Hi all,
I'm installing a set of stairs lights that light up each step one by one when you approach, then fade out after a set time. I've got the PIR sensors and code working (thanks again to those who helped) with some LEDs straight off of the GPIOs (with resistors) with PWM dimming but they are too dim to be useful and it's time to up the brightness. I have ordered some LEDs in flush mount housings from a camper van shop which I plan to use, assuming they are bright enough when they arrive. Obviously I need something in between the LEDs and the GPIOs to up the voltage. Digging about, I have the below circuit however I'd be really grateful if somebody could confirm a few things for me before I shop.
The LEDs are 12-14v, 0.06W, 5mA. I've assumed as they hook straight to a car battery, that resistor RL is in the fitting so I won't need to add it.
My transistor of choice is the 2N7000 with a max Vgs = 3V and max continuous current of 200mA. Datasheet is here-https://www.farnell.com/datasheets/2304304.pdf It's capable of more current than I need but I don't know if the lights I've got ordered will be bright enough so would like some headroom (a few 1000% seems sensible![:lol:]( "Laughing")
) in case I change for a higher power fitting.
So, my questions....
Phil
I'm installing a set of stairs lights that light up each step one by one when you approach, then fade out after a set time. I've got the PIR sensors and code working (thanks again to those who helped) with some LEDs straight off of the GPIOs (with resistors) with PWM dimming but they are too dim to be useful and it's time to up the brightness. I have ordered some LEDs in flush mount housings from a camper van shop which I plan to use, assuming they are bright enough when they arrive. Obviously I need something in between the LEDs and the GPIOs to up the voltage. Digging about, I have the below circuit however I'd be really grateful if somebody could confirm a few things for me before I shop.
My transistor of choice is the 2N7000 with a max Vgs = 3V and max continuous current of 200mA. Datasheet is here-https://www.farnell.com/datasheets/2304304.pdf It's capable of more current than I need but I don't know if the lights I've got ordered will be bright enough so would like some headroom (a few 1000% seems sensible
) in case I change for a higher power fitting.So, my questions....
- Is my circuit workable/correct?
- Do I actually need resistors Rg and Rs (I've read mixed opinions)?
- If so, how do I calculate Rg and Rs?
Phil
Statistics: Posted by philmulrain — Wed Jan 17, 2024 10:01 pm