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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Apr 11 2009 :  10:32:46 AM  Show Profile  Reply with Quote
This inverter circuit does not work.
Its capacitors have backwards polarity so they blow up.
The transistors have avalanche breakdown of their emitter-base junctions so they waste most of the current by blowing up the capacitors even if their polarity is corrected.
The transistors do not have enough base current for an inverter.

Look up Transistor Multivibrator Circuit in Google. The Wikipedia article mentions protection diodes to avoid emitter-base breakdown of the transistors.
Some articles have the polarity of the capacitors backwards.
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mrgraph003@yahoo.com
New Member

USA
1 Posts

Posted - Apr 22 2009 :  5:30:23 PM  Show Profile  Reply with Quote
quote:
Originally posted by audioguru

Changing T1, Q1 and Q2 in this simple circuit has nothing to do with increasing its output power because the circuit doesn't work. Its output power is only about 25W with a low output voltage, not anywhere near 300W.

The polarity of the capacitors are backwards and the transistors have avalanche breakdown. The transistors don't have enough base current.

You want the math? It is difficult to determine how much power is wasted by heating the backwards capacitors with the very high current pulses caused by the transistors avalanching.
The transistors have base resistors that are 180 ohms so the base current is only (13.2V - 1.0V)/180= 68mA. The typical current gain is 50 so the collector current is 3.4A. The output power is 13.2V x 3.4A= 44.9W minus the wasted power. The transistors saturate poorly unless the base current is much higher. If your transistors have minimum gain then the output power and voltage will be much lower.

For an output power of 300W then the power from the battery must be about 360W. Then the current in each transistor must be 360W/13.2V= 27.3A. But the absolute max allowed current for the 2N3055 transistors is 15A and they work poorly at 10A to 15A. I don't know of a power transistor that has a good current gain with a current of 27.3A.

Kasamiko's inverter is 500W and uses 8 2N3055 output transistors, 2 2N3055 driver transistors plus pre-driver transistors. It has a separate oscillator so its transistors do not have avalanche breakdown and its capacitors use low power.

5000W is rediculous from a 12V battery. The current would be 500A!

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dimestone
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Posted - Apr 24 2009 :  9:35:46 PM  Show Profile  Visit dimestone's Homepage  Send dimestone an AOL message  Send dimestone an ICQ Message  Click to see dimestone's MSN Messenger address  Send dimestone a Yahoo! Message  Reply with Quote
I got familiar with this forum yesterday, I read the 52 pages in this forum and followed many of the links to their destination. It took a while to read it all, hours. Feel like I've known you all for years!

My first interest lay there with Aaron's schematic, this is how I found this place.

I also saw that Aaron had made some comment about his inverter, but after going back through the forum later I could not find it. Anyway that post had to do with his schematic being properly configured and how he had taken 1000 volts.

I added this myself to discover that he did not take 1000.

68uF
25v
68uF
25v
10ohm
5watt
10ohm
5watt
180ohm
1watt
180ohm
1watt
154 silicon diode, that's why they mark them like this, no volts, no nothing, just nothing but a number
154 silicon diode
60v 2N3055 transistor
+ 60v 2N3055 transistor
-------------------------------------
= 1006
-24v for the transformer. You must deduct for transformers, these are all volts, no impedance.Its O.K. if you don't deduct it for your circuit but be sure you remember yourself what it is going to do to the final.

I've edited this post several times, but want to recant this -24. I don't really think a transformer this small is needing 24 volts to power up since there isn't anything impeding it, so I'll go -2v on this, so.
= 1006
-2
---------
= 1004 volts that Aaron took, and with his caps rated at 60v this is a meteor shower.

---------------------old post below---------------------------------
___________
= 982 I get 982, This could be good reason why it doesn't work. Even if it had been 1006 this is not 1000 and those 6 volts could be the difference. In reality 1 volt over just a few seconds can be like driving a locomotive through your living room and over the top of your circuit, leaving it totally fried.
-------------------------old post above-----------------------------

O.K. thanks for the legend of Aaron's schematic. I really had a great time reading through all of this.

I am going to begin drawing my own inverter circuit in a day or so when my new volt meter arrives. Maybe I too can get some help from audioguru.

