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 12/120V inverter again
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Aaron Cake
Administrator

Canada
6702 Posts

Posted - Feb 19 2011 :  10:26:32 AM  Show Profile  Visit Aaron Cake's Homepage  Send Aaron Cake an ICQ Message  Send Aaron Cake a Yahoo! Message  Reply with Quote
Why don't you read through the topic and look at all the circuits posted? The hardest part is going to not be the driver circuit (many examples in this thread) butthe custom 1:2 transformer. Probably start with a huge microwave transformer and wind on a new secondary.
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Waqas
New Member

2 Posts

Posted - Apr 07 2011 :  06:27:42 AM  Show Profile  Visit Waqas's Homepage  Click to see Waqas's MSN Messenger address  Send Waqas a Yahoo! Message  Reply with Quote
Please tell me how can i make a simple 50Hz 220v suply with 12V battery

Waqas
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Apr 07 2011 :  6:59:47 PM  Show Profile  Reply with Quote
Simple means very poor performance or no performance.
A simple inverter can light an incandescent light bulb or heater.
But many electronic products won't work.

Where will you buy a powerful deep discharge battery? A car battery is designed to deliver very high current for a few seconds and will be destroyed if it is used to power an inverter.
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Aaron Cake
Administrator

Canada
6702 Posts

Posted - Apr 09 2011 :  10:26:57 AM  Show Profile  Visit Aaron Cake's Homepage  Send Aaron Cake an ICQ Message  Send Aaron Cake a Yahoo! Message  Reply with Quote
quote:
Originally posted by Waqas

Please tell me how can i make a simple 50Hz 220v suply with 12V battery



If you review this topic in which you just posted, you will see many such schematics have been posted already. That's why this topic is a sticky topic; because inverter questions come up all the time.
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vinu673
New Member

India
3 Posts

Posted - Jun 14 2011 :  07:39:28 AM  Show Profile  Reply with Quote
is 110v dc 230v ac inverter is possible with a current control on input side?
pl help
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vinu673
New Member

India
3 Posts

Posted - Jun 14 2011 :  07:41:53 AM  Show Profile  Reply with Quote
1500-2000 w power?
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Aaron Cake
Administrator

Canada
6702 Posts

Posted - Jun 18 2011 :  10:25:47 AM  Show Profile  Visit Aaron Cake's Homepage  Send Aaron Cake an ICQ Message  Send Aaron Cake a Yahoo! Message  Reply with Quote
Not with the schematic shown on the inverter page. There are several schematics posted in this thread which could handle that much power but the output section and transformer would be huge. An inverter in the 2KW range really should be a switching supply, and such a power supply isn't made from commonly available parts.
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Ferraro1
New Member

USA
1 Posts

Posted - Jul 27 2011 :  02:59:29 AM  Show Profile  Reply with Quote
AH! But this circuit does work!!! I am having some problems with frequency here, so I will attempt to alter the RC network a little. Tantalum capacitors are hard to find in the denominations were using here, might have to parallel a bunch up. I do see the reason for tantalum caps here, at the cost of several electrolytic explosions. :) I did scope the output on a digital o scope and there sure is a bunch of high frequency crap, might try a little low-pass and see if I can't reject some of it. Wanted to mention also that I wired a 12.6V CT XFMR rather than the 24v as shown, and of course at the cost of output current, but with the 3055 nPn s I'm using it could be upgraded easily with either a hand wound XFMR or a salvaged one. I'll let you know just how much I can push out, also consider using an in line fuse here. Thanks for thus we're going to go with a solar application for this.
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Jul 28 2011 :  08:09:21 AM  Show Profile  Reply with Quote
The capacitors blow up because they have the very high current of the transistors having avalanche breakdown of their emitter-base reverse biased junctions in them. The avalanche breakdown causes most of the power to be wasted (which blows the capacitors) so the remaining output power is very low. The transistors have a forward base current that is too low to make much power anyway.

Silicon transistors should never be used in this multvibrator circuit when the supply is higher than 7V to eliminate avalanche breakdown (or maybe re-designed with extra diodes). Maybe this circuit originally used old germanium transistors.
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pebe
Nobel Prize Winner

United Kingdom
1078 Posts

Posted - Jul 28 2011 :  12:55:52 PM  Show Profile  Reply with Quote
quote:
Tantalum capacitors are hard to find in the denominations were using here, might have to parallel a bunch up. I do see the reason for tantalum caps here, at the cost of several electrolytic explosions
I have found tantalums available up to 200uF. But tants are polarized, so what makes you think they will stand reverse voltage better than electrolytics?
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Aug 22 2011 :  2:51:01 PM  Show Profile  Reply with Quote
The polarity of the capacitors has been recently corrected on the schematic.
Their polarity is reversed only about 0.6V which will not damage an electrolytic capacitor.

But there is a very high current in the capacitors that damages them. One capacitor is charged to about 24V (transformer action causes a transistor collector to swing to +24V) then this transistor turns on and its collector saturates and drives the positive end close to ground which tries to drive the negative end to -24V. But the emitter-base junction of this transistor has avalanche breakdown (like an 8V zener diode) at a high current. The high current is in the capacitor.

The avalanche breakdown of the emitter-base junctions can be prevented by adding diodes in series with each base. Then each base will need a 2.2k resistor to ground to make it turn off when it should be turned off.
The timing will need to be re-adjusted.
The base current is low so the output power will be low.

Download Attachment: bad inverter corrected.PNG
6.96 KB

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JUAN DELA CRUZ
Mad Scientist

Philippines
476 Posts

Posted - Aug 23 2011 :  06:05:16 AM  Show Profile  Reply with Quote
@audioguru

Hi audioguru! Its been a long time :-)

Do the inverter circuit above (with the correction) is functioning now?

How much power it can provide from a 100AH car battery?

juan dela cruz
Penniless INVENTOR
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Aug 23 2011 :  11:26:27 PM  Show Profile  Reply with Quote
Hi again, Juan.
My corrections to the inverter will result in a base current of only about 66mA. Then the transistor collector current will be only 660mA if the transistors have minimum current gain when saturated.
660mA at 120VAC output is a power of only 79.2W. Some transistors with a high current gain might provide an output power of 158W.

The extremely simple circuit produces a square-wave output that many electronic devices cannot use.
Its output voltage is not regulated so it is too high with a freshly charged battery and light load and is too low when the battery is running down and the load is heavy.
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JUAN DELA CRUZ
Mad Scientist

Philippines
476 Posts

Posted - Sep 01 2011 :  1:35:22 PM  Show Profile  Reply with Quote
Well it is a good choice for low power application where in voltage regulation is not the priority.

BTW, what is transistor that can be use to increase its output power a little bit? (that you have mentioned with High Gain?)


Thanks audioguru

juan dela cruz
Penniless INVENTOR
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Sep 02 2011 :  09:28:36 AM  Show Profile  Reply with Quote
quote:
Originally posted by JUAN DELA CRUZ
BTW, what is transistor that can be use to increase its output power a little bit? (that you have mentioned with High Gain?)

Hi Juan,
Inverters used power transistors many years ago. Today they use a little oscillator that drives power Mosfets.
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