Hi,
Yes, certainly you can estimate the current rating of a transformer winding if you measure the wire diameter, which you say is 2.7mm = 0.1063" which is AWG #10 Heavy Film magnet wire. The area is 10,400 circular mils, and for a large transformer (although you never said how large, large is), is likely designed at between 500 Circular Mils/Amp (C.M./A) to 600 C.M./A, making the current rating likely between roughly 17 Amps to 21 amps. Now, having said that, the actual current rating will depend heavily on the total DC resistance of that winding, which I do not know. If you can, please measure it, not with an ohmmeter, but with a good DVM or two. Procedure for measuring low-resistances with a DVM. Using a lab power supply, or a D-cell battery and a 1-Ohm, 5 watt resistor, if no lab power supply is available, connect the source positive (lab supply or D-cell) in series with the 1-ohm resistor, then connect the other side of the 1-Ohm resistor to one-side of the winding to be measured, and connect the other side of the winding to be measured back to the source (lab supply or battery) minus side. Connect DVM-1, set to the 2 VDC scale, across the 1-Ohm resistor and connect DVM-2, set to 200 mVDC Scale (or lower if it has a lower scale), across the terminals or wire ends of the winding to be measured. If you only have 1 DVM, that will do, but you'll need to work quickly by having it initially setup for DVM-1 above, take a reading as quickly as possible if using a battery (since it will almost immediately start to go down in voltage), then as quickly as possible, connect it as DVM-2 above and take that reading (don't forget to change the voltage scale unless you have an autoscale DVM). If you are using a lab supply, there is no need to hurry up. Compute the unknown winding resistance as follows: Take the DVM-2 voltage divided by the DVM-1 voltage and this equals the unknown winding resistance. Once you have the winding resistance, you can compute the power dissipated in that winding by Power=I^2*R, with I=Current in the winding, and R=the measured/computed resistance of the winding. From there, it really depends on how big the transformer is. In order to set a maximum output current spec for that winding, knowing the transformer size and the lamination (core) dimensions, I could make a calculated guess at how much power loss that winding could safely tolerate, then calculate the current (I) from the formula above: I = Sqrt(Power/Resistance). Since I don't know how large, large is but you do, I can't make an estimate that way. Even if I did know or had a picture, I would still need the winding resistance measurement. You may ask why you can't simply measure the winding resistance using your DVM. The answer is that it is an low-Ohm measurement and your DVM leads may very well have more resistance than the winding you are trying to measure. Therefore, you need a more accurate method. This method works well for most DVMs down to a few milliOhms with a 3.5 digit DVM and down to less than a milliOhm for a 4.5 digit or greater DVM. Good luck and if you get that data and would like me to tryh and estimate the winding current rating a bit more accurately than I did at first, please send me a private email so that I'll know you're ready. I don't always get to AAC very often as I'm usually very busy at work.
Regards,
Kamran Kazem

What a paragraph is:

A paragraph is a group of words put together to form a group that is usually longer than a sentence. Paragraphs are often made up of many sentences, typically between four long sentences or 10 shorter ones.

Sometimes however, you might get a paragraph with only one or two long sentences. Paragraphs can begin with an indentation (about five spaces), or by missing a line out, and then starting again. This makes it easier to tell where one paragraph ends and another begins.

Now I am sure why I did not read your post.

 

A paragraph is a group of words put together to form a group that is usually longer than a sentence. Paragraphs are often made up of many sentences, typically between four long sentences or 10 shorter ones.

Sometimes however, you might get a paragraph with only one or two long sentences. Paragraphs can begin with an indentation (about five spaces), or by missing a line out, and then starting again. This makes it easier to tell where one paragraph ends and another begins.

Umm!
don't mind me for being stupid but what does paragraph had to do with my PSU

 

Still trying to get better load regulation.
Last attempt I got 11mV difference at max load.

Changed the resistance to 1% ones.., better wattage margins. Thicker wirings.
Tantalum caps where necessary.
Better connections.
Over all Voltage is variable up to 37V but at lighter loads. Load regulation is same.
Heavy load max voltage will be at 30V max.

I can't seem to stabilize the LM723 Vcc. Making a regulator for this.
I think this is the where my regulation problem lies.
What do you think guys?