Edited by - dimestone on Apr 26 2009 01:16:17 AM
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dimestone
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Posted - Apr 24 2009 :  10:09:30 PM  Show Profile  Visit dimestone's Homepage  Send dimestone an AOL message  Send dimestone an ICQ Message  Click to see dimestone's MSN Messenger address  Send dimestone a Yahoo! Message  Reply with Quote
If ever you find yourself making to many volts at or near MOSFETS you can make the circuits wider and you will correspondingly lower the resistance and lower the voltage. Fatter circuits will do this. You may also raise the voltage and the resistance by making the circuits narrower. If the circuit is designed perfectly to begin with, these things won't matter, but doing so takes some math and more time to figure the correct corresponding size. See this link to read all about it, http://en.wikipedia.org/wiki/MOSFET . The equations to do this are within this link, I think we would all need to study that a bit, but mainly using components in the sizes that we can work with ourselves, just remember you can add a little circuit wire in between the MOSFETS or take a little out to get it just right.


For the real deal that we are all trying to get at Absolutely positively go here now and read this , you will need to copy and past this entire link into your browser because this message board cannot inlcude the entire link http://en.wikipedia.org/wiki/Inverter_(electrical)

Edited by - dimestone on Apr 25 2009 06:16:22 AM
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dimestone
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Posted - Apr 25 2009 :  12:42:24 AM  Show Profile  Visit dimestone's Homepage  Send dimestone an AOL message  Send dimestone an ICQ Message  Click to see dimestone's MSN Messenger address  Send dimestone a Yahoo! Message  Reply with Quote
Hope you don't mind Aaron, I just want to see if this is a fix for this.

Do be considering an option like this http://www.crutchfield.com/p_220ADC120/Audiovox-ADC120.html?search=power+inverter if it is going to cost you less, this one is $19.99 US. I can tell you right off that the 4 capacitors that are selected for you to use already puts the total at $19. Use an alteranative that you think is best if it comes down to that for you.



Try this revision of Aaron's schematic instead, with better results I hope. I am not going to make this, not anytime soon, but if some of you have most of the stuff all we are talking about is 4 more capacitors and 4 more resistors. All in all, this circuit has 2 more capacitors and 2 more resistors thrown into the circuit, should be a breeze for those that already have the stuff. The new parts list is below the image of this new circuit.



Download Attachment: inverter3.GIF
12.42 KB


Part Total Qty. Description Substitutions
C1, C2 , C3 , C4 4 33 uf, 16 V Tantalum Capacitor , the other capacitor selection was 68uf , 25v , but we shouldn't use capacitors rated higher than the circuit we are making. Here is a manufacturers part number for the new capacitors Available Alternate Packaging T520V336M016ATE045. http://www.digi-key.com this is the digi-key part number 399-4738-2-ND if you want a 1000 of them, but this is the one you can buy individually 399-4738-1-ND.
R1, R2 2 10 Ohm, 5 Watt Resistor
R3, R4 2 150 Ohm, .5 Watt Resistor Available at http://www.radioshack.com Catalog #: 271-1109 . Note these are 1/2 watt rated
R5, R6 2 22 Ohm, .5 Watt Resistor Available at http://www.radioshack.com Catalog #: 271-1103. Note these are 1/2 watt rated
D1, D2 2 HEP 154 Silicon Diode
Q1, Q2 2 2N3055 NPN Transistor (see "Notes")
T1 1 24V, Center Tapped Transformer (see "Notes") I don't know try it without the transformer and see what happens
MISC 1 Wire, Case, Receptical (For Output)


Thank you Aaron and all for all the inspirations to do this, I hope it works! Don't forget to tell me what you think?


Edited by - dimestone on Apr 26 2009 3:10:46 PM
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pebe
Nobel Prize Winner

United Kingdom
1078 Posts

Posted - Apr 25 2009 :  05:14:34 AM  Show Profile  Reply with Quote
That still won't work.

The original circuit is crap and Aaaron should have withdrawn it ages ago. Timkering with it won't help.
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dimestone
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6 Posts

Posted - Apr 25 2009 :  06:28:38 AM  Show Profile  Visit dimestone's Homepage  Send dimestone an AOL message  Send dimestone an ICQ Message  Click to see dimestone's MSN Messenger address  Send dimestone a Yahoo! Message  Reply with Quote
quote:
Originally posted by pebe

That still won't work.

The original circuit is crap and Aaaron should have withdrawn it ages ago. Timkering with it won't help.




