# 100 amp DC into 2 circuits

Discussion in 'The Projects Forum' started by pjhart, May 16, 2013.

1. ### pjhart Thread Starter New Member

May 16, 2013
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0
Hi,

I have a 100 amp 13.8 DC power supply, its very clean power as it was used to power a car audio display, short version of this whole question is how do I make the voltage and current adjustable to make a sweet DC power station.

I am interested in making a power supply for projects and was going to use that for my DC supply. I am concerned that switching to AC to get a higher DC voltage selection will add some noise into the AC. My best lead so far is this http://www.rose-hulman.edu/~herniter/Data_Sheets/LM2577.pdf
I think in the final model I would like an adjustable regulator and a few preset switches for common voltages.

Then current is a different question, with adjustable voltage, is there a way for me to also regulate the current?

Thanks for the advice!

-Phil

2. ### gerty AAC Fanatic!

Aug 30, 2007
1,153
304
Wow 100 amps, isn't that a little overkill. How much current do you need? The datasheet for a lm317 will show you how to use one as a voltage regulator and/or current regulator, provided you don't exceed the current limitations.

3. ### pjhart Thread Starter New Member

May 16, 2013
3
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The input-to -output differential say 3<x<40. Does that mean the difference in input and output voltage will be at least 3 volts and not more than 40? In that case I woudn't be able to do 10.8-16.8 volts, and it would max at 53.8?

And to compensate for amperage I would use multiple ICs? The 100 amp inverter was a free-bee from when an old job went out of business. I was originally going to use a computer power supply, until i remembered this goliath.

4. ### wayneh Expert

Sep 9, 2010
12,100
3,034
If you want higher voltages than the supply, you need a DC-DC converter, a boost. For lower voltages that is also true (a buck), although you could also use the linear options such as LM317. In both cases, getting enough power for a lab bench is easy (again, the LM317 for instance) but getting anywhere near the 1300 watt capacity of your supply will require serious design. Just because you can doesn't mean you should. Do you have any plans to actually use all that juice?

5. ### gerty AAC Fanatic!

Aug 30, 2007
1,153
304
You still haven't told us how much current you need.

6. ### pjhart Thread Starter New Member

May 16, 2013
3
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The inverter has five modules in it at 20 amp each I think, so I could step it down easily.

I don't have a specific project for this, but we are making this power supply for a laser that we are currently working on. We started by breaking down a laser pointer, and are replacing components of it to better understand how it functions(and because its cool).

I was more looking to make a generic voltage/curent selector etc for random testing and tinkering. Would it make sense to try and get it down to like 40 amps before trying to change the voltage around?

7. ### gerty AAC Fanatic!

Aug 30, 2007
1,153
304
In my opinion, even 20 amps is a lot, but then again we don't know what your needs are. A small laser pointer should only use a few milliamps at perhaps 3-5 volts.
To give you an example, the bench power supply I use the most is 0-15vdc at 3 amps, of course everyone's needs are different.