Hi, first of all sorry for bad english.

I have a 110Vac transformer and need a 110Vcc output i have done this


shunt transistors are 2SA1941 (not in proteus)

my questions are:

-do i need 4 PNP or 2 should work?
-how can i calculate R1 R2 R3?
-Is C1 big enough?
-Should i put a series resistor between Vo (from regulator) and R4?

thank you soo much!

 

Your output voltage is set by R4, R5, which is too large. Make R5 7K1, to give you 110V, R3 depends on how much current your output needs, i would make it 27 ohms, R1,R2 can be determined by the maximum output current. C1 is ok, no resistor needed at the output.

 

Ohh i am so sorry i forget the most important detail LOL.
im making this for a 110 VAC 1000W so i need about 10A

 

What you have there is going to be DC not AC and nowhere near 10 amps 110 more like 22 mA

 

before the rectifier. I need 110 VDC from(this is what i trying to do) 110 VAC (this is what i have)

also need 10A in the DC output

 

Where is your transformer?

Is your input voltage AC or DC? What voltage is it? How much current can the input supply?

Do you want AC or DC on output? What voltage is it? How much current?

 

I have a 220VAC/110 VAC transformer 1000W (10A) i cant touch or modify that.

i want a 110 VCC output with 10A

 

Thank you. I was not sure of what you were saying. I am easily confused. Dipolar-ism. An electrical disease.

 

How well regulated does it need to be?
The easiest way would be to use a Variac to control the mains input to the transformer and a rectifier with filter cap on the output.
To make a 110C DC 10Amp power supply is not trivial. Your circuit is not at all suitable, as be80be points out, you have shown a low power supply.
R1, R2 and R3 will need to be changed at least.
I think having a lot more pass transistors is a good idea. This power supply needs to survive a short on the output so look at fig 15 for some ideas.
http://www.ti.com/lit/ds/symlink/tl783.pdf
Just realize, 110VAC rectified will give you 110 x 1.414 = 150VDC and that is over the reg voltage limit.
Also, your 110VAC will go higher depending on the mains fluctuations.

I think you need to look at other circuits.

 

thanks dendad. I can use anything what i want to do this. i started with that but i can change to anything. i need about 90% i guess. R1, R2 and R3 are the standard for proteus i know they are wrong but i asked in first post.

the transistors in fig 15 from datasheet has a 6A Ic current. Do you think i should change that to proper transistors and work on that better?

thanks and sorry again for my english

 

Ok im doing in that way look:



What do you think about using only one power transistor? THIS--> https://cdn.macom.com/datasheets/2N6676_2N6678.pdf

And what can i use in PNP transistors? because they dont do power justo switching right?

thanks a lot

 

You will need multiple pass transistors if you go with this circuit, but I expect smoke and hot metal bits flying around
Work out the dissipation of the transistors when the output is shorted, and that will happen.
What is the load you are trying to drive? Is it constant or varying?
For instance, when you first turn this on, the capacitors on the output will have 0V, and so the full 150VDC will be across the supply. And the current pulse to charge up will be high. Can it survive that?
When running at 10Amps out, the pass transistors will have to dissipate (150-110)V x 10Amps = 400Watts.
A good heatsink and fans will be needed.

A switch mode supply may be better for you to use, but design of that too is non trivial at this power level.
I doubt I would attempt to design one myself.
There may be others on this forum that can help.
But more info is needed, like what your real load is. That can have real design influences.

 

Variable load. i can give more info tomorrow

 

Ok mi back, i already have my rectified output (just the transformer and a big cap and some power resist.) i have 150Vcc.

the load is resistive some industrial devices for testing(i guess the 90% of time it will work at 6Amps max) what do you think about BUV21for the NPN ?

what about "stepping down" the 150 Vcc until 110Vcc before the regulator or even before the rectifier? Varicap maybe so i can have 110Vcc in the rectifier output(110 /sqrt(2)?

sorry for all this and thanks!

 

I have a 220VAC/110 VAC transformer 1000W (10A)

You have to derate the transformer about 60% for a rectifier-capacitor output due to the high RMS peak currents such a circuit draws.
Thus the maximum DC output should be no more than 6Adc for a 10Arms transformer.
10A can likely be drawn for short periods of time (no more than a minute or so).
Otherwise you can overheat the transformer.

 

what about "stepping down" the 150 Vcc until 110Vcc before the regulator or even before the rectifier? Varicap maybe so i can have 110Vcc in the rectifier output(110 /sqrt(2)?

That would be good but you can't do it with a varicap capacitor, you need a transformer.

One way is to add a 10A 110Vac to 24Vac transformer on the main transformer output, and connect the secondary in reverse phase with the main transformer output to the rectifier-capacitor so it subtracts the 24Vac from the 110Vac (below).
That will reduce the AC voltage to about 86V and the rectified DC output to about 120Vdc.

It you used a 15A, 110Vac to 24Vac transformer then you could increase the DC output current to about 9A, since the 24V transformer secondary output current through L3 generates a primary current in L2 that subtracts from the L4 main output current.

 

If the supply must withstand short-circuiting (and it is foolish to design assuming it won't get shorted for the type of application described) or significant overload, you will either need to implement fast fold-back current limiting or use multiple output transistors. You might find a transistor with sufficient DC safe operating area to get by with 10 of them at 6 A with 120 V input, If you use reasonably fast fold-back limiting you might be able to use as few as 4 transistors. I haven't spent a lot of time looking, but once you get up to 100 V, DC safe operating area for many transistors is well under one ampere. For example, the 2SC5200 has a DC safe operating area allowing 400 mA at 100 V (40 watts), but is rated at 250 V and 17 A, 150 W. This is due to "second breakdown."

A BUV21 safe operating area would allow about 300 mA at 120 V - you would need 20 of them in parallel to make a supply that would withstand short-circuiting at 6 amperes for more than a few tens of milliseconds.

You might be able to use SCRs in the rectifier and turn them off fast enough to protect the output transistors against short-circuiting, but you still have to consider the charge on the filter capacitors and the fact that the SCRs don't turn off instantly.

A power supply like this is far from easy to design. I have done a lot of power supply design. I would consider this sort of supply a job requiring a lot of attention to detail and careful analysis. Building it moderately complex. Dendad's statement about "expect[ing] smoke and hot metal bits flying around" is not an exaggeration.

 

Ok first for all i wanted to say variac no varicap. my bad.

and second i can now change this and do it for 5A instead of 10A what do u think about this?

is from the tl783 datasheet. what do you think PNP should be?

thanks

 

Did you notice the comment from EDP above?
If the circuit you have shown is current limited at 5Amps, and has a 125V supply, then a short on it will have the pass transistor trying to dissipate 125 X 5 = 625Watts.
As I mentioned before, smoke and hot metal!

 

Im back with this project, i've been working in a smps this is what i have

PWM and sensor:



power:



i left this here in case anyone can say anything, meanwhile i will make the boards and burn stuff..

thanks a lot

(im sorry if i should made a new thread )