Care to explain why you won't work and just came across an extra $25. When in ancient rome I can let you starve to death, but you don't work so you're in the throst. This is a working circuit, post your youtube video of it doing its job well, or otherwise figure on 5 more years of you never getting with it. Don't Timker with anything just do it. Anyone else here that wants to make oppositions to something should express themselves with actions of kind heart. :b hehe
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Apr 25 2009 :  10:02:40 AM  Show Profile  Reply with Quote
Hi Dimestone,
Your circuit will not work:
1) The collectors of the transistors do not have a a DC connection to the transformer so they will not do anything.
2) Capacitors C1 and C2 still have backwards polarity.
3) R3 and R4 still do not provide the transistors with enough base current.
4) D1 and D2 will short-circuit the transformer when the voltage at each end tries to rise to +23V.
5) R5 and R6 make no sense and would just reduce the current from Q2.
6) The voltage rating of your capacitors is too low. In the original project capacitors C1 and C2 charge to about 23V. Use 50V capacitors.
5)
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dimestone
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USA
6 Posts

Posted - Apr 26 2009 :  02:20:46 AM  Show Profile  Visit dimestone's Homepage  Send dimestone an AOL message  Send dimestone an ICQ Message  Click to see dimestone's MSN Messenger address  Send dimestone a Yahoo! Message  Reply with Quote
Reply to Admin audioguru

Hi Dimestone,
Your circuit will not work:
1) The collectors of the transistors do not have a a DC connection to the transformer so they will not do anything.

Reply
This is a complete circuit doing work, maybe no useful work until it is put to its intended use of AC power production.


2) Capacitors C1 and C2 still have backwards polarity.

Oddly enough, in a Greinacher multiplier, Crofton/Walton, or cascade multiplier, here is a Marx Generator which is same http://www.instructables.com/id/High_Voltage_Power_Supply_For_Marx_Generator/ AC to DC, DC multiplier the polarity is such that the hot wire of the AC input power passes from the positive side of the Capacitor down the cascade and the reverse flow of the AC current is hindered by the diode arrangement, the neutral side of the AC power input acts as the dc negative or ground. All my head can rap around after building one of these and using it is that in making a dc to ac inverter is that it doesn't matter so long as it is 60 cycles/sec to and fro here in North America.

This is an excerpt from the Wiki on inverters electrical from my previous post, Aaron's attempt to make a more sinusoidal wave form is mentioned in the article falling under the section 'Advanced Designs', the section is just below.

Multilevel inverters provide another approach to harmonic cancellation. Multilevel inverters provide an output waveform that exhibits multiple steps at several voltage levels. For example, it is possible to produce a more sinusoidal wave by having split-rail direct current inputs at two voltages, or positive and negative inputs with a central ground. By connecting the inverter output terminals in sequence between the positive rail and ground, the positive rail and the negative rail, the ground rail and the negative rail, then both to the ground rail, a stepped waveform is generated at the inverter output. This is an example of a three level inverter: the two voltages and ground. [3]


It is also mention in the the article that, "after current passes a capacitor all previous waveforms are canceled."


Beyond this here a few more to look at?








Below :Positive flow resistance variance electron flow resistor diodes




This one I named after audioguru, Are we there yet? hot potato cold potato. Are we ready for a new component list, do we need one, do you have some nice software? I have free nationwide calling including Canada and Mexico?


Here's what I'm after?




Here are some pictures of the circuit above, but in its real built state, with a few discrepancies, I'll try it all before it's over. It didn't work, it didn't do anything, more importantly it did not blow up anything. As of yet I did not try to take a voltage reading after the two power related diodes, it was raining last night and didn't want to push my luck more than yet. Yes though, last night I did have a diode in place after the collectors on the ground side at the copper strips I'm using for circuit material.








If I do the schematic at bottom of this thread but use these 220uF 400v photo capacitors, where do you think we will be? but but wait there's more audioguru check this http://www.electro-tech-online.com/alternative-energy/86777-grid-tie-inverter-schematic-3.html this guy is offering up free info at this other board on how to build grid tie inverters, he said he is putting together some DIY cd's showing how to do his grid tie inverters. The info he offered up is later on in that grid tie inverter forum. IDK, maybe you've see it already, but still cool none the less.



$19.95, it's no wonder, a capacitor and toothpic!


3) R3 and R4 still do not provide the transistors with enough base current.


I don't know about your battery, my batter has 7800 Watts stored. 12v and 650 amps on demand.

We are starting out with 650 cranking amps in a lot of batteries, I have read manuals for several dc to ac power inverters and have discovered that they start out with a draw of only 380 miliamps.

Starting with 12v and taking a path through these resistors I get using I=E/R I=12v/10ohm I=1.2 amps, I'm not saying that this is the only path that positive electron flow will occur.


4) D1 and D2 will short-circuit the transformer when the voltage at each end tries to rise to +23V.


What voltage would that be? This is a DC circuit, would you be making a reference to AC electricity that will have almost zero potential when dealing with a silicon diode.


5) R5 and R6 make no sense and would just reduce the current from Q2.

This circuit won't wait for these little guys, but somehow man does make the universe try to conform as to be of some use. If you want to, you can try and find another similarly rated component to do the job, if there is a such an animal. I took a 1000, what will you take, I suggest 1200, 1400, 1700, 2000, maybe 4700, 7000, 10000, 11000, none of that is proven though till we try.


