The 115 volt side is in parallel and the 10 volt side in series with the center going to +12.

Got it... what if I were to use one with a 12V output instead?

 

Thanks... also, the sim is taking forever to run in LTspice

Try skip initial operating point where you set the time.
The output would be to low with a 12 volt one. The transformer voltage is RMS so the peaks are stored in the cap (1.4X RMS), but with the 12vdc it's just 12 in 115 out.

 

Try skip initial operating point where you set the time.
The output would be to low with a 12 volt one. The transformer voltage is RMS so the peaks are stored in the cap (1.4X RMS), but with the 12vdc it's just 12 in 115 out.

Alright, thanks, I think I found an exact equivalent for what you're specifying.

 

It appears that the sim is running in steps of 0.01 µs !!!!

 

The sim slows down to a crawl at exactly 8ms. I don't know LTspice that well to instruct it to skip stuff and go faster. Not familiar with directives.

 

Lets try it again.

 

Lets try it again.

There you go! it ran the sim in a snap! what did you change? I looked up the <Edit Simimulation Cmd> dialog and it looked the same

 

The sim slows down to a crawl at exactly 8ms. I don't know LTspice that well to instruct it to skip stuff and go faster. Not familiar with directives.

Try Edit, Spice analysis, then click check initial operating point Must have been a bad download.

 

I'm reading 128 mA RMS at the transformer's output (L1), while I see 1.17 A RMS at (L2) and 947 mA RMS at (L3) that's a protection of approx 2 to 1 when compared to the specs of the transformer you're suggesting, right?

 

Ooops, the 2 coils have different resistances. They should be the same. Probably doesn't matter much if it's 0.2 or 0.25, but lets make it 0.25 so we are both the same.
You probably could use a smaller one. I'm not sure if or how to derate for the square wave.

 

Ooops, the 2 coils have different resistances. They should be the same. Probably doesn't matter much if it's 0.2 or 0.25, but lets make it 0.25 so we are both the same.
You probably could use a smaller one. I'm not sure if or how to derate for the square wave.

Yeap... I noticed that too, but kept quiet 'cause I thought that's the way it was supposed to be... I've changed the values of both to 0.25 and it seems that the output is 124.5 VDC now. No big deal. Just out of curiosity, how could I fine tune the output in a simple way? just by changing the frequency of M1 and M2, for example? Or by applying PWM to both?
What I'll do is I'll buy the transformer that I mentioned and see how it works out. Then I'll trade it for a smaller one and see too if it can take the load.
I think this pretty much wraps up the power supply, thanks.
I'm about to buy the parts for both the supply and the driver. But I'll study the driver some more, make a complete parts list and get back to you before that happens.

Once again, thank you enormously for your help.

 

Question, are the grounds on the left of the transformer (connected to M1 and M2) connected to the ground on the right?
I'm guessing the answer is NO

 

Yes, everything is DC ground.
Will you generate the 60 Hz square wave with the micro? If so leave a small gap, maybe a usec between the opposing pulses so both FETs aren't on at the same time. It's also very important that they both be the same width so there is no DC in the coil.
The FET in the 120 volt line can be the same as the one in the driver. I'll see if I can find some logic level FETs for the 12 volts.
A fuse and a TVS might be a good idea.

 

Yes, everything is DC ground.
Will you generate the 60 Hz square wave with the micro? If so leave a small gap, maybe a usec between the opposing pulses so both FETs aren't on at the same time. It's also very important that they both be the same width so there is no DC in the coil.
The FET in the 120 volt line can be the same as the one in the driver. I'll see if I can find some logic level FETs for the 12 volts.
A fuse and a TVS might be a good idea.

Well, the FET that you chose for the 120V side (M3) is pretty cheap, and it has a low Vgs(th) = 2.0V, that's logic level in my book . But it only has Drain to Source voltage of 100V. Which is no big deal in this power supply, since I'm reading 16V peak on startup and 14V on a normal run.
But the FET's at the left side of the transformer run at a different drain to source voltage (24V tops). Maybe we could use the same FET for M1 and M2?, only thing would probably be to switch them through transistors connected to the MCU, to make sure they're properly driven?
No problem with delay between switching of M1 and M2, I can easily make that happen with a $1.00 dlls 8051

 

I keep screwing you up with the models. The FET I was talking about is the one in text for the driver.FDA33N25 I think.

Good idea if you level shift it with a transistor any old FET will work as long as it's rated for 30 volts or so and can handle the 30 amps at start up.
Yes, the same one for both.
Do you need a schematic for the driver?

 

I keep screwing you up with the models. The FET I was talking about is the one in text for the driver.FDA33N25 I think.

Good idea if you level shift it with a transistor any old FET will work as long as it's rated for 30 volts or so and can handle the 30 amps at start up.
Yes, the same one for both.
Do you need a schematic for the driver?

That would be nice, thanks... I'm willing to bet it's a simple totem-pole pair using a 3904 and 3906, for example? No need to sim them for me, just link me to a graph or something and I can take it from there.
EDIT, yes you're using FDA33N25 for the high voltage side of the driver, that's $2.66 dlls, not too shabby...

 

That would be nice, thanks... I'm willing to bet it's a simple totem-pole pair using a 3904 and 3906, for example? No need to sim them for me, just link me to a graph or something and I can take it from there.
EDIT, yes you're using FDA33N25 for the high voltage side of the driver, that's $2.66 dlls, not too shabby...

Is your micro 5 volts?

 

Is your micro 5 volts?

Yes, with configurable I/O as inputs, quasi-bi, open-collector and push-pull outputs.

 

OK. Cool. We'' use a little FET then.
Don't worry about the turn on delay. It came for free with the level shifter.

 

OK. Cool. We'' use a little FET then.
Don't worry about the turn on delay. It came for free with the level shifter.

Thanks, but I can't find the TR40E06N1 mosfet anywhere! not even Google!