simple current limiting to 2A with TIP122

[azadfalah]

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.

no we have 7 TIP122 in circuit and 1 tip122 limit current . we drive simple 1 7segment in floor we have (a.b.c.d.e.f.g) with common +24 and show number p to 8

Come on
i need a circuit limit current to 2A have Signal LED TOO

 

[(*steve*)]

I can't see where you get 2A from. 7 segments times 30mA is 210mA. A limit of 250mA would be fine.

Or just use a 500mA fuse.

 

[azadfalah]

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

You really do not care @(*steve*)

i don't want use fuse i want use current limiter

 

[(*steve*)]

You really can't explain what you're doing.

You say you need a 2A current limit, yet all the explanation I've been able to get out of you suggests that 1/8th of that current is sufficient (which, by the way, goes a long way to explain why someone would attempt it without a heatsink).

It seems that you don't understand what you're doing, and if that is the case, I'm not willing to lead you further astray.

 

[azadfalah]

8 Seven Segment are Parallel i dont want limit per segment or 1 7segment i want limit for total 8 7segment

Do not change issue You do not understand me
IF you have limiter 2A with Signal LED Offer it , otherwise Do not ideas

 

[(*steve*)]

http://jeelabs.org/2012/11/24/its-a-current-source/