere. I wouldn't have a clue at the moment.

Those transformers arn't mine. I found a site when I typed "stupid experiments" into a Google search. When I was looking through the pages I found those transformers.

http://www.geocities.com/CapeCanaveral/Campus/1245/index.htm
This is the site I found them on. Click on "Adam's garage", there will be a pile of pictures to look at. Some very heavy-duty electronics there. Oooo, I wish I had all that stuff, hehe. Look at his Tesla! It puts out 1/2 a million volts! The stupid experiments he does is quite interesting and educating. The most funniest one is when he shoved a T.V. into his microwave. What a mainiac! I thought the caps would explode in the T.V.

See ya!

J.C.
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gguyen
New Member

USA
2 Posts

Posted - Mar 15 2005 :  02:39:17 AM  Show Profile  Send gguyen a Yahoo! Message  Reply with Quote
Hello, everyone, I am trying to put this circuit into (P)Spice, as part of my design project, I wonder what the characteristics coef, Bf) for the NPN, and DIODE.
Specifically I am looking for the following paramters:
Is -> sat. current for D, NPN
Bf -> forward-emitter current gain for for NPN
N -> emission coefficient for D
Without knowing this I am going for default parameters built into Spice. so not sure it will work.
Anyone could give me a clue or direction I would really appreciate it. Please e=mail me. THanks a lot!
guyen000@yahoo.com


helloo!!
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Mar 15 2005 :  04:26:01 AM  Show Profile  Reply with Quote
Hi GG,
The datasheets for the diode and transistor provide all their spec's. The datasheets can be found at www.google.com .

Simple math shows that this circuit can't provide much output power with its 180 ohms base resistors for the transistors, because power transistors don't have much current gain.

You and your spice simulator might not understand that the capacitors are shown backwards on the schematic and when they are attempting to drive the bases of the transistors to minus 23V, cause the emitter-base junction of the transistors to avalanche-breakdown at about minus 7V causing damage to the capacitors and transistors.

Therefore most of the small output power is used to destroy the capacitors and transistors.

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gguyen
New Member

USA
2 Posts

Posted - Mar 15 2005 :  05:21:57 AM  Show Profile  Send gguyen a Yahoo! Message  Reply with Quote
thanks guru, but it is way over my head, any solution to teh problem. I succesfully simulated on the output window, the Vout was sinusoidal but it breaks down after about a second with current thru R3 and R4 goes to infinity exactly at the same time. Any solution to the problem

helloo!!
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Mar 15 2005 :  06:48:13 AM  Show Profile  Reply with Quote
It's a square-wave oscillator, not sinusoidal.

It requires a high voltage across the resistors to create high currents in them. Where is the high voltage coming from?

It looks like your spice simulator doesn't know what to do with this odd circuit.

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phoenix
Apprentice

Canada
54 Posts

Posted - Mar 19 2005 :  06:39:50 AM  Show Profile  Visit phoenix's Homepage  Send phoenix a Yahoo! Message  Reply with Quote
Hi Guyz...
I've been trying out lots of inverter circuits, most of my projects have been on inverters, but it's been quite difficult getting a suitable circuit... I need a circuit that could produce enough current to power a few bulbs, + TV + a small refridgerator and still run for about 4hrs on a 24v batt (two car batteries)...
I also need to know other kinds of transformers I could use ( can't get a micowave oven transformer) ...
Cheers...

T-boss
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Mar 19 2005 :  08:07:59 AM  Show Profile  Reply with Quote
Hi Phoenix,
It sounds like you need an inverter that is rated for 500W.
If you can't get a microwave oven transformer, there is another item that has a suitable transformer: a 500W inverter!

Cheap imported inverters are available that work well and are small because they use Mosfets instead of ordinary transistors. The inverters even have a digital display that shows how much power their load is drawing, and error conditions such as over-temp, over-current or low-batt.
You could take the transformer out of one of these beautiful little inverters and use it in your big ugly inverter.

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phoenix
Apprentice

Canada
54 Posts

Posted - Mar 19 2005 :  1:36:58 PM  Show Profile  Visit phoenix's Homepage  Send phoenix a Yahoo! Message  Reply with Quote
Thanks a lot, but... if I could get a big empty transformer & wind the coils myself, what 'guage/ size' do I use on each side?
Thanx

T-boss
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Mar 19 2005 :  5:08:31 PM  Show Profile  Reply with Quote
Hi Phoenix,
The wire size is determined by its current which is determined by its power. Do you think that 500W is enough?
Which circuit are you going to use?
Will your TV run on square waves?

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tt1493
Apprentece

Hong Kong
15 Posts

Posted - Mar 20 2005 :  10:28:08 PM  Show Profile  Reply with Quote
Hi. i have a question as below related this topic.
If i would like to have 240Vac output (50Hz), but i only have 6Vdc input(Regulated). How to adjust the parameter for the each devices on the schematic diagram?
Thank you.
TT


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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Mar 21 2005 :  12:16:43 AM  Show Profile  Reply with Quote
Hi TT,
Aaron's inverter project won't have transistor breakdown problems with a 6V supply. You must reverse the polarity of the capacitors from how they are drawn on the schematic. Since the transistors won't breakdown anymore, the frequency will be different. Experiment with different value capacitors until it runs at 50Hz.

You might get 30W out of it if you use a 50W 240/6-0-6 transformer connected in reverse. With a 30W load it will draw about 6A from your 6V power supply.
You probably won't get much more than about 30W out of it without a complete re-design.


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Polo G40
Apprentece

Italy
7 Posts

Posted - Apr 05 2005 :  09:26:38 AM  Show Profile  Reply with Quote
quote:


hi all 'im italian..
i need 220vac and 300w ...
i don't know what transfo to be used...
24/24/220v or 12/12/220v??
and the watts of transfo??
thanks for reply...
thunderbolt1@aliceposta.it




(Edit...Remove email notification due to bad address...)

Edited by - Aaron Cake on Nov 25 2005 09:16:41 AM
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Apr 05 2005 :  09:40:29 AM  Show Profile  Reply with Quote
A 12-0-12/240V 360W transformer will put out a 220V/300W square wave from an efficient inverter circuit. Where are you going to find an efficient 360W inverter circuit?

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Polo G40
Apprentece

Italy
7 Posts

Posted - Apr 05 2005 :  10:23:56 AM  Show Profile  Reply with Quote
quote:

this circuit make a square wave??



(Edit...Remove email notification due to bad address...)

Edited by - Aaron Cake on Nov 25 2005 09:16:43 AM
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Polo G40
Apprentece

Italy
7 Posts

Posted - Apr 05 2005 :  10:42:02 AM  Show Profile  Reply with Quote
quote:

i need a circuits that make synusoid...
i' ve one that is a 12/220vac inverter synusoid but the power output is 1.5w...
i need a power amplifier..



(Edit...Remove email notification due to bad address...)

Edited by - Aaron Cake on Nov 25 2005 09:16:52 AM
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