Switching 120mA 12v DC from Spark Core without a relay


Is this possible? I was given to understand that it might be possible to do with a transistor or a MOSFET?

I really don’t want the faff of wiring up a relay and the transistor to control it if I can avoid it - I would really much rather just control the LED (for this is an LED I am trying to switch) as directly from a spark pin as I can.

Would a 2N2222 transistor be my friend?


2N2222A seems fine with Ic @ 1.0A

Or consider an LED driver perhaps?


Sure, You should be able to use a NPN transistor for low side switching or a PNP transistor for high-side switching.

[Edit] I really like this java circuit simulator. It makes checking questions like these a breeze!

Link to circuit: link. Link to simulator alone: link


Side question ; are you sure your led is 12v?

LEDs are diodes, they have a voltage drop. There really isn’t such a thing as a “5V LED” or “12V LED”. As long as you appropriately limit the current through an LED you can essentially hook them up to any voltage source

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My whole life (study so far? Haha) was a lie!

Jokes aside, I didn’t know that. Thanks!

Glad I could help. Electronics are confusing; I’ll admit that right away. I’ve really enjoyed this book: Practical Electronics for Inventors. I was recommended it by one of my ECE friend and now I highly recommend it.


I will try to get a hold of that, looks nice!

I bought the book - it is amazing - but incredibly dense in terms of theory/formulae. I guess I have some basic reading to do first before tackling this book.


Yes, it’s quite detailed and formula heavy but I think it does a good intro job as well. Good luck. Glad you like it

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