Best NPN transistor to use for a 24v relay

Hi there

I have a 24V 5 pin automotive relay and i would like to power it's coil via a transistor connected to my arduino and 24V.
What would be the best transistor for this application?

Relay coil 24V DC, 200mA

I would use a logic level N channel MOSFET but many NPN transistors would work plus a base resistor of some 220 - 470 Ohm.

It's hard to find one that can not be used therefore.

What's your "best" criterion? Price? Color?

1 Like

I need it to be very reliable ie not fail within a year.
I am putting a flyback diode across the relay so it should be protected from reverse voltages.
I read that the 2N2222A is pretty good.

Almost all "correctly used" transistors don't fail in just one year.

I use the 2N3404 and will until I die or run out, looking like 50/50 on which comes first. :expressionless:

Def gonna leave some 2N3906s behind.

a7

2N2222A should work well with 390 or 470 Ω base resistor and a 5 volt Arduino, just be sure to get collector and emitter leads right.
https://media.digikey.com/pdf/Data%20Sheets/NXP%20PDFs/2N3904.pdf

That's not what a flyback diode does.
It protects the transistor from a higher voltage when the relay turns off.
Leo..

I would suggest you post a schematic.

For FETs you would need a logic level device.

Check the data sheet for maximum current.