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Arduino to control 75w halogen lamp as a on/off switch. Answered

I am using a tip120 but it gets too hot, so i got a tip3055 is it going t be fine?

what do you guys suggest?

need any other infomation?

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steveastroukBest Answer (author)2010-12-05

Yes, a TIP121 is too small for the current - assuming this is a 12V halogen. Personally, I'd just use a logic level Mosfet, like an IRL540, rather than a BJT.

Steve

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gioruchan (author)steveastrouk2010-12-05

yes, it's a 12v 75w halogen lamp.

what do you think about the tip305it dissipates 80w.

I am a begginer and have little knowledge of electronics...

(what's the difffernece between a msfet and a bjt?)

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steveastrouk (author)gioruchan2010-12-05

You really don't want to dissipate 80 W if you can help it. The Mosfet will waste much less heat - like 0.6 W when its on.

A mosfet uses a VOLTAGE on its GATE terminal to control current flowing between source and drain.

A BJT uses a CURRENT on its BASE terminal to control current flowing between collector and emitter.

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gioruchan (author)steveastrouk2010-12-05

ok, I tried to make it work now i have two questions:

1) transistore gets way too hot, is the mosfet not going to heat up?

2) transisotr does not get signal from arduino.... feels liek it's too weak. I tried to touch the base pin with a 9v batgtery and it works fine, i tired wit 5v and it works fine.... what can i do to amplify the power of a pin?
maybe use a smaller transisotr that connnected to a 5v source?

thank you

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steveastrouk (author)gioruchan2010-12-06

Why did you remove the best answer that you'd given me ?

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steveastrouk (author)gioruchan2010-12-05

No, the MOSFET won't get as hot.

Put a resistor from +5 to the pin of the arduino, then to the base/gate terminal- something like 330 Ohms should work nicely.

Arduino pins don't source much current.

Steve

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