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Topic: transistor gate does not respond to arduino (Read 1 time) previous topic - next topic


Common usage of "transistor" is usually to refer to a bipolar transistor (NPN or PNP) rather than a FET like the IRLB8721.
People say FET or MOSFET typically to distinguish.  However this may vary by culture.
[ I won't respond to messages, use the forum please ]


Thank you very much! 

I was joking to myself that perhaps another transistor would do the trick but I guess that isn't such a bad idea after all.  I am pretty sure I've got some of these in my parts bin but just in case I am going to order these:


think they will work?

I will also post a diagram as soon as I get home tonight.

That's a very high price for such a commonly avalible transistor.

1/10 the cost and free shipping:

If you don't like E-bay then


Tayda sells lots of common electronics parts for low costs.



Ok I installed the transistor that was suggested but I still cannot get the Arduino to turn the heat off and on.  When I put the wire that goes to the Arduino on +12VDC it turns off, and when it is not connected (or connected to the Arduino) the heater turns on.

I have included a schematic of what I have wired up.  I am still learning to use this software but all the grounds are common and the two +12VDC are actually on the same rail.
try not to lose that magic smoke


Have you really got a 1.11 Ohm resistor? If so that is way too low and will cause 12 Amps of current to be drawn through that bottom transistor.
Change that resistor to 1K.


Show us your sketch...
Prove to yourself the sketch is working (use a LED with 220R resistor on the o/p pin)
The way you have it in your schematic isn't the same as how you have it wired up!

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