# voltage regulator with high current output

#### childs72

Joined Jul 3, 2005
22
hi all, i need a voltage regulator that able to provide high current up to 10A+ as supply for part of my project, meanwhile my project output should be a portable device. I would like to know about any circuit or components that might help..... thx a lot 1st

#### Papabravo

Joined Feb 24, 2006
21,264
Originally posted by childs72@Mar 13 2006, 01:34 PM
hi all, i need a voltage regulator that able to provide high current up to 10A+ as supply for part of my project, meanwhile my project output should be a portable device. I would like to know about any circuit or components that might help..... thx a lot 1st
[post=14941]Quoted post[/post]​
As with most one sentence requests, we have no idea what input voltage we are working with. We have no idea what output voltage we are working with. If it is to be portable how much weight can you tolerate?

PLEASE PLEASE PLEASE. Try to construct a complete paragraph detailing your requirements. Without such a definition, there is no way we can formulate a design, and there is no way for you to evaluate what "done" means.

#### childs72

Joined Jul 3, 2005
22
well actually there will be 2 types of voltage regulator with high current output i need. 1 positive voltage source n 1 negative voltage source to produce an output at +/-15V with current varyng from 0-10A depending on the precision current sink/source as load. I intended to use dc 9v battery as input voltage to the regulator since i need a very portable device that if possible weight like a normal multimeter.

Since i am newbies in electronics porject, i hope u guys can kindly give some advices or comments on d solution or d project itself. thx

#### n9352527

Joined Oct 14, 2005
1,198
I don't think small PP3 9V battery would be able to supply 10A. Unless you are referring to a super big 9V battery, which I've never seen.

10A at +/-15V supply would not be small and weight like normal multimeter. That is 300W at full power!

You would need a big battery which would weight quite considerable (like 12V car battery), and not a regulator, but a robust 300W DC-DC converter to convert the 12V to +/-15V at 10A. This is not an easy design.

Or you could make your input voltage higher (use a few batteries in series) in order to use simpler linear regulators.

#### thingmaker3

Joined May 16, 2005
5,083
Six AA batteries will last more than twice as long as a 9v battery. Even six AA alkalines 's would last only five minutes at the power levels proposed.

#### Papabravo

Joined Feb 24, 2006
21,264
Originally posted by childs72@Mar 13 2006, 01:34 PM
hi all, i need a voltage regulator that able to provide high current up to 10A+ as supply for part of my project, meanwhile my project output should be a portable device. I would like to know about any circuit or components that might help..... thx a lot 1st
[post=14941]Quoted post[/post]​
A deep cycle marine battery is designed for a steady current drain over an extended period of time, as would be the case with a trolling motor. I used one for about 12 hours to power a 100 W amateur radio transceiver. The fully charged voltage was about 12.61V and the fully discharged voltage was 11.72. This voltage did not need to be regulated since the radio can operate over a fairly wide DC range.

I would not recommend walking around with one of these batteries in a backpack, but it did fit in the well of the passenger seat of my truck very nicely.

#### childs72

Joined Jul 3, 2005
22
Originally posted by Papabravo@Mar 15 2006, 04:48 AM

....I would not recommend walking around with one of these batteries in a backpack, but it did fit in the well of the passenger seat of my truck very nicely.
[post=14990]Quoted post[/post]​

wow.... i like this suggestion but i would like to consider n9352527 suggestion for my design.... ^^

#### childs72

Joined Jul 3, 2005
22
Originally posted by n9352527@Mar 14 2006, 11:48 PM
I don't think small PP3 9V battery would be able to supply 10A. Unless you are referring to a super big 9V battery, which I've never seen.

10A at +/-15V supply would not be small and weight like normal multimeter. That is 300W at full power!

You would need a big battery which would weight quite considerable (like 12V car battery), and not a regulator, but a robust 300W DC-DC converter to convert the 12V to +/-15V at 10A. This is not an easy design.

Or you could make your input voltage higher (use a few batteries in series) in order to use simpler linear regulators.
[post=14972]Quoted post[/post]​

Actually the voltage output is not d critiria of my project, i need to hav high current controllable by d precision sink/source of my design. i juz assume 15v is able to provide such a high current up to 10A. And d +/-15v supply is not working simultaneously, hence d circuit will work at maximum about 150W at a time (still very high).

By the way, u suggested using higher input voltage (use a few batteries in series) in order to use simpler linear regulators, but in this case it will cause more power consumption right? And will it affect d size n weight as well as heat prob of the circuit?

#### childs72

Joined Jul 3, 2005
22
And i think i missed some points on my design, the maximum current will only be drained for a very short period in tens of milieseconds controlled by microcontroller. So i think d problem of power consumption may can be mitigated.

