Long time lurker, first time poster, and a little green when it comes to electronics :-)
I have a little problem that is confusing me and I am hoping someone may be able to provide some direction.
I have a basic circuit (Arduino controlled), that outputs a PWM signal, this connects to a PCA9685, which in turn connects to a N-Channel MOSFET (FQP30N06L), which has a 12 volt power supply (DRP012V100W1AA - DIN Rail power supply) feeding an MR16 12v Led.
The circuit has a resistor (10k) between the gate and source on the MOSFET, the led and power are on the drain, with the source grounded (and the other end of the led also connected there).
All seems to work nicely - I do not have a scope, but the voltages seems to flow nicely up and down when I measure with a multimeter, and overall the led seems to dim and get brighter as would be expected ..
.. but ..
When I drop the PWM cycle down the led gets dimmer, then does a sudden drop in brightness, and then doesn't fade down all the way to nothing ..
My initial thought was the pulse frequency - so I have dropped this to 100Hz, no change. Then I started thinking it may have to do with the led power driver - do I need one or not - but after some reading I concluded that standard downlight leds already have a driver, so current shouldn't be a problem. Then I wondered if the led I had wasn't dimmable - tried some different ones - no changes .. and the fact it does actually dim overall seems to indicate that it is dimmable.
I will post an actual circuit later - just need to draw it up - its all on the breadboard at the moment :-)
(slight mistake - its not PWM coming from Arduino, but I2C)
My guess is that I am forgetting something silly (a resister between the LED and the mosfet?).
Anyhow, if anyone can suggest an avenue of investigation, it would be VERY much appreciated.
Thanks & kind regards,