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uln2003 data sheet question.

Dude22

Mar 30, 2012
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500ma limiter

Hi, Is there any way to lower a 12 volt supply to 500ma when it starts around 10amps???
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Hey Dude, what do you mean "starts around 10A"?
 

Dude22

Mar 30, 2012
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On this: http://www.datasheetcatalog.org/datasheets/120/489337_DS.pdf data sheet It says: "The collector-current rating of a single darlington pair is 500mA.The darlington pairs may be parrlleled for higher current capability" How would you do this???

NOTE: In my other recent question I ask if there is any way to lower 10 amps to 500ma, If I can find a way for the uln2003's to allow higher then 500ma, this would be the better solution.
 

CocaCola

Apr 7, 2012
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Note that you can group them together for more than 500mA but the chip itself maxes out at about 1200mA total, so you can basically only parallel 3 outputs and get 1200mA per chip, might as well parallel all outputs at that point to better distribute the load across the chip... If you want to switch 10 amps you will need give or take 9 or 10 of these chips all paralleled together... You are far better off just getting a single larger package transistor that can handle the full 10A by itself...
 

CocaCola

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A circuit will only draw what it needs, if it needs 10A and you limit it to 500mA chances are it's going to not function properly...
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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OK, now it's all merged. But even so, we still don't really know what you want to do.

Perhaps if you tell us what it is that you want to do then we can help you.

What you have done is come up with a few possible solutions and you're asking us about them without telling us what the actual problem is. Whilst we can address the things you have posted, experience tells us that to do so may leave you with something that won't work in whatever application you have.
 

Timescope

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I think he needs a current limiter circuit. 10 amps is not experiment friendly.

Timescope.
 

CocaCola

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I think he needs a current limiter circuit. 10 amps is not experiment friendly.

My guess is that he is attempting to force something to operate at a lower current, and there is likely a better approach that can be taken...

As I said previous a circuit only draws what it will need, excess available Amps from the power supply is rarely a concern of the circuit design... The only time a power supply that can pump 10A would NOT be 'experiment friendly' is if you have shorts and faults in your circuit that would smoke faster with the higher current... Other wise it's generally a positive thing as you it will be able to supply the necessary current for multiple things and don't have to worry about starving the circuit... Some medium sized audio amplifiers and things like motors can easily need that much current...
 

CDRIVE

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I think he needs a current limiter circuit. 10 amps is not experiment friendly.

Timescope.

I too think he's asking for a current limiter.

Anyone ever wonder why we spend better than 50% of our time playing mind readers? :rolleyes:

Chris
 

gorgon

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Anyone ever wonder why we spend better than 50% of our time playing mind readers? :rolleyes:

Chris

Yes, I think we all want to be soothsayers, and make it a competition between us to be the best. :D


TOK ;)
 

(*steve*)

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I too think he's asking for a current limiter.

But (and this is not for CDRIVE's benefit) the load may actually require 10A startup current and so we need a change that will allow that current to be supplied.

It may be as simple as a capacitor, but it may also require some pass elements to be looked at.

Or it may be that the 10A indicates a fault in the load or it being miswired, etc.

If we give the OP a solution to the wrong problem, it's not going to help (and may cause damage).
 

CDRIVE

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Yes, I think we all want to be soothsayers, and make it a competition between us to be the best. :D


TOK ;)

Honestly, only 50% of what we do here is actually giving advice, guidance and schematics. The other 50% of the time is spent thinking... "What the hell did he say?!?!".

Chris
 

CDRIVE

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<snip>If we give the OP a solution to the wrong problem, it's not going to help (and may cause damage).

Ah, but there's the big ? Does anyone really know what the question is? I'm just going through the motions of that 50% I mentioned. :D

Chris
 

gorgon

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Honestly, only 50% of what we do here is actually giving advice, guidance and schematics. The other 50% of the time is spent thinking... "What the hell did he say?!?!".

Chris

Sometimes it is more like 90% thinking :rolleyes: And the rest is guesstimates :confused:

Chris. I tried to make a humorous point, No offence intended.

TOK ;)
 
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CDRIVE

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Yes, I think we all want to be soothsayers, and make it a competition between us to be the best. :D


TOK ;)

Sometimes it is more like 90% thinking :rolleyes: And the rest is guesstimates :confused:

Chris. I tried to make a humorous point, No offence intended.

TOK ;)

Take offense? Heck no. I too think it would be fun to have a contest. I'm semi retired but if I win I'll modify my all my company documents to include "& Psychic Medium". :p

Chris

Oh, I almost forgot.. I'm a big fan of old 50's - 60's vintage Si-Fi. Did you know that the Brits made a movie by the title "Gorgon"? ;) I think it ate London! :D
 

gorgon

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Oh, I almost forgot.. I'm a big fan of old 50's - 60's vintage Si-Fi. Did you know that the Brits made a movie by the title "Gorgon"? ;) I think it ate London! :D

Well, I took my alias from an old Norwegian children's TV show from the 60's. http://en.wikipedia.org/wiki/Pompel_og_Pilt

Gorgon the janitor is one of the characters, and nothing to do with the Gorgon sisters from the Greek mythology.

TOK ;)
 

CDRIVE

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Oops my mistake. That should be Gorgo that ate Ireland but fortunately didn't damage the pubs. :D Probably short for Gorosaurus, a huge theropod in the Tyrannosaur family, though the critter depicted looked more akin to an Apatosaurus on steroids.

Uh, does anyone know where the OP went?

Chris
 
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