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 12/120V inverter again
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ogun4ever
New Member

1 Posts

Posted - May 04 2007 :  09:54:05 AM  Show Profile  Reply with Quote
pls i need dc to ac inverter of 20w
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - May 04 2007 :  12:15:35 PM  Show Profile  Reply with Quote
20W is almost nothing.
This circuit should work.

Download Attachment: 100W inverter.GIF
15.87 KB

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tmk3a014
New Member

Indonesia
1 Posts

Posted - May 10 2007 :  08:33:40 AM  Show Profile  Reply with Quote
Hi I'm sugeng I have some question and i hope some of you can help me to solve my problem,
I want to make inverter that can change 12VDC to 220VAC, please send me the diagram and tge component list. I also want to make an automatic battery charger for 12V battrey but my source is from solar cell please send me the diagram and the component list.
Thank you, my email is mulyadi_sugeng@yahoo.co.id
I hope i can have the diagram and the component list soon.
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Aaron Cake
Administrator

Canada
6702 Posts

Posted - May 10 2007 :  09:05:51 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 tmk3a014

Hi I'm sugeng I have some question and i hope some of you can help me to solve my problem,
I want to make inverter that can change 12VDC to 220VAC, please send me the diagram and tge component list.



This has been answered several times before in this thread. Just use the appropriate transformer.
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mrenjan
Apprentece

India
19 Posts

Posted - May 11 2007 :  09:11:19 AM  Show Profile  Reply with Quote
One Question to AudioGuru.. Is there any advantage of using 2N3055 instead of Mosfet's like IRF540 directly tied to CD 4047. We dont even need the OP-amps since Mosfet requires only less Drive current. Probably the only other change required is in the Transformer side (9-0-9 instead of 12-0-12). I thought the efficiancy of Mosfet is much higher than Transistor since leakage current is less. Not sure whether i am wrong.

Renjan
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - May 11 2007 :  10:08:38 AM  Show Profile  Reply with Quote
quote:
Originally posted by mrenjan

One Question to AudioGuru.. Is there any advantage of using 2N3055 instead of Mosfet's like IRF540 directly tied to CD 4047. We dont even need the OP-amps since Mosfet requires only less Drive current. Probably the only other change required is in the Transformer side (9-0-9 instead of 12-0-12). I thought the efficiancy of Mosfet is much higher than Transistor since leakage current is less. Not sure whether i am wrong.


2N3055 transistors were used in the 100W and 500W inverter because the circuit is very old and 2N3055 transistors atre available in countries that don't have Mosfets. Mosfets are much better.

The IRF540 Mosfet is also getting pretty old since much better Mosfets are available now.

The CD4047 can directly drive two Mosfets in an inverter and the output power depends on their current rating and the size of the heatsink. Cheap Chinese inverters use Mosfets.

Efficiency is determined by how much power is wasted as heat in the transistors when they conduct, not leakage current.
A 2N3055 transistor has a max saturation voltage of 3V at a collector current of 10A and a huge base current of 3.3A. That is 35W of heat for a 100W inverter.
An IRF540 Mosfet has a max saturation voltage of 0.44V at 10A so wastes only 4.4W in a 100W inverter. Better Mosfets would operate cooler and therefore the efficiency would be higher.

If you use a 9-0-9 transformer with Mosfets then with a fully charged battery at 13.8v the output voltage will be 170VAC instead of 115VAC or will be 341VAC instead of 230VAC.

If you use a 12-0-12 transformer with Mosfets and a fully charged battery then the output will be 128VAC instead of 115VAC and will be 256VAC instead of 230VAC.
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mrenjan
Apprentece

India
19 Posts

Posted - May 14 2007 :  12:17:56 AM  Show Profile  Reply with Quote
Thank you Audioguru for your time.. This is lot of good information. Can you please tell me a better Mosfet for such application ?
I thought there was a 3 V (Drain source)drop when using Mosfet (IRF 540).. So the battery voltage for 13.8 should be taken as 10.8 when doing calculation using Mosfet. Also if we use a ordinary 12-0-12 or 9-0-9 mains transformer,the losses associated also will be high since Primary and secondary is now in the reverse order. Please clarify.

Renjan

Edited by - mrenjan on May 14 2007 07:11:11 AM
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - May 14 2007 :  4:24:03 PM  Show Profile  Reply with Quote
The old IRF540 Mosfet has a drain to source max resistance of 0.044 ohms when it has at least 10V on its gatwe and it is cool.
Then its voltage drop is 0.44V at 10A and is 2.2V at 50A. 50A x 2.2V would make 110W of heat which would increase its resistance as shown on the graph in its datasheet.

There are hundreds of newer and better Mosfets. An IRF3711Z has an on-resistance of only 0.006 ohms. At 50A its voltage drop is only 0.3V.

Transformers have a max power rating. Do not allow the inverter and its load to exceed the max power rating then the loss is very low.
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mrenjan
Apprentece

India
19 Posts

Posted - May 14 2007 :  11:17:22 PM  Show Profile  Reply with Quote
Thank you Audioguru..

Renjan
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sunil_223
Apprentece

7 Posts

Posted - May 17 2007 :  09:30:27 AM  Show Profile  Reply with Quote
hi audioguru i have tried to make the inverter but it didnt work.
i am using 12/220v transformer.
68uf 16v capictor{tantlum}.
4007 diodes.
2n 3055 transistors.
180ohms 1 watt and 10ohms 5 watt resistor
but it didnt work.
only the transistors r heating up and no output is there.
please help me out.
can u tell me were i am wrong.
plz send me the schematic diagram of inverter if u have made any changes in it.
thanx
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - May 17 2007 :  11:32:31 AM  Show Profile  Reply with Quote
Hi Sunil,
The transistors in the simple inverter have avalanche breakdown if the supply voltage is more than 8V.
The capacitors are shown connected backwards.
The circuit doesn't provide enough base current for the transistors to make much power.

It has too many things wrong for me to make changes to it. It is too simple to work properly.
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sunil_223
Apprentece

7 Posts

Posted - May 18 2007 :  05:49:56 AM  Show Profile  Reply with Quote
thanx for ur reply
so audioguru have u rectified the problem?what is it can u tell me ?is it possible to make such simple inverter by making some changes in it?
waiting for reply
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sunil_223
Apprentece

7 Posts

Posted - May 18 2007 :  12:17:09 PM  Show Profile  Reply with Quote
hello audioguru
the schematic diagram for inverter on this page for 100watts is working properly?will this circuit function properly?

and what about that 500watts?shall i start making any one of them?
both r right or not?
plz reply
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - May 18 2007 :  4:22:48 PM  Show Profile  Reply with Quote
The 100W and 500W inverters have a square-wave output if your load doesn't mind.
I don't know if anybody has made the 100W one, but the 500W one works fine. The 100W one is the same but is smaller so it should also work fine.

Their capacitors are not connected backwards.
Their transistors do not have avalanche breakdown.
Their transistors have plenty of base current for a high power output.
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sunil_223
Apprentece

7 Posts

Posted - May 19 2007 :  01:58:49 AM  Show Profile  Reply with Quote
thanks audioguru
first i will try for 100w if it works then i will go for 500w
i want to know that what is the watts for R1,R2 and R3
and what is the volts for .1uF cap and power switch or relay?
i mean to say resistor R1 is 47k ohms but how many watts?
same for cap and relay.
relay is necessary for this circuit?
can u tell me what is 12-0-12v transformer?
i had purchased it.
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