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simple current limiting to 2A with TIP122

azadfalah

Jul 17, 2016
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hello friends

i need Limit Current to 2A Like This circuit
When the current through 2A RED LED ON .

photo_2016_08_13_14_46_36.jpg


Please help to get the circuit diagram .

Thanks
 

Arouse1973

Adam
Dec 18, 2013
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Why don't you just use that circuit? Otherwise we need wayyyyy more information. What is the load you are driving, what voltage, that sort of thing.
Adam
 

azadfalah

Jul 17, 2016
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Thanks for the answer

Voltage = 24V
Load= Seven numbers external 7segment
i need current limit like this circuit Very simple with a LED display
 

Arouse1973

Adam
Dec 18, 2013
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Do you need constant current or a current limiter. Very different things.
Adam
 

azadfalah

Jul 17, 2016
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Thanks very much for your ideas

But i want the circuit schematic in image

Who can help me
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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How large is the heat sink on your TIP122 considering it may dissipate 48W?
 

azadfalah

Jul 17, 2016
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How large is the heat sink on your TIP122 considering it may dissipate 48W?

I realized
This is not limiting 2A
I can not test this circuit Because is working
Do you think that how many watts?
can help to find the diagram?
 
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(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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I can guarantee that is the number of watts if your TIP122 is driving 2A into a short from a supply at 24V.

The heat sink will likely be about half the size of your fist.

If this is really what you want, I can point you to a circuit (in fact, you may be able to find one similar in the LED resource on this site)

If I said you had to calculate a resistor which would drop 0.7V at 2A, could you do that?
 

azadfalah

Jul 17, 2016
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I have think that each segment will take 30 mA
Seven segment was a 210 mA current I have 8 Seven Segment result 1680 mA
and a current limiting 2A need
So how do the Chinese Limit the current with TIP122 without cooling ?
Possible short circuit too much
But at the time of short circuit LED short circuit on the field and we realized getting short-circuited
 
Last edited:

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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What is the TIP122 doing? In a multiplexed display it will either be driving a max of 30mA or 240mA depending if it is a row or column driver. In either case it shouldn't be shorted out and if it is, you've done something badly wrong.

Is it a LED display? If so, why the 24V supply?
 

azadfalah

Jul 17, 2016
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What is the TIP122 doing? In a multiplexed display it will either be driving a max of 30mA or 240mA depending if it is a row or column driver. In either case it shouldn't be shorted out and if it is, you've done something badly wrong.

Is it a LED display? If so, why the 24V supply?

this is elevator 7 segment display and we have 8 floor and 8 7 segment too .
In step installing Possible short circuit too much (24V With a,b,c,d,e,f,g) and when +24 connected to a(7segment sc) one LED in Circuit on and we realized getting short-circuited .

i need a circuit limit current to 2A have Signal LED TOO :)
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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I don't understand.

Are you driving 8 x 8 digit 7 segment displays?

Is the TIP122 the driver for the segments or for the digits?

Remember that in a multiplexed display only a single digit is on at any time. The digits are scanned through quickly to give the illusion that all are on.
 
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