 

Well!. Every attempt to get the regulation down from my best limit at 2.2% failed.
Nothing seemed to work.

Finally. The trick hit me.
Only a slight changed was needed.
I got what I was aiming for. Now my load regulation is 0.03%.
At 30V with a 12A load, regulation change is no more than 0.03%.
All the components are safe to touch at max load

Thanks L Chung. You inspired me.
And I never gave up.

Now comes the current adjustment.
Best news is I got the Texas Int. new Current Shunt monitors.
It will be great addition.

 

Maybe it is difficult to read a long paragraph?

 

Maybe it is difficult to read a long paragraph?

Sorry ?

 

I was remarking on the post from "atferrari" about paragraphs.

 

I think I have mastered linear regulation
Completed the wiring of the Voltage regulator end checked with a more sensitive multimeter.
Voltage change at max load is in the range of third decimal place and change I can get is 0.001V, or so I think.
So how can I check for a perfect specification.

 

So how can I check for a perfect specification.

You'll need a 4-1/2 or 5-1/2 digit DVM and a oscilloscope in order to test your power supply.

Failing that, another regulated voltage source(a LM317T will do) between 0~30V can be used along with a 3-1/2 digit common DVM. Place the DC source in series with the DVM and adjust the DC source to Vout-0.5 volts. Set the DVM at 2V or 200mV range to give about 90% full scale reading without output load connected. Only these two ranges will give you good resolution. If you are confident you can use the 200mV range instead and adjust the DC source such that 190mV is showing on the DVM without load.

An electronic load built by a VR and several 2N3055s mounted on heatsink can be used to serve as an adjustable output loading.

If the supply is 0~30V, then you should test it at least at 25% steps of its design output voltage. So test it at 0.5V, 7.5V, 15V, 22.5V and 30V with the maximum loading current the supply must drive. You will need to vary the load to get this current. Connect a scope to the output and select AC coupling and 1mV per division and watch out for any oscillation or ripple at the output. A badly oscillatory output would look perfect on a DVM because of the filter inside the DVM at the DC volt range.

Record the load current, voltage before loading, under load & voltage after load removal.

Post the results in a table.

 

OK.
How can I make that electronic Load you referred to.
Any diagram that I should follow?

 

There are many circuits on the internet for electronic load. Just search Google for "electronic load circuit" and you will get many hits.

One of them, from www.w1ghz.org website, using easily obtainable components and maintains a constant loading, is shown below:

 

That's a very useful one

 

Hey guys.
The load tester is done but I am not getting a resistance change , MOSFET is always on.
Does this circuit work.
All I get is full Voltage at the gate, all the change I see is a 0.5V difference when the POT is zeroed.
Load resistance at 1.5A node to drain is 1.6Ω always, when I ground the gate it increases to 60Ω.

From what I can see the opamp is not decreasing the gate drive, Voltage measurement shows 0V to 1.1V at NI input so which means if the output is at full Voltage the Inverting pin ...........( I just thought of something )

Oh jeeeeez...I think I should connect a supply at the drain for the circuit to work properly...BRB.

 

Oh jeeeeez...I think I should connect a supply at the drain for the circuit to work properly...BRB.

I hope you truly understand what BRB means.

It means "be right back". It has been 4 days now.

So what happened?

 

Darn it... Sorry about that,
Something came up when I was just about to do what I was going to do.
And now you have mentioned it, I can't seem to remember
I was going to do something, I know I have made a silly mistake, but as I said I got work to do and the load circuit is on hold.
I have to revisit the past.
I'll post back. Soon I think

 

Rifaa
Hahahahahahahahaahahahahahahahahahahahahahah

 

Hohohohonohohohohohohohohohoho

 

what's so funny....umer

 

Rifaa is a person who has many fires to put out.

I see your C.R.S. syndrome is starting to kick in.

"Can't Remember" ... ahhh... ...ummm.... "Stuff!" Yeah, that's it...

 

Rifaa is a person who has many fires to put out.

I see your C.R.S. syndrome is starting to kick in.

"Can't Remember" ... ahhh... ...ummm.... "Stuff!" Yeah, that's it...

ha ha ha ha h hoo hoh hoh !!
Oh god... u nearly killed me..

Ahem!!. not bad Sgt. you does have a good picture of me in mind