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Topic: Transistor help please (Read 171 times) previous topic - next topic

cyborg8274

I wanna know if I should use resistor while connecting to base of TRANSISTOR TIP120 from arduino digital pin or is it okay to directly connect, coz I tried with BC547B transistor and it got heated up.

slipstick

Have you ever seen a published circuit with a TIP120 connected to an Arduino without a base resistor? So what do you think?

Steve

cyborg8274

NO, i haven't. I'm still learning and there's no need for sarcasm. You could just not reply at all and someone else who's more polite will surely help.

vinceherman

cyborg8274, don't chase off the help. 
While Steve might have included his wry sense of humor in his reply, it was still accurate and helpful.




cyborg8274


slipstick

NO, i haven't. I'm still learning and there's no need for sarcasm. You could just not reply at all and someone else who's more polite will surely help.
If you Google "TIP120 Arduino" (as I did) you will find loads of circuits showing a TIP120 connected to an Arduino digital pin. That way you would have had your answer much quicker, without waiting for anyone here.

If you want an even more direct answer...yes you need a resistor. The value will depend on what it is that you are switching.

Steve

Wawa

Have you ever seen a published circuit with a TIP120 connected to an Arduino without a base resistor?
Yes.
Unfortunately in an official tutorial ON THIS SITE.
Same long-standing mistake as the capacitor in the shift register tutorial.


A 1k base resistor for a TIP120 darlington is OK for collector currents up to about 1Amp
For higher collector currents (up to 4Amp), you can drop that to 220ohm (so 470ohm for ~2Amp).
The TIP120 gets hot >= 1Amp collector current, so needs a heatsink.
Better to switch to a logic level mosfet, especially for collector currents > 1Amp.
Leo..

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