thanks Norfindel

Umer_Farooq, do you speak spanish? I'm from Argentina, i can help you with the languaje a little.

i dont understand spanish for speak and write

English: CV/CC power supplies are like any fixed voltage power supply, but if output current exceeds the set value, the voltage output lowers to keep output current at that maximum value. Ie, they're constant voltage supplies, but won't deliver more than the set current. To avoid current raising more than it should, the output voltage must get lower. Ohm's law is keeped at all times. That means that if you configure the supply at 10v 1A, and put a 20ohm resistor as load, the output is going to be 10v 0.5A, but if you put a 5ohm resistor, with a normal fixed voltage supply, the output will be 10v 2A, but with the CV/CC supply limited at 1A, the output is going to be 1A 5v (1A*5ohm=5v).

i understand this explaination good explanation

 

when R vaies I varies depend on I = V/R
V is constant and R varies whose I varies
am i right

I varies as a result of load resistance variation..
Ok you got that part.

So in the first example the PSU can be said it has a variable current. Which is not controllable or adjustable.
Second type of PSU is the Voltage variable or a better term is "adjustable" Voltage supply. This Type can handle any voltage which the supply is made for.
Eg: is a 0-30V 5A. Means the voltage is adjustable any range from 0 to 30V but the current is fixed means the current will vary as same as the first explanation. Means this PSU current can also vary 0 to 5Amps depending on the load.

Either way the above two types are CV supplies.
Understood?

 

Amperage is TAKEN not GIVEN.

Voltage is GIVEN.

So If you have a 5v supply with adjustable current and you connect a 56 ohm resistor and a red led to it,
And set the amperage on 1amp, the led will only take 20milliAmps not the 1amp you set the power supply to.
That setting is only a number to 'trip' at. So if you have a setup that draws 1.4amp and you have your supply set to 1A, it will cut power and give you an OVERCURRENT error.

If you crank the knob for the current up to 5 amps, the led will still only be taking 20milliAmps.

So I think what you want, is a 0-30V supply that is capable of supplying up to 5a.

A 5a supply DOES NOT mean it puts out 5 amps to everything. It means 5 amps can be TAKEN from it. If you have a 1,000,000,000A 5v supply, and the same 56ohm resistor and red led, You would think the led would explode. It wont. It will only TAKE what it needs (with the resistor)

so if you measured the amperage coming from your 1,000,000,000AMP 5v power supply while lighting the red LED with the 56ohm resistor, you would only measure .02A.

I think this is where you are going wrong.

So if you had the same setup, but cranked the voltage from 5v to 30v, you would blow up the LED.

Why? because Mr.Ohm said so.

 

retched. U can PM the admin to change ur ID to Mr.Ohm

 

retched. U can PM the admin to change ur ID to Mr.Ohm

I dont think I would be able to handle all the requests for autographs.

 

Are there any applications for a current regulated power supply?
I can only think about current limiting.

 

Are there any applications for a current regulated power supply?
I can only think about current limiting.

Agreed. I think the OP thought you had to FEED a circuit AMPS. So if he had a 5a power supply and had a 1 amp circuit, he thinks he has to 'dial down' the amps.

 

thanks a lot to all friends
R!f@@
retched
Audioguru


Next describe CC Supply


i design a power supply 0-30 Varibale voltage
and 0-5A variable current supply
0-5A circuit use for current limiter

if i design a PSU using Switch method (without transformer) this method better or using transformer method better

thanks a lot

 

A switching supply without transformer will be dangerous to build and test. I don't recommend it. You can use an input transformer to lower the voltage, that would be safer. Will weight more, but will be safer.

It will be more difficult to build a switching supply than a linear supply, and have more ripple, also.

You cannot go more simple than using two lm338k, really.

National recommends this IC on the lm338 page, if you want to go the switching way: http://www.national.com/pf/LM/LM2679.html#Overview

 

Dear Umer Farooq
Good Day!
without knowledge electronics nothing to do
if you have some knowledge for electronics i will happy to help you jest tell me your requerment how meny amp and volts you want to regulate?

 

smnaz.. He says it about two hundred times in this thread.

i design a power supply 0-30 Varibale voltage
and 0-5A variable current supply
0-5A circuit use for current limiter

 

Dear Umer Farooq
Good Day!
without knowledge electronics nothing to do
if you have some knowledge for electronics i will happy to help you jest tell me your requerment how meny amp and volts you want to regulate?

Read the whole thread and OP's previous yhreads.
You are going to have a field day helping him

Umer. Do you understand CC now that others have explained it

 

Umer, Have you seen the type of power supply with the same rating for sale? Do you have a store or website you can link to to show us what you want?

It would help alot if we could see EXACTLY what you are talking about.

 

Umer. Do you understand CC now that others have explained it

hello Rifoo where explain CC term. In CC current not vary with load but this is how possible


please both types of Power supply explain
first i use with transformer power supply with regulator use
Lm317 but the problem is that this IC is max current 1.5A

Second 7805 7812 fix regulator use

third UA723 Ic That problem is 6 or 7-35V but i want 0-30V

Fourth i make using lm338 use but the problem is that max 1A lower than 8V while i design 0-5A current limiter use at 0-30V supply

fifth any idea other regulator whose cover 0-30V and 5A regulator

for regulating the regulator ic better or using transistor and comparator IC use better

i seen that many companies (eg HP power supply) using transistor regulator

 

Please answer the question in post #73.

 

Ok Umer... If you follow my lead I will help you to make one 0 to 30V @ Max 5A adjustable.
Promise me you will do what I tell you and would not change your mind. You have to do every little thing I ask you to do. Those Things are the stuff I learned during my time in AAC. So it will be like all the good members suggestion in making a supply. And every one will be seeing how you progress. and if you stop in between every one will know. OK

 

Do you really need 0 to 30v and up to 5A? Because the problem with linear regulators in wide-range variable voltage supplies (and to make things worse, high-current) is the power dissipation.

Take for example the case where you need 1v at 5A (and that's still not the worst case, as you want it to go all the way to 0v). If the input voltage of the regulator is 35v, the power dissipation on it will be something like (35v - 1v) * 5A = 170 watts. I don't know if there is some kind of linear regulator IC that can get rid of all that heat so fast, but even if it does exist, we are talking about a big, expensive device bolted to a big, heavy, expensive heatsink, and you're going to need a big, heavy, expensive 10A transformer, and some kind of in-rush current limiting.

I'm currently looking at building a 1.25 to 30v 2.5A supply, and i decided to use a switching, variable voltage pre-regulator to keep the linear regulator input voltage at a reasonable level, and thus, keep power dissipation in check. The only problem is that i never built a switching regulator, don't know what to do about the inductor, etc, so this isn't going to be easy (any tips are welcomed, by the way ).

 

Thanks to all
retched
R!f@@
Norfindel

Please answer the question in post #73.

Umer, Have you seen the type of power supply with the same rating for sale?

yes psu with the same rating meet in market for sale but i personally design for learn electronics and for experience

Do you have a store or website you can link to to show us what you want?

No

 

umer u did not answer me .
post 76

 

Ok Umer... If you follow my lead I will help you to make one 0 to 30V @ Max 5A adjustable.
Promise me you will do what I tell you and would not change your mind. You have to do every little thing I ask you to do. Those Things are the stuff I learned during my time in AAC. So it will be like all the good members suggestion in making a supply. And every one will be seeing how you progress. and if you stop in between every one will know. OK

i struggle that you tell me and would not change