Powering multiple 12V LED strips and connecting to LilyPad Arduino USB

Hi there,

I’m currently trying to work out how to connect multiple 12V LED strips to a LilyPad Arduino USB (operates at 3.7V).

I was thinking that MOSFETs would be the answer, but I am not sure how to then connect all the MOSFETs to one power source.

This is all to be part of a headdress (photo attached!)

Many thanks for your help - it’s greatly appreciated!

R

You need logic level MOSFETs that work at 3.7V (most will only guarantee
performance down to 4.5V).

Use n-channel MOSFETs in low-side switch configuration. Thus +12V goes to
LED strip +ve, LED strip -ve goes to MOSFET drain, MOSFET source goes to 0V(gnd)
on the 12V supply.

Also connect source to LiliyPad ground, gate via 150 ohm resistor to Lilypad pin.

Keep the high current wiring from 12V supply separate from the Lilypad.

For multiple strips and MOSFETs just wire them all as above, different Lilypad pin
to control each.

Awesome, thank you so much for your help - very clear.

I wired everything up today with what I had to hand and I've got it all working but the lights aren't as bright as they could be... I think I need to maybe use different MOSFETs or it's because I need a resistor between the gate and the LilyPad?

I'm using FQP2N60C MOSFETs, but have no resistors in the circuit. I've also simplified the design, so it just uses 2 LilyPad pins; 3 strips are connected in series on one and 4 strips are connected in series on the other. I'm using one 9V and 2*AA batteries to power the strips.

Any advice on which factor could be making the lights not so bright would be really helpful. Thanks!

That's a terrible MOSFET.
Rds with Vgs at 10V is very high, 3.6ohm.

You need a Logic Level MOSFET with Low Rds:
http://www.digikey.com/product-search/en?vendor=0&keywords=aoi516
Rds = .01 ohm with Vgs = 4.5V
http://aosmd.com/res/data_sheets/AOI516.pdf
Practically just a piece of wire.