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need to get a 1.5VDC /25amps power supply for my superconductor experiments.

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vimalkhanna

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I have 5.0vdc supply which lowers down to 3.5VDC .However , to stabilize ,I need a voltage ref. of 1.25VDC .
Maybe a 3pin regulators with LDO capability for high currents and minimum power dissipation.
Can our members suggest ideas and reference sources ...
 

The TL431 is a programmable precision reference. 3 pins. Inexpensive.

Also known as adjustable zener.

Looking at the datasheet...

It doesn't go down to 1.25V. You'll either have to install a resistor divider. Or locate a cousin of the 431 that goes down to 1.25v.
 
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I tried experimenting with MAX6161 for the 1.25VDC ref. source and the 5VDC linear comparator MAX9100 to give me a stable output feedback stabilization.
However , I do not know what to use for linear regulation of the 1.25VDC output to 20Amps ratings .
Honourable experts ,,kindly help if you have ideas to proceed....
 

I am going for linear regulator but the comparator input and ref. sources of 1.2VDC ///low comparator input supply /output are the main bottlenecks
 

I think it will work!(sorry there is no engineering software on this PC)
IMG_1198.JPG
Test it on pspice and see what will happen!
 

Hi All.
When you say 25amps no way any linear regulator helps you. Go for any SMPS whith synchronos rectification, That will be best suits you

Thanks
Grittin
 

I agree with previous post. You can readjust the SMPS to 5v and use a sync.(mosfet half bridge) buck circuit.
There are many controllers for this circuit even with internal 30A switch.
 

For this big current no Linear regulator will help and at the same time for critical regulation. You can design an SMPS with 5 volts in and 1.25 volts out with 30 amperes current capability. Still if you want to experiment with linear you can use LM317 as reference (1.2 volts minimum). Still suggest for SMPS for a best solution.
 

Tried SMPS with rect but the voltage is unsteady.and load regulation drops are high .
Suggested using an optocoupler for closing feedback loop ,but none available at low voltage DC control..of 0.9VDC...
request help...
 

Consider using a single large 2 V lead-acid battery. (Or it might be 2.1V.)

I have heard that such batteries are used in forklifts, telephone switching depots, and submarines. They can't let them go bad before replacing them. So if you check around you may find a used deal somewhere. It will be large and heavy.

Add a power diode to drop 0.6 or 0.7 V. Dissipate 20W when 25 amps goes through it.

A dropping resistor will not maintain regulation. However if you think it will work then it should be about 0.02 ohm in order to drop .6V. It will dissipate 20W.
 
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I understand this and tried to see for the VRLA batteries in telecom exchanges&Forklifts. I talked to Exide /Goodyear/Amptek--manufacturers . The size 2VDC/500AH is 750mmHx 325mmWx 250mmB..which is roughly 20 times the volume of my 40watt SMPS.Can I use such a product for ref to my unit with 200 Lx125 B x 55mmH ??
I have contacted the Ni-cd and Ni-mH suppliers toofor such a ref source...Probably a single button cell used in wristwatch/calculator /remote toys could be an answer..
 

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