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# DC to AC

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Dears,

What is the usual technique employed in converting the DC to AC (50Hz); as in case of a simple voltage AC inverter.

Vivekanand

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Our simple 500W inverter project has a square-wave output that has the same effective power as a sine-wave.
http://www.electronics-lab.com/projects/power/033/index.html

It uses an IC to make two 50Hz signals, one is the opposite phase of the other. Then the circuit uses a couple of opamps and a bunch of transistors to amplify the current from the oscillator up to 50A. The transistors drive a 12V-0-12V transformer backwards so it increases the voltage up to mains level. If available, 2 or 4 Mosfets can replace all those transistors.

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i.e. 4047 produces 2 square wave ACs and you are amplifying it by op-amps and further by set of transistors. and finally feeding it to a 12-0-12 to 220-0 transformer.

My question : Is there any IC which produces sinewave signals (2 sets opposite in phase to each other)?

What is the difference in using this type of inverter compared with the sine-one?

What if I use 555 and amplify using the same topology and finally feeding it to a 12-0 to 220-0 type transformer?

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Is there any IC which produces sinewave signals (2 sets opposite in phase to each other)?

No, but the transistors would melt if they were fed a sine-wave anyway. The transistors switch fully on (low voltage so low heating) and fully off (no current so no heating) with a square-wave. A linear sine-wave would keep them conducting near halfway all the time and make them extremely hot. Also, a linear sine-wave inverter would use more battery current than a square-wave inverter.
A sine-wave can be made with high frequency Pulse-Width-Modulation to make an efficient sine-wave inverter.

What is the difference in using this type of inverter compared with the sine-one?

Some motor speed controls don't work with a square-wave. Most electronic products receive a voltage that is too low. Multi-voltage radios and TVs, and lights and heaters are fine with a square-wave.

What if I use 555 and amplify using the same topology and finally feeding it to a 12-0 to 220-0 type transformer?

A 555 uses more parts and costs much more than a CD4047. The signal to the transformer would be pulsing DC instead of AC causing the transformer to saturate if it is loaded. The transistors operate only half the time. The output power would be about 1/4 or less the power rating of the transformer.
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Ok...

For a general purpose lighting inverter, is the model with IC NE555 be useful?

The technique will be:
IC 555--->Square Wave AC---->Amplify------>Transformer---->output.

Will it work this way?

Which one do you prefer, 12-0-12 to 220-0 (backwards) or 0-12 to 220-0 (backwards) for this case?

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For a general purpose lighting inverter, is the model with IC NE555 be useful?

The technique will be:
IC 555--->Square Wave AC---->Amplify------>Transformer---->output.

Will it work this way?

Which one do you prefer, 12-0-12 to 220-0 (backwards) or 0-12 to 220-0 (backwards) for this case?

The 555 doesn't make AC, it makes pulsing DC. A coupling capacitor can feed an ordinary transformer winding from a complementary push-pull output circuit.
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I got it..

Really I was confused with monostable of 555.

Is the 4047 the only wat to make it? I mean are there any other techniques to produce AC, using transistors, etc.?

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Really I was confused with monostable of 555.

A 555 astable oscillator makes nearly a square-wave. With more resistors and a diode then the output can be adjusted to be a perfect square-wave.

Is the 4047 the only wat to make it? I mean are there any other techniques to produce AC, using transistors, etc.?

The 4047 needs only a single resistor and a single capacitor to make a perfect square-wave and its opposite phase.
There are lots of circuits that make nearly a square-wave but they use lots of parts.
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Is the 4047 the only wat to make it? I mean are there any other techniques to produce AC, using transistors, etc.?

Many designs use Buffers, many use Inverters (NOT gates) to produce a nice square wave. I have also seen AND and NAND gates used to do this. Digital gates are good for providing a square wave. In fact, many circuit designs employ them to square up other wave forms that are not clean enough for a good digital switching action. The nice thing about using digital gates is that they have a good fan-out. Thus, you can parallel and/or series them to get a stronger signal if ever needed.

MP
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Many designs use Buffers, many use Inverters (NOT gates) to produce a nice square wave. I have also seen AND and NAND gates used to do this.

Aren't we talking about an power inverter circuit, not just any oscillator?
Their waveform isn't a perfect square-wave. It is "squared" but is not 50-50 duty-cycle.

A 4047 oscillator makes a "squared-wave" signal like those others then divides it by 2 with a flip-flop so its outputs are exactly a square-wave, with a perfect 50-50 duty cycle. With just a single resistor and a single capacitor to set the frequency.
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Aren't we talking about an power inverter circuit, not just any oscillator?

