Low-pass Filter?

[audioguru2]

Connect parts to protect the CD4047 like this:

View attachment 38609

 

[indulis]

This uses a push-pull topology, so only one half of the primary is active at any point in time. Each half winding has 12V across it relative to the center-tap. Through flyback action, the opposite winding end will have 2 times the input voltage when the switching element on side that's being measured is switched off. This is the reason push-pull primary switching elements have to have a voltage rating of at least 2X Vin. If your measuring 24VAC, your measuring from gnd to one end of the transformer primary winding.

 

[ray99mond]

audioguru
thanks a lot, I'll try again

 

[agfsession]

Hello, i have seen you proyect, and i would like to know if the IC is only to make a square wave (and the negated) to control the two LM358?
what level of signal is at the output of Q and /Q? could it be maded with a simple n555,R and C circuit?
What will happend if i set to the LM358 a  sinusoidal signal?coult it generate a SIN signal at the transformer?or does it work as a comparator and it gets 12 - 0 - 12 - 0 (Q=1, Q=0, Q=1, Q=0)?
and what about to set the Sinsuidal generator after LM358 and driving the MOSFETs?The Sinusoidal must make only one Pi ,i mean  PI=3'14,the half of the period, to generate a half wave each time with each LM358

Thank you Very Much. Great proyect

 

[audioguru2]

Hello, i have seen you proyect, and i would like to know if the IC is only to make a square wave (and the negated) to control the two LM358?

Yes, the CD4047 has a frequency divider so its outputs are a perfect square wave.

what level of signal is at the output of Q and /Q? could it be maded with a simple n555,R and C circuit?

The CD4047 is Cmos so with its very light load its output voltage swing is the supply voltage.
A 555 doesn't make a perfect square wave. The CD4047 circuit is perfect, simple and cheap.

What will happend if i set to the LM358 a

 

[agfsession]

Hello and Thanks, now i have the question, you said some replies up, you will not use to give power to a computer, because it needs a sin wave, then if the effective value for a wave is ->  Vf / (2^(0'5) and 220V/(2^(0'5) = 156 V

if you use a Transformer 12 - 0 - 12 To 156 will be usefull, isn't it?

 

[audioguru2]

Don't make an inverter with the wrong output voltage so that the peak of its square wave is the same voltage as the peak of a sine wave. If it powered heaters or lights then they would have way too much voltage.

 

[agfsession]

OK thank you very much.

 

[anton12]

hi
can i use tip142 for the darlington pair in 500wat inverter to rdive 2n3055s

 

[audioguru2]

can i use tip142 for the darlington pair in 500wat inverter to rdive 2n3055s?

Then you might need to select them for high gain and also select 2N3055 transistors for high gain.

With a 500W load, the battery current is 50A. Therefore the 4 sets of output transistors pass 12.5A for each transistor. The minimum current gain for a 2N3055 is 5 with a 10A collector current so might be only 4 with 12.5A. Therefore the total base current for 4 output transistors could be as high as 12.5A.
The TIP142 isn't spec'd with a 12.5A load and its minimum gain is not high enough and its saturation voltage is poor at only 10A.

 

[faizanbrohi]

Now Can we use a Sine wave oscillator instead of a square wave osicllator , this would increase performance for runnning systems that need sine waves ..

???

 

[audioguru2]

Now Can we use a Sine wave oscillator instead of a square wave osicllator , this would increase performance for runnning systems that need sine waves?

Are you talking about a power inverter?
What about the heat?
In a square-wave inverter, the output transistors alternately switch fully on or fully off to reduce power wasted as heat. A good inverter using transistors is about 80% efficient and one using Mosfets is about 90% efficient. So to produce 1000W output the Mosfet one would heat with only 110W and draw 92.5A from a 12V battery.
A simple sine-wave inverter is just a linear audio amplifier. The output transistors are conducting all the time and therefore waste a lot of power as heat. It would be about only 50% efficient. So to produce 1000W output it would heat with 1000W and melt, and draw 166.7A from a 12V battery.

A Class-D audio amplifier uses Pulse-Width-Modulation so that its output transistors can switch fully on and fully off and remain fairly cool, but still produce a low frequency sine-wave. It would make a good sine-wave inverter but is complicated.

 

[faizanbrohi]

Forget about the complication , how can we paractically implement it in Class D amplifier , and if not , can we run computer on a square wave

 

[faizanbrohi]

One more thing , can not we change the wave shape of square wave 220V AC to sin ewave

 

[audioguru2]

There are many high power Class-D audio amplifiers available.

I don't think a computer's power supply works with a square-wave mains.

A "ferro-resonant" transformer has an additional winding that is tuned with a capacitor so a square-wave input makes a sine-wave output. Its core saturates in order to regulate the output voltage.
If you tune an ordinary transformer then its output voltage will change when the load changes.

 

[faizanbrohi]

so for a class D Amplfier we would consider increasing the current first , as it is done in this project.and then add a transformer , or vice versa

 

[audioguru2]

You could use a low voltage, high current Class-D amplifier to drive an ordinary power transformer in reverse to stepup the voltage.
You could use a high frequency oscillator to drive a small stepup transformer, rectify its high voltage then use the DC for a high voltage Class-D amplifier.

Either way is complicated. The highest power from an IC that I have seen is only 240W.

 

[faizanbrohi]

So increase the number of channels per output .

 

[faizanbrohi]

And we can also cascade it

 

[wsg]

1. I don't understent how many LM358 should I use in this circuitry? (about 100W inverter?)
2. May i test this scheme without transformer or with small trasformer without load just for test?
3. Some one have compete PCB for 100W inverter?