6) The voltage rating of your capacitors is too low. In the original project capacitors C1 and C2 charge to about 23V. Use 50V capacitors.
Yes, there were two capacitors in Aaron's shematic, they were both rated at 60v. Let's see 60+60=120, I have provided 4 capacitors rated at 33v, so 33+33+33+33=132, I have more volts.



Using Ohm's law given half the resistance across the circuit and the circuit joined with every component of this circuit, this model shows above 50 volts.

Voltage 12 volts
Current 1.2 amps
Resistance 1 10 ohms
Power 14.4 watts

Voltage 46.475800154489 volts
Current 0.30983866769659335 amps
Resistance 2 150 ohms
Power 14.4 watts


Voltage 48 volts
Current 0.3 amps
Resistance 1+2 160 ohms
Power 14.4 watts

Voltage 51.1937496184837 volts
Current 0.28128433856309726 amps
Resistance1+2+3 182 ohms
Power 14.4 watts






5)

Besides jumping from an airplane, is there anything else? If it wasn't addressed you shouldn't mention it cause I'm on a tight budget here.


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Edited by - dimestone on May 06 2009 08:26:47 AM
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Apr 26 2009 :  09:57:53 AM  Show Profile  Reply with Quote
I copied a transistor multivibrator circuit that blinks LEDs. Its supply voltage is limited to 5V to avoid avalanche breakdown of the emitter-base junctions of its transistors . Thier emitter-base junctions have a max allowed voltage of 5V.

The 2N3055 power transistors in this inverter project have a max allowed emitter-base voltage of 7V so in my second schematic I added diodes in series with the emitters.

In my third schematic I have this inverter with diodes added in series with the emitters and protection diodes added differently to the collectors of the transistors.
The base current is only (12V - 0.8V)/180 ohms= 62mA. A 2N3055 transistor saturates pretty well if its collector current is 2A when its base current is only 62mA. Then the power from the battery is 12V x 2A= 24W and the output power from the inverter is a little less.

The 2N3055 transistors need driver transistors.

Download Attachment: inverter circuit.PNG
18.66 KB

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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Apr 26 2009 :  4:41:59 PM  Show Profile  Reply with Quote
Hi Dimestone,
Nobody sees anything good about your modifications that won't work.

This project was probably started about 50 years ago but used PNP germanium transistors which explains the backwards capacitors. Germanium transistors did not have a low voltage emitter-base avalanche breakdown.
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Apr 26 2009 :  6:03:14 PM  Show Profile  Reply with Quote
Hi Dimestone,
Never mind changing this hopeless inverter circuit around. If it is fixed then its output power is very low.
This is how it will work if it is fixed:

Download Attachment: inverter circuit again and again.PNG
19.41 KB

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dimestone
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Posted - Apr 27 2009 :  04:41:34 AM  Show Profile  Visit dimestone's Homepage  Send dimestone an AOL message  Send dimestone an ICQ Message  Click to see dimestone's MSN Messenger address  Send dimestone a Yahoo! Message  Reply with Quote
quote:
Originally posted by audioguru

Hi Dimestone,
Never mind changing this hopeless inverter circuit around. If it is fixed then its output power is very low.
This is how it will work if it is fixed:

Download Attachment: inverter circuit again and again.PNG
19.41 KB







My momma told me since I can remember that I was the "Icing on the cake." I'm building a prototype at the moment, I have to let the iron warm up.
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Justinjustin
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Posted - May 18 2009 :  05:13:45 AM  Show Profile  Reply with Quote
quote:
Originally posted by audioguru

Hi Kennedy,
That 500W inverter had many mistakes. I fixed it two years ago but a moderator there recently changed it so it doesn't work any more. Here is my fixed one. For 1000W it needs many more transistors and 100A from the 12V battery. Its output is a square-wave.

Download Attachment: 500Watts_Inverter-small.PNG
161.27 KB






Hi, audio Guru,
this is the one I am using, I want to know the VArating of the transformer. and Can transformer use reverse?
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - May 18 2009 :  6:38:27 PM  Show Profile  Reply with Quote
That is a very old inverter that was originally designed in China.
It uses many old 2N3055 transistors because modern Mosfets were not available there.
I fixed it so that it could be used in The Philippines where poor people do not have any electricity.

It has a square-wave output. Many electronic products do not work properly with a square-wave.

Sometimes a transformer can be used in reverse if it has enough inductance.

The output power is 500W so the transformer should be 600VA.

It was recently improved with a zener diode and a change in the transformer voltage.

Download Attachment: 500w inverter final again.PNG
151.1 KB

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