Are there any advantages/disadvantages choosing a transistor over a mosfet in this particular case? if not, I feel like buying some mosfets for the job.
I believe that both a mosfet or a transistor would allow me to still operate the driver with a PWM signal?
What values should I look out for when choosing a N-type mosfet for the job?
where ... would I apply the PWM signal coming from the Arduino? - is it just where I normally would connect the Arduino, that would be the control-line following his circuit
I built the following circuit:
f anyone knows why, I would like to know what can cause that my led-pcb isn't actually drawing 350mA when that's what I calculated the RS-resistor for
You have two outputs connected together, a great way to screw up components.
the best position to inject the PWM pulses is the gate of the MOSFET. The gate resistor RG will act as a pull-up resistor for the PWM generator.
I played around with the constant current driver circuit I found on Pcbheaven, because it's build around a mosfet like I'm using
I've calculated the RS-resistor by using the BC337's Vbe-value which is 1.2V following the datasheet.
If anyone knows why, I would like to know what can cause that my led-pcb isn't actually drawing 350mA when that's what I calculated the RS-resistor for :-)
The 1.2 Vbe (I am assuming your 2.1 above was a typo) is the Max on the datasheet, not typical. I actually suspect it is less than 1V.
As far as I can see from the circuit in #33 to the circuit in #36 I'm using is the resistor at the control-line in #33. If I add such resistor (10k?) to my circuit, I should be good?
As I described I was playing around with the constant current driver circuit found at Pcbheaven here:Constant current driver
And then, on this page the guide says thatFound in the bottom of the page: PWMI believe I did it right following the guide at PCB heaven, but as far as I can tell from your comment, it isn't right at all. I would like to know what to do then.
Remember that the PWM controller i use sinks current and does NOT source. The base of the transistor grounds on every pulse of the generator, thus the transistor turns off completely, turning off the LED as well.