I will be using higher guage wires and believe me I have plenty of power transistors, you'll be surprised to see my stock.

My rectifier is rated at 35A 400VDC, with a filter of 30000μF.

If you like add more filters I can do it. Just throw in a figure.

None of you still suggested how to increase the output.
Puleeeeeeeeeese

 

The problem is not the rectifier. But the filter cap, and how it is charged. I have some interesting papers on it. But not on the computer I am sitting on now.

 

The problem is not the rectifier. But the filter cap, and how it is charged. I have some interesting papers on it. But not on the computer I am sitting on now.

That's something new... you GOT TO TELL ME..
I'm not leaving this chair before you give it to me...
Puleeeeeeeeeeeeeese...pretty pleeeeeeeeeese

 

Hello,

Did you read the article of Tony van Roon?

http://www.sentex.ca/~mec1995/circ/ps3010/ps3010a.html
http://www.sentex.ca/~mec1995/circ/ps3010/ps3010b.html
http://www.sentex.ca/~mec1995/circ/ps3010/ps3010c.html
http://www.sentex.ca/~mec1995/circ/ps3010/ps3010d.html

Perhaps you will get some ideas from it.

Greetings,
Bertus

 

I used google and this one is quite good http://www.audiofaidate.org/it/materiale/20_020_020_001_PowerTransformer_FilterRatings.pdf

 

I guess I have enough on the filter side then. 30,000μF for 12 Amps should be enough.

Bertus
They also have 30VDC max, and it uses 15A 150W transistors. I have 25A @250W, a couple of these can take 12 amps like child's play, don't you think.
That supply cannot compare to the power I have right now.

I know how to built these, but I never tried to go above 30V before. This is the first time I am trying. Now I have two PSU s. One can go from 0 to 20 at 8A. second is a fixed 13.2VDC at 10A. Both have single pass transistor and I have been using them for a long time. Even low volt high current states, the variable one is rock solid, built on the same circuit I have posted (it uses a 2N3771 as the series element), but this have fold back current limiting, I cannot adjust the current.

So I need a little help on how to increase the output.

 

Hello,

Tony uses several transistors to spread the heat dissipated.
Imagine inout 40 Volts, output shorted, max current 12 A.
Then you will have to dissipate 40 X 12 = 480 Watts.

Greetings,
Bertus

 

One can go from 0 to 20 at 8A. second is a fixed 13.2VDC at 10A. Both have single pass transistor and I have been using them for a long time. Even low volt high current states, the variable one is rock solid, built on the same circuit I have posted.

How solid can it be? Can you do a test and show us how it performs?

Please connect a DVM to the output without load and then place a 8A load across the output.

What is the voltage reading on the DVM changes before/after the load application?

 

What am I missing here guys?
It's not the power I am concerned . It is the Voltage
I cannot go beyond 30V, why is that?

 

How solid can it be? Can you do a test and show us how it performs?

Please connect a DVM to the output without load and then place a 8A load across the output.

What is the voltage reading on the DVM changes before/after the load application?

You won't proof....OK then. hold on to ur pants, cause Kansas is going bye bye

Oh god!!! time to find that nichrome wires........

 

You won't proof....OK then. hold on to ur pants, cause Kansas is going bye bye
Oh god!!! time to find that nichrome wires........

Any (big) resistor will do. You don't need to do the test longer than a few seconds. Just long enough for the DVM reading to become stable for you to read the output voltage.

What am I missing here guys?
It's not the power I am concerned . It is the Voltage
I cannot go beyond 30V, why is that?

Many power supplies uses auxiliary control supply riding on the positive supply rail and thus can drive the pass transistor(s) to near saturation to have a higher output voltage from the transformer+rectifier setup.

 

Many power supplies uses auxiliary control supply riding on the positive supply rail and thus can drive the pass transistor(s) to near saturation to have a higher output voltage from the transformer+rectifier setup.

Hey this former have one more high voltage output, How can I do that.

 

Hey this former have one more high voltage output, How can I do that.

You don't need a high voltage winding.

A separate 12V-0-12V, 1A auxiliary winding will do nicely. Many big power transformer has these auxiliary voltage windings saving the user a lot of troubles.

Without such user can always use another small transformer as the control transformer.

PS. Why does the load regulation voltage test takes so long? It could be done within half a minute.

 

One of the first problems I see with your schematic is R1/D1.

