I am trying to make a PID controlled head block, but have had two mosfets croak. Can somebody verify that my wiring and code are correct? I have pwm voltage coming in and out of the mosfet driver, but it if the same voltage, so now I am wondering if I damaged the driver and the mosfets or just the mosfets, and what the problem is.
project_code.ino (3.59 KB)
The little tiny breadboard at the bottom is so funny. This is not an acceptable way to draw a schematic here.
Yeah, a person with a PhD drew this, and it wasn't me. The code was attached.
Please supply a circuit diagram that identifies what the components are, not how they look like.
Also explain what's the heating element, and how you drive it.
What is the output voltage of the AC/DC power supply at the upper right?
12V 30 amp supply. The mosfet is rated 12V 25A. I was assigned these parts for a project.
Parts are as follows:
Mosfet driver is a TC4427
...I have pwm voltage coming in and out of the mosfet driver, but it if the same voltage, so now I am wondering if I damaged the driver and the mosfets...
The TC4427 should bump the PWM voltage to 12V (in this case) so there's a problem there. What does the output look like when not connected to the MOSFET board?
If the MOSFET is not being driven hard enough it may be more resistive than it would otherwise be and will get hot for higher drain currents. If the heating is bad enough the FET may fail.
You may want to consider adding some capacitors between the VDD and GND pins of the 4427 per the datasheet, figure 4:
So I have been messing with it and my FET will not turn on without 12V (pwm=2000) into the driver as opposed to limiting the PWM range to 0-255. So I am guessing the driver is fried.
jscates00:
So I have been messing with it and my FET will not turn on without 12V (pwm=2000) into the driver as opposed to limiting the PWM range to 0-255. So I am guessing the driver is fried.
Do you have an oscilloscope? If so, can you capture the input and output waveforms?
I was assigned these parts for a project.
So it's your course work!
Mark
Still you really should draw a complete schematic of the system.
How is it built up exactly? Breadboard or proper PCB or dead bug style?
Which exact FET type?
holmes4:
So it's your course work!
So what if it is? Why can't using a forum be a legitimate use of all the resources available to us? As long as the asker cites the forum as a source, and doesn't fall foul of the "own unaided work except as cited" kind of rule, just like with any other source, what's wrong with it?
It's your prerogative, as always of course, to assist or not to assist.
Hi
Your code uses an LCD screen, is that connected so you can read what the setpoint and heater temperature are?
Do you have or have access to a DMM?
Thanks.. Tom... 
