I have been working the last 4 month on a controller for a solar steam production. Starting from scratch and not being an freak, a added up A LOT of frustration up to now..
At this moment, many things work fine. I use a UNO to control several outputs and several inputs. As I am still debugging, the Arduino is usually 'fed' by my computers USB.
My big problem now is a 12V pump (700mA) which i control with a MOSFET (BUZ11). Its gate is connected to the Arduino's digital output via a 1k resistor and connected to GND via 100k. Its source is on GND and its drain is connected to the (-) side of the motor, the (+) side is on 12V.
What happens is that from time to time the MOSFET stays 'blocked' in the conducting position (motor pumping), even if the signal stopped. (It 'unblocks' after a few hours).
According to one friend, I added a diode between drain and GND to prevent the MOSFET from reverse voltage from the stopping motor. It didn't help.
According to a post in the forum, I added a diode between (+) and (-) side of the motor for the same reason. It didn't help.
Is the 100k resistor to big? What other ideas you have? It's quite annoying to have a pump which doesn't stop pumping water...
The second problem is that sometimes (usually when I plug a detector or anything to the system or even when I plug the USB cable to the Arduino) my computer shuts down. The only idea I have is that my Arduino pulls more current from the USB than allowed in these situations? Any other guess??
Thanks a lot, Michael in Mexico