#### windoze killa

Joined Feb 23, 2006
605
Originally posted by childs72@Mar 15 2006, 01:53 PM
And i think i missed some points on my design, the maximum current will only be drained for a very short period in tens of milieseconds controlled by microcontroller. So i think d problem of power consumption may can be mitigated.
[post=15003]Quoted post[/post]​
I still think you may have trouble drawing that much current from a battery of that size. For example, just because a battery is 1000mAh and can supply 1A for one hour before losing enough charge to be useless does not always mean you can draw 2A for 30 minutes or 4A for 15 minutes. If the internal wiring of a battery has wires that can only handle 1A then thats about the limit. I know that if the current draw is very short you can exceed the rating it will still shorten the life and possibliy cause catestrophic failure.

#### n9352527

Joined Oct 14, 2005
1,198
Originally posted by childs72@Mar 15 2006, 03:49 AM
Actually the voltage output is not d critiria of my project, i need to hav high current controllable by d precision sink/source of my design. i juz assume 15v is able to provide such a high current up to 10A. And d +/-15v supply is not working simultaneously, hence d circuit will work at maximum about 150W at a time (still very high).

By the way, u suggested using higher input voltage (use a few batteries in series) in order to use simpler linear regulators, but in this case it will cause more power consumption right? And will it affect d size n weight as well as heat prob of the circuit?
[post=15002]Quoted post[/post]​
If the voltage is not critical, then don't use regulator. Just make sure that the voltage is able to supply the 10A needed at maximum load resistance, e.g. maximum load resistance with 12V supply would be 1.2 ohm, assuming there is no drop at the current sink circuit.

If you are sure that this is a pulsed current design and the duty cyle is permissible, then you could consider using a large capacitor or several of them to sustain the pulse and then slowly charge them back up.

#### childs72

Joined Jul 3, 2005
22
now i hav an idea of using an ac-dc adaptor to draw power from a household electric supply n convert it to dc, hoping that this will be able to produce high enough current.

however i am having trouble searching for the complete circuits of the adaptor though i was told it is a simple circuit (which i seemed recently, consisted of 1 full-bridge rectifier, 1 resistor, 1 cap n 1 LED) but i am not sure what is d full configuration n whether i missed any components.

#### windoze killa

Joined Feb 23, 2006
605
Originally posted by childs72@Mar 19 2006, 08:46 PM
now i hav an idea of using an ac-dc adaptor to draw power from a household electric supply n convert it to dc, hoping that this will be able to produce high enough current.

however i am having trouble searching for the complete circuits of the adaptor though i was told it is a simple circuit (which i seemed recently, consisted of 1 full-bridge rectifier, 1 resistor, 1 cap n 1 LED) but i am not sure what is d full configuration n whether i missed any components.
[post=15176]Quoted post[/post]​
Building a 10A power supply will require a pretty big transformer. The rest of the parts are going to be pretty meaty as well. The one you have described is probably the most simple unregulated supply you could imagine. As you have stated you have a microcontroller you will definately need a highly regulated supply. You will need a decent linear or switch mode regulator chip. There are plenty of designs on the net for high current supplies. National Semiconductor and Linear Technologies both have design tools you can use to design your supply. They even tell you the brand part numbers for the components.

Have a look at these and see what you think.

#### childs72

Joined Jul 3, 2005
22
Originally posted by n9352527@Mar 15 2006, 06:35 PM
If the voltage is not critical, then don't use regulator. Just make sure that the voltage is able to supply the 10A needed at maximum load resistance, e.g. maximum load resistance with 12V supply would be 1.2 ohm, assuming there is no drop at the current sink circuit.

If you are sure that this is a pulsed current design and the duty cyle is permissible, then you could consider using a large capacitor or several of them to sustain the pulse and then slowly charge them back up.
[post=15016]Quoted post[/post]​

I try to use a cap of 100u n a 9V battery for 500mA precision pulse current sink(which will draw no current under normal condition n draw pulse of max 500mA if a pulse is inserted), but somehow it can onyl give d pulse current up to around 250mA, how would u recommand me to improve this? by using larger cap? how should i choose my cap in this case for higher current capability?

#### kubeek

Joined Sep 20, 2005
5,796
Originally posted by childs72@Mar 24 2006, 09:37 AM
I try to use a cap of 100u n a 9V battery for 500mA precision pulse current sink(which will draw no current under normal condition n draw pulse of max 500mA if a pulse is inserted), but somehow it can onyl give d pulse current up to around 250mA, how would u recommand me to improve this? by using larger cap? how should i choose my cap in this case for higher current capability?
[post=15379]Quoted post[/post]​

The current depends on the load, so for 9V it has to be lower than 18ohms. Also try to use a bit higher capacity, like 10,000uF.