Need Inverter Ckt

Kermit2

Joined Feb 5, 2010
4,162
People who 'want to make it' themselves, are usually equipped with knowledge, parts and tools needed to do the job.

You don't appear to have very many of the items that you need to do it yourself.

Besides your questions about HOW to do it, what else do you have that you think makes you able to do this task on your own?
 

retched

Joined Dec 5, 2009
5,207
I have tried and tried.

There are no pure sinewive inverters of ANY wattage.. not 1 watt, 10 watts or 100 watts. thay contain no ICs.

Pure Sinewave "creation" and amplification in a solidstate environment requires some serious computing power.

You COULD convert an IC to just transistors and such, but the 1000 or so transistors in one of these ICs would take you MONTHS to put together.

And with no oscilloscope and steady power supply to run it, this is a lost cause.

How will you know if you are doing correct adjustments or not?

With no oscilloscope, you cannot see the waveform.

If you slowed it to an audible frequency to try to listen to it, you would not be able to distinguish a well done PWMed "modified" sine wave, or a true sine wave.

People have posted inverters for you.

Give them a try.

Read the schematic, see the ICs you need, and start asking friends and family is anyone they know has a repair shop or electronics hobby that may be able to get the ICs you need to complete the project.

Buying 500 dollars worth of transistors to make a 50 cent IC makes no sense.. And would require more talent and knowledge than most people on this forum contain.

You must network to find these ICs.

If you have friends online, ask one to mail you the ICs you need.

Is there any broken UPS or inverters that you can get parts from?
Think about all the ways you can ask people to help get you these parts.

If you DO build one, and It works, you will have NO PROBLEM finding customers for it.

You just need to get started.

You haven't given up yet, so maybe you will find a way to succeed.

BUT, you really need ICs.

Good Luck.
 

Wendy

Joined Mar 24, 2008
23,415
Several issues involved, most involve the transformer. 100W means around 10A from the battery load, probably more.

I started a thread on this subject, then got sidetracked. These things come in waves.

AC/DC Inverters

Guess I need to finish it. I got sidetracked trying to figure out a simple freq calibration circuit.

The simple fact is you can buy a unit like this much cheaper than you can build. Anyone who says anything different is guilty of wishful thinking.
 

thatoneguy

Joined Feb 19, 2009
6,359
Can you get MOSFETs?

Can you get a PICKit 2 and a microcontroller?

Do you already have the transformer?

Sine wave output of an inverter isn't possible, unless you create a 100W Linear amplifier having + and - 180V rails, then make the input a sine wave. An extremely good approximation of a sine output can be done with the "magic sine" PWM algorithm, which needs either a microcontroller or a lot of different logic ICs.

You won't be able to get sine output with only BJT Transistors and a "simple" circuit. You will need ICs, preferably a microcontroller.

What in the above list do you understand, and what parts can you get/do you have?
 

Wendy

Joined Mar 24, 2008
23,415
You could, if you don't mind square waves. I would go with a couple of MOSFETs because of the current requirements.

There are a lot of transistorized sine wave generator designs though, it could be done. The core problem is knowledge base, we have a beginner trying an advanced project, and chips (even simple chips) simplify the job enormously.

I plan on showing a simple sine wave inverter eventually.
 

Audioguru

Joined Dec 20, 2007
11,248
I think we already did, about as basic as you can get, just change the transformer.

http://www.aaroncake.net/circuits/inverter.asp?showcomments=all
But this inverter doesn't work. It is too simple to work.
Its transistors have avalanche breakdown of their emitter-base junctions.
The fairly high avalanche current in the capacitors causes them to blow up.
The base current of the transistors is low so their output current is low.
The max output is 25W if you are lucky in about a 50V square-wave.
 

marshallf3

Joined Jul 26, 2010
2,358
I've made something very similar work ages ago but obviously don't have the book nor the circuit anymore, would you like to take a try at designing a simple multivibrator circuit that can oscillate around 50 Hz and drive a 24VCT transformer?
 

debe

Joined Sep 21, 2010
1,389
Has any one seen a circuit of whats in a Digital sine wave Genny now that would be interesting. All ive got is this, but whats in the inverter part, a replacement is almost as expensive as buying a whole Genny.
 

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kubeek

Joined Sep 20, 2005
5,794
Sine wave output of an inverter isn't possible, unless you create a 100W Linear amplifier having + and - 180V rails, then make the input a sine wave.
Just an idea, what about using 50hz sinewave oscillator and feeding this to a simple half-bridge PWM? That should generate true sinewave if I am not mistaken.
 

kubeek

Joined Sep 20, 2005
5,794
This is a pretty good guide, with the only difference that it will be driving a step-up transformer and not a speaker.

I just remembered that I have an old UPS transformer at home, so I could try making my own :)
 

retched

Joined Dec 5, 2009
5,207
you provided such a complex ckt diagram!
Inverting to true sine wave is COMPLEX. That is why it is such a complex circuit diagram.

It doesn't matter if it is 50 watts or 50,000 watts. The basic inverter circuit will be the same.

You will just have a larger transformer and MORE transistors to handle the output wattage.
 

Wendy

Joined Mar 24, 2008
23,415
Which is what most of us have been saying from square one. A professionally made unit is much cheaper than anything you can make. People assume they are simple for some reason. The simple designs do not work well, and it still does not mean you can build it cheaply, or cheaper than a store bought unit.

Then you add things like "no ICs" and expect that to be practical. It isn't. The ICs do not have to be as custom as some people imply, but there is a reason ICs exist, they do the job of many transistors.

Just curious, did you even look at the link I pointed to on post #44? It was a tutorial on how to build them, along with an explanation why it wasn't necessarily a good idea. While it isn't finished, it did have schematics.
 
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