Since D1 is a 1N5938 36v(nominal) Zener with it's rated voltage at 10.4mA, and R1 is 680 Ohms, you already have a problem.
42v-36v = 6v, 6v/680 Ohms = 8.82mA. How much current did you need to drive the LM723? There is not any current left over for the LM723. Oops.

What you really need there is a pass transistor, so that you don't wind up with lots of power dissipation in the Zener and resistor, and so you get better regulated voltage to the 723.

I threw together a simulation using LTSpice. I don't have any Darlington transistors in my library yet, so I used a couple of discrete transistors.

R1 replaces your R1; it's 430 Ohms. You'll then get the 10mA through the Zeners.
R2 limits the maximum current through the Darlington configured transistors to 1A. This is too much current for the transistors I used, but the excessive current only occurs when C1 is first charging. Replacing Q1 with a 2n3055 and Q2 with a 2N2222 (or simply a power Darlington) would allow for much more current; so R2 could be decreased in size to perhaps 10 Ohms.
I didn't have a 1N5938 Zener in my library either, so I just used three 1N759 12v Zeners in series as a substitute. Since there are two base-emitter junctions added by the Darlington resulting in an additional 1.4v drop, two 1N4148 small signal diodes were added to the Zener string to compensate.

Rload represents the LM723 when it is drawing 150mA current. 36v/240 Ohms = 150mA.

 

Another alternative to get "rock solid" 36V for the LM723 is to use the high voltage three terminal regulator like the LM317HV.

 

PS. Why does the load regulation voltage test takes so long? It could be done within half a minute.

this is why.... when I talk of PSU, I get blessed with PSU's

Just arrived from Island Aviation another item to my junk yard
further more I got these print heads

do you think they are useful for anything other than printing?

I'm getting on it, give me a sec. had check em first

 

Hey guess what, I got another LCD to play with

Cool HUH!!!

 

One of the first problems I see with your schematic is R1/D1.

Since D1 is a 1N5938 36v(nominal) Zener with it's rated voltage at 10.4mA, and R1 is 680 Ohms, you already have a problem.
42v-36v = 6v, 6v/680 Ohms = 8.82mA. How much current did you need to drive the LM723? There is not any current left over for the LM723. Oops.

What you really need there is a pass transistor, so that you don't wind up with lots of power dissipation in the Zener and resistor, and so you get better regulated voltage to the 723.

I threw together a simulation using LTSpice. I don't have any Darlington transistors in my library yet, so I used a couple of discrete transistors.

R1 replaces your R1; it's 430 Ohms. You'll then get the 10mA through the Zeners.
R2 limits the maximum current through the Darlington configured transistors to 1A. This is too much current for the transistors I used, but the excessive current only occurs when C1 is first charging. Replacing Q1 with a 2n3055 and Q2 with a 2N2222 (or simply a power Darlington) would allow for much more current; so R2 could be decreased in size to perhaps 10 Ohms.
I didn't have a 1N5938 Zener in my library either, so I just used three 1N759 12v Zeners in series as a substitute. Since there are two base-emitter junctions added by the Darlington resulting in an additional 1.4v drop, two 1N4148 small signal diodes were added to the Zener string to compensate.

Rload represents the LM723 when it is drawing 150mA current. 36v/240 Ohms = 150mA.

Much appreciated Sgt. I will get on this afterwards and will post the result

 

Rifaa,
Perhaps you don't realize it, but you keep hijacking your own thread by introducing new topics. This can quickly make a mess out of a thread, by being hard to follow.

You started with questions on a transformer, then changed to a power supply design, and then start mentioning completely unrelated components that you received from somewhere. As a result, people have lots more reading to do in order to figure out what you're actually trying to accomplish.

In the beginning, this thread's subject was about determining what kind of power output your transformer has; and now it's evolved into a power supply thread with miscellaneous bits thrown in.

When the course of the thread changes so much, it is really better to start with a new thread that has a more descriptive subject line of the new topic, like:
"LM723 Power Supply Design Q's: 2v-35v @ <=12 Amperes?"
and include a link back to the prior topic on the transformer thread, in case people want background information on your transformer.

By the way, it looks like some of the insulation on your transformer leads are damaged. I suggest that you use some heat shrink tubing over the damaged areas to reduce the possibility of electrical shorts.

 

PS. Why does the load regulation voltage test takes so long? It could be done within half a minute

I loaded my supply with a 20W resistor, supply set at 16V, ammeter shows 8 amps. No load to load voltage is from 16VDC exactly to 15.97VDC.
What say you
PS. The transformer starts to cry when I load to 8A