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Topic: what transistor to use as a switch from arduino to 12v led light strip  (Read 1 time) previous topic - next topic

beamer16

im quite a newbie with the maths side of circuits so hoping for a bit of advice.

i have a led strip containing 36 blue leds that consume 3.60v 20ma each (im not sure on how there connected internally as its a sealed unit),
 the circuit that currently controls the Blue leds runs from a 14v power source and outputs a peak of around 12.5v to the led circuit when
the brightness is on full.

my plan is to control the leds with my arduino mini (on and off), i intend to use a transistor to switch them via gnd but i can not understand
 how to work out what transistor is suitable and what value resistor to use for the base to fully saturate and hopefully produce 12.5v output
like the original controller when on full power.

PaulRB

Hi and welcome.

The best transistor for the job would be an N-channel power MOSFET with a logic-level gate. Most commonly available would be IRL520, but there are many other suutable models such as Stp36nf06l.

MOSTFETs don't have a "base" but rather a "gate". A lowish value of 100R - 300R between the gate and arduino pin would be fine, it is not critical. However, its also a good idea to put a 10K between the gate and 5V or 0V to make sure the MOSFET is properly on or off while the Arduino resets.

Paul

Paul__B

However, its also a good idea to put a 10K between the gate and 5V or 0V to make sure the MOSFET is properly on or off while the Arduino resets.
Or more accurately, between the Arduino output and ground, before the 220 Ohm resistor to the gate.

beamer16

Hi and welcome.

The best transistor for the job would be an N-channel power MOSFET with a logic-level gate. Most commonly available would be IRL520, but there are many other suutable models such as Stp36nf06l.

MOSTFETs don't have a "base" but rather a "gate". A lowish value of 100R - 300R between the gate and arduino pin would be fine, it is not critical. However, its also a good idea to put a 10K between the gate and 5V or 0V to make sure the MOSFET is properly on or off while the Arduino resets.

Paul
Thank you for the warm welcome and the very helpful response.

i am only able to get the BD675A from ebay, i can wait for it to be delivered but if you no of an equivalent mosfet that i could source from maplins that would be great.


PaulRB

an equivalent mosfet that i could source from maplins
Maplin don't do that sort of thing, haven't done for years!

Try these people, I have used them before: Rapid Electronics but watch out in case there is a minimum order value!

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