About the broken connections, I don't really care, just good that we know it's a manufacturing defect and not something with the design.
On another matter, I've been having problems with the ADC ever since. There is very high variance; for example I can see the ADC reading jump from 82/1024 (235C) to 88/1024 (230C), in less than half a second, then back. From what I've observed, it's caused by FETs being switched. So for example if I only drive one heater it's going to be kind of okay, but if I drive two at the same time, after they've stabilized and running at partial power, there is higher variance in readings.
My theory is that as FETs are turned on/off, the (12V) supply voltage changes, and so do the 5V and 3.3V. The 3.3V change, due to the capacitor in parallel with the thermistor, causes the ratio of thermistor voltage to 3.3V supply voltage to change (which is what the ADC is measuring). The error lasts while the capacitor charges/discharges. Anyway, in my setup, I observe:
- With bed OFF: 12V:14.62V 5V:4.99V 3.3V:3.26V
- With bed ON: 12V:14.18V 5V:5.05V, 3.3V:3.32V.
And yet I'm only seeing a 2% voltage change, while 82-->88 is much more (7%). Plus, considering these voltage measurements are for switching the bed, and ADC measurements were done while the bed was off an only extruder heaters were running, there has to be more going on.
Has anyone else had such problems? It could be that my (SainSmart) Due is defective. Because they did use a different 3.3V regulator then in the official Arduino (AMS1117 instead of NPC1117). I've ordered an original Arduino but it'll be a while before I get it.
On another matter, I've been having problems with the ADC ever since. There is very high variance; for example I can see the ADC reading jump from 82/1024 (235C) to 88/1024 (230C), in less than half a second, then back. From what I've observed, it's caused by FETs being switched. So for example if I only drive one heater it's going to be kind of okay, but if I drive two at the same time, after they've stabilized and running at partial power, there is higher variance in readings.
My theory is that as FETs are turned on/off, the (12V) supply voltage changes, and so do the 5V and 3.3V. The 3.3V change, due to the capacitor in parallel with the thermistor, causes the ratio of thermistor voltage to 3.3V supply voltage to change (which is what the ADC is measuring). The error lasts while the capacitor charges/discharges. Anyway, in my setup, I observe:
- With bed OFF: 12V:14.62V 5V:4.99V 3.3V:3.26V
- With bed ON: 12V:14.18V 5V:5.05V, 3.3V:3.32V.
And yet I'm only seeing a 2% voltage change, while 82-->88 is much more (7%). Plus, considering these voltage measurements are for switching the bed, and ADC measurements were done while the bed was off an only extruder heaters were running, there has to be more going on.
Has anyone else had such problems? It could be that my (SainSmart) Due is defective. Because they did use a different 3.3V regulator then in the official Arduino (AMS1117 instead of NPC1117). I've ordered an original Arduino but it'll be a while before I get it.