Yes. I thought my answer was pretty clear in that regard.

MP
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Ok.....

What is the maximum input(DCV) and output (ACV) voltage and amperage of this 4047?

What is the exact "design difference" between of UPS and an inverter?

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What is the maximum input(DCV) and output (ACV) voltage and amperage of this 4047?

It is an ordinary Cmos logic IC. Their supply voltage range is from 3V to 18V and their output voltage goes to the supply voltage if the load current is very low. With a 13.8V supply, the max output current is about 8mA.

What is the exact "design difference" between of UPS and an inverter?

A UPS charges its batteries when power is present then automatically switches to power the load when the power fails. Then it switches back again when the power is restored.
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Ok...

In the cited design of an inverter, you have used LM358 and then the output is fed to one darlington pair and subsequent transistors. Instead, if I use a series of op-amps like LM358s, then does it work that way?

If I want to use the MOSFETs, then what are suitable substitutes?

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In the cited design of an inverter, you have used LM358 and then the output is fed to one darlington pair and subsequent transistors. Instead, if I use a series of op-amps like LM358s, then does it work that way?

A series of opamps won't do anything. Their max output current is only 20mA.

If I want to use the MOSFETs, then what are suitable substitutes?

Mosfets switch very quickly. The CD4047 or the opamp switch slower and might cause both Mosfet sides to conduct at the same time. Investigation is required.
Many things like current and heat dissipation specs and spike voltage protection must be considered when designing an inverter that uses Mosfets.
Mosfets available in my country might not be available in your country.
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A 4047 oscillator makes a "squared-wave" signal like those others then divides it by 2 with a flip-flop so its outputs are exactly a square-wave, with a perfect 50-50 duty cycle. With just a single resistor and a single capacitor to set the frequency.

There is nothing in the datasheet that proclaims a "perfect 50-50 duty cycle. In fact, the manufacturer puts a disclaimer in the data sheet that a 50% duty cycle is not guaranteed. Fortunately, for a square wave inverter, you do not need a perfect square wave. You don't even need a perfect 50 hz or 60 hz. The square wave inverters are the worst of all inverters out there. You will see a large variance from one to the other. If you want to build something that will be useful, build a sinewave inverter.

MP

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The CD4047 has 3 outputs:
1) Its oscillator output which is an ordinary Cmos oscillator and they say "a 50% duty-cycle is not guaranteed". Inverter circuits don't use it.
2) a Q output at half the oscillator frequency and they say "at 50% duty cycle".
3) A Q-not output at half the oscillator frequency and they say "at 50% duty cycle".

A flip-flop divides the oscillator so the Q and Q-not outputs have perfect 50-50 duty cycle.

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Interesting that you can read that into the data sheet when it is not there...

MP

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Interesting that you can read that into the data sheet when it is not there...

The datasheet says clearly exactly what I said. I even explained how the IC uses a digital divider to make two of its outputs perfect square-waves.
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Amazing....since I posted a picture of part of the datasheet. Where did you find the word "perfect"? I performed a search of the pdf and found 0 instances of the word "perfect". I also performed a search for the word "exactly". Also, there are 0 instances of this word. However, I do find a statement in the data sheet that says a 50% duty cycle is not guaranteed. You have a pretty good nack for reading things into a data sheet that do not exist....of course, I think I have made this same statement to you several years ago..

oh, by the way...what you explained was how the IC uses a digital divider to produce perfect compliments of the two signals Q and Q-NOT...Not how it produces perfect square waves. There is quite a difference. I know I am wasting my breath to explain all of this to you, but there are others who might like to know.

MP

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Dear MP....

What is the technique to generate a set of sinewaves (of opp phase)?

Is it the regular oscillator?

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MP,

The way I read it is that the %duty at Q and Q_bar will be 50% and that the signal at the oscillator output is not guaranteed to be 50%

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Yes, AN920. That is what it says. That is also what I said.

Also, notice in the block diagram that it uses an inverter to make the compliment, not the divider. The digital divide-by-two divider has a single output.

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I think the block diagram is a bit misleading. You get a better idea from the logic diagram which shows a combination of inverters used to obtain Q and Q_bar

Also the way they drawn it may be a way of indicating that the FF has buffered outputs. Will be difficult to tell without the details of the internals.

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Here is something interesting. I guess it depends which databook you look at

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