Hehe !!! sorry Sgt. my Bad.
Actually I wanted to find the secondary rating and when I did, new idea came, to make a PSU. so it branched to that...and during this phase problem was that I cannot go beyond 30V and I asked why the heck it does not go and every one keeps asking me everything except the exact problem and another problem was that we were talking about the main series pass element capability and all and all and I said I have a PSU that worked with a single power transistor for a long time based on the same circuit and it had had given rock solid performance at current up to 8 amps and so L Chung wanted to check it's performance because his theory was that to use up to 9 of those transistors to prevent them from over heating and I was using just one at 0V to 20V at 8 amp cont. for years, in fact the supply is so old that even the meters are hanging inside it and so be that as it may....and umm..I think L Chung was suspicious of it's load regulation capability and he asked me why I was taking so long to check my power supply load regulation, so I showed him the "why" with pictures that's all. and I guess tht's why this thread seems like .i donno..confusin
I am here to build stuff and to have fun while doing it. It's OK any body hijacks my thread. no biggie. as long as it doesn't interfere with the way he forum works, I'm cool

Oh and by the way, I scraped the insulation to check the wire gauges. it's cool

 

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

Actually quite good, with only 30mV drop.

It is only fair if I also show you mine, measuring the output voltage with/without a 15A load.

 

Actually quite good, with only 30mV drop.

It is only fair if I also show you mine, measuring the output voltage with/without a 15A load.

NO WAY .
You got to teach me that.

 

NO WAY .
You got to teach me that.

Now you know where the 1388 comes from.

Actually, the power supply drops 3mV when loaded. Not bad consider it is also using a uA723 as the regulating IC.

 

Now you know where the 1388 comes from.

.

HUH !!!

 

So what do you use.....
tell me......tell me......tell me......tell me......tell me......
pretty pleeeeeeeeeese

 

Bugger!!!!! jeeeeeeeeeezz I'm so stupid

1388 now I get it
cool!!
Seriously? since when?

 

So what do you use.....
tell me......tell me......tell me......tell me......tell me......
pretty pleeeeeeeeeese

uA723 + nine 2N3055.

 

You just slapped me right on the face with that .....
Seriously 9 of 'em.. can I see the schema..if you don't mind

 

IC you have parallel transformers with bridges.. right?

 

You just slapped me right on the face with that .....
Seriously 9 of 'em.. can I see the schema..if you don't mind

There is no secret component. It is a standard uA723 circuit. The reason I'm not posing the schematic is because there are other bits like crowbar protection, low voltage shutdown, high voltage shutdown, voltage in range LED indication, automatic cooling fan control etc...making the schematic very messy.

Without the above auxiliary circuits, it is just a standard ua723 driving one 2N3055 which in turn drives 8 x 2N3055.

As I said before, the secret is in how one actually wiring up the circuit, and not in the circuit design itself.

 

I know all that stuff. so my circuit will also suffice. OK then.
Let me build it after checking what sgt suggested.
How can I implement ur theory to raise the output.

 

Here's a comparison of what you'll need with an LM317 vs a discrete solution.

The LM317 has automatic current limiting, which the discrete solution lacks.

Some components needed to be added to the LM317 solution to make it more stable, and to provide for short protection (the diodes).

I also added a rough model for the transformer and filter. The diodes have less capacity than your bridge, and I kept the filter cap smaller so that it would take less time to complete the simulation. However, you'll notice that it does take awhile to charge up that 10,000uF cap - even when the peak rectifier current is around 40A.

 

Just learned a new trick to increase the output and it worked.
PSU is getting ready

 

OK, so why don't you post what you did?

Did you try what I suggested, and/or what Elbc1388 did? and did it help?

 

I am making the circuit after some shut eye. After the voltage regulator is set and load tested I will post with the specs in a new thread or in a blog. what ever would you recommend, thread or a blog.
I am doing the heat sink work, I changed to TO-3 packages and need some drilling to do
The method sgt did not work in practice, it seems that the IC does not change it's output with any variation in it's supply as long as it's supply in with in specs.
A higher supply will blow it, too low is not enuf, and the zener I provided as t 2W. and is sufficient for the IC.
As for L chung's advice it's a must that I need to have proper gauge wiring for higher current PSU, and as for the out puts I am putting three 250W 16A TO-3 packages, and are premium components. so power and current sharing will be with in limits.
Heat is not a problem to me, since I have made automatic fan cooling for my amps, it's child's play to on and off them at any temp I want.
Time is taking to make the metal work.
My cnc is on hold till this is up, since I have to get new brushes for the motor that I intend to use for the spindle and also to speed test it I can use the higher voltage.
Previous supply I was planning to make halted because of the same reason, I cannot get above 30V. now that I figured it out it will also be done but after this only, that supply will go up to 80VDC, but after I master the safety limits by experimenting on this.
I will be blowing up a lot of things, may be the outputs as well. This will always happen, if not it's not a successful project.
What can I say, I am dangerous engineer.

 

This is the basic schema I just cooked up, values are not written as I will be testing with different values to blow em .
CC is not yet implemented. will be done later.
The voltage level that I needed is reached by changing the resistor values

diagram removed . Changes are being made.

 

Put the fuse on the mains side of the power switch.

Remove the cap from across the power switch. The only thing it's doing is creating a safety hazard, as a part of the AC will be coupled through it; and if it shorts out, mains power will be applied unless the fuse blows or the unit is unplugged.

 

Put the fuse on the mains side of the power switch.

Remove the cap from across the power switch. The only thing it's doing is creating a safety hazard, as a part of the AC will be coupled through it; and if it shorts out, mains power will be applied unless the fuse blows or the unit is unplugged.

Is it ?

Come to think of it, I have seen caps across switches, in lot's of em. I believe it will suppress the spark between switch contacts at power off.
What do you think?

As for the fuse I will change and upload once the values are finalized.
Thanks for the heads up

 

OK Guys here's the latest verdict.
I had built the voltage regulator and I can get up to 40V if I want...no problem on that now. Before that I am going to wire the thing properly. Please find the attached picture.
I am using 10 AWG to wire the main bus.
I have done a load test to see how well the transformer handles current.
The filter caps are stud mount and is 30,000μF. Bridge is a 35A one as you can see.
Here are the measurements that I took.

Transformer no load voltage is 32VAC
Transformer terminal voltage with a 14.2 Amps load is 30VAC.

No load voltage at the filter output is 43.19VDC
Loaded to 3.65 Amps voltage drops to 39.71VDC.
I presume 14.2 Amps load will drop it to 35VDC approximately.

The wires as I said are 10 AWG marine grade cables and all the joints are stud mounted or soldered.

Where do you think the main loss is?
Is it the caps or still the wires.

Bear in mind this is with RAW DC. As L Chung suggested, I am giving attention to minute details.

Is this results OK for such a load and can I continue to mount the regulator?