0-30V Stabilized Power Supply

[audioguru2]

With the 24V transformer, the max output voltage from this project is only about 25VDC.
The 1000VA transformer will only partially be used since at 24V AC only 102VA is needed. It is expensive, big and heavy.

 

[morpheous87]

I want to ask, if the power supply gives 3A at 30V, can it give ~7A at 12V when charging 12V batteries ?

 

[audioguru2]

I want to ask, if the power supply gives 3A at 30V, can it give ~7A at 12V when charging 12V batteries ?

Of course not! Its max output current is only 3A.
The transformer is at its limit when the output current of the project is 3A.
The output transistors and driver transistor (and maybe opamp U2) are also at their limit when the output is 3A.

We have a thread about increasing the output current to 5A. A 3rd output transistor was added and a bigger transformer.

 

[mas1]

hi all;

i maked this psu first version. it is worked very good but damaged. after i think make a new and more profesional. i look your updates and make a new pcb. i complete all but dont complete pcb routing. i want one side pcb. proteus autorouter draving 2 side. i dont want 2 side. i want only 1 side. maaybe need change component placing. can you complete this? i attached all files.. im using proteus 7.7 sp2. thanks. regards..

0-30v_stablized_new_pcb.rar

 

[garik111]

Hi Andreas.
It is too bad that the power supply kit posted in the original project was very poorly designed.
We have made a few modifications over the years to fix it and I have posted the latest parts list and schematic millions of times.
Here they are again:

Hi
Please suggest a heatsink and where I can buy transformer online? thanks

 

[audioguru2]

Since you do not show where you are then we cannot recommend parts.

The max total dissipation from both output transistors is 117W. They should have their chips  below their max temperature of 200 degrees C. If the ambient is 30 degrees C then the total allowed allowed temperature rise is 175 degrees C. 2N3055 transistors have a thermal resistance of 1.5 degrees C per Watt. An insulator with thermal compound is about 0.2 degrees so the total thermal resistance is 1.7 degrees C per Watt. The total thermal resistance must be at least 200 degrees/117W= 1.7 degrees C per Watt so the heatsink must be pretty big and a fan should be used.

I am in Canada so I usually order online from Digikey and Newark. They both have very detailed catalogs online. If I order before 8:00PM then it is delivered to me the next morning.

 

[Supernova]

I Have built the original circuit. It works perfectly, but now i want to modify it so it will give negative voltage. Can somebody help me do this because I don't even know if this is possible.

 

[audioguru2]

1) The original project has opamps rated for an absolute maximum supply of 36V operating at 40V.
2) Its transformer, rectifier diodes, driver transistor, output transistor and many resistors get too hot and will probably fail soon.

It cannot produce 30V at 3A.

So we fixed it to work properly and be reliable.

If you connect its + output to ground then its 0V output is a negative output voltage.

 

[mas1]

i have a question, can i use ILC7660 for negative opamp supply? i think use smps. transformers is very big,heavy,expensive,old vs.. thx..

 

[audioguru2]

i have a question, can i use ILC7660 for negative opamp supply? i think use smps. transformers is very big,heavy,expensive,old vs..

The existing negative -1.3V supply for the opamp U3 is simple, cheap, supplies plenty of current and is fairly well regulated.
The iCL7660 needs to have a resistor feeding a 9.1V zener diode to power it plus two capacitors. Its output current is low and is not regulated. Its output voltage must be reduced to -1.3V somehow but still allow lots of current.

Why are you talking about a smps transformer?

 

[mas1]

this circuit working with old transformers. designed for transformers supply (sine wave) alternative voltage. will not work on dc voltage. because you can not converte positive dc to negative whit passive components for opamp supply.. 

 

[audioguru2]

this circuit working with old transformers.

Maybe.
It uses ONE ordinary 28V or 30V, 50Hz or 60Hz power transformer.

designed for transformers supply (sine wave) alternative voltage. will not work on dc voltage.

Of course not, it uses an AC power transformer, not a 40V battery.

because you can not converte positive dc to negative whit passive components for opamp supply..

Why don't you power this project from a power transformer like everybody else?

 

[mas1]

Look please...

 

[audioguru2]

This project is powered from an AC transformer, not DC.

 

[mas1]

are you shure? what i say bro?

this project powered ac. i want use smps (dc). i say will not work. because there are no sine wave for negative supply.. and i say ILC7660 usable for this.. okay?

red marked area for negative supply..

 

[Hero999]

I don't see why it wouldn't work.

The ILC7660 would need a voltage regulator to reduce the supply voltage to below 10V.

Look at the datasheet of the ILC7660 for its maximum output current rating.

Calculate the negative supply current taken by U3 when the output voltage is 0V.

If it's above the ILC7660's maximum rating it won't work.

You could use the 555 timer and some diodes as an alternative which would work as long as the current through the 555's pin 3 is below 200mA.

 

[ksenhuck]

Please guys, i'm completly lost... its my first time here....

i just want to know, pleeeease ,which page  the final circuit are? the pcb....

i want to do the 0-25V 3A, so i can use an 25v-3A transformer, using the components of 30V-3a right? because i have already bought them, but i bought using the original circuit...

pleease,i need the final pcb circuit and the list of the news components i am  supposed to buy.....

PLease guys, please

Thanks a lot !!

 

[audioguru2]

A little 25V/3A transformer will overheat when it tries to supply more than 75VA.
If the output voltage of the project is 25VDC at a current of 3A then the max (b]load(/b) power is 75VA.
But the rectifier bridge uses an additional power of 6W max and the R7 current-sensing resistor uses 4.2W max. The electronic circuit also uses additional power. Then the transformer must supply more than 85.2VA which is higher than its max allowed rating of only 75VA.

I posted the latest parts list and schematic a few hundred times here and I don't have time to post them again because your transformer is too small and maybe you can't find the modern opamps anyway.

 

[ksenhuck]

i haven't bought the transformer .. i will check out again to find  your schematic here, i just want to buy the right transformer....
tks

 

[ksenhuck]

Please audioguru,  but this is the final circuit right?

http://www.electronics-lab.com/forum/index.php?topic=19066.msg100521#msg100521

tks