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in reply to: Randomly Changing Settings #3998

Hi guys,

First of all, I’m sorry for the late reply.

When the setting changes occurs, is the unit connected to the front end software or it is running on a standalone mode?
The output port can only be changed through the front end software. If it not connected to the front end software, it could be a firmware bug causing the output to be changed. My initial hunch is saying there could be a memory leak during run time causing the setting to be changed as there are other settings that changed too.

Myself have been using the osPID Kit (taking turns with my reflow oven shield) to do the reflow job nearly every week and this is the first time I have came across this.

Anyone else is facing this issues besides Sand and Cracked?

[rocketscream]

in reply to: What inputs outputs are free? #4002

Using the on-board relay (on D5) and the thermocouple input (D10, D12, D13, A6 (permanently tied to thermistor amplifier output)), you’ll be left with:
– A4, A5 (I2C) on both card.
– A7 pure analog input on input card.
– D6 (PWM capable) on output card but you have to use the 3 pins jumper selection header to tap this IO.
– D2 (external interrupt capable) on both card.

[rocketscream]

in reply to: Panasonic IR Reflow Oven #3985

One of the best reflow curve I have seen!
Awesome.

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in reply to: Thermocouple grounding #3975

Hi Dan,

The MAX31855KASA+ chip doesn’t allow any grounded leads on the thermocouple. If you look at the MAX31855KASA library I wrote, you’ll notice that I would look for those error conditions to happen (shorted to grounded, shorted to VCC, and open). In the osPID main firmware, when these error are detected, the error will pop out. The MAX31855KASA+ chip uses a differential amplifier without grounding any of the thermocouple lead in order to measure below 0 Degree C.

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in reply to: Mods to control a fan with the second relay? #3969

John,

Your intention of using the fan is to circulate the air within the oven or to lower down the temperature (during cooling stage)?

I have personally tried this before. What I have notice is, during the stage preheat, soak, and reflow, the temperature on the target PCB climbs slower compared to that without the fan running. Only during cooling stage, the fan helps to basically cool the PCB faster (as long as it not faster than 6 C/s).
But, I also believe it depends very much on the volumetric size of the oven itself.

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in reply to: Bluetooth #3950

You definitely can use SoftSerial to communicate with the Bluetooth module preferably at lower baud rate (9600) to reduce the amount of interrupt that takes place.

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in reply to: Main board mounting holes… #3981

Hi John,

I’m using metric measurement rather than imperial, the holes are for M2 screws basically.
Yes, it is very tight but I will definitely move any traces close to those holes in the next revision.

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in reply to: Arduino Reflow Oven Controller Shield #3922

Hi,

I notice that it has to do with the wall adapter especially if it is noisy. It only happens with some of the customers’ unit.
Weirdly, Brett & I couldn’t produce the noise they experience both here in Malaysia and the States.

I think both capacitor & ferrite bead helps to eliminate/reduce the noise couple directly on the wires. But, we had to do something with the incoming power wire from the AC-DC adapter (shield it or move it). I guess that is the noise that magnetically coupled to the thermocouple wires.

Thank you for the suggestions.

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in reply to: Arduino Reflow Oven Controller Shield #3920

Hi,

We have a new prototype all ready and tested based on the new MAX31855KASA+ chip with a lot of other improvements.
But, if you look around, you might notice that we had some noise issue on this chip on the osPID Kit.
We are pulling our hair out because it only happens in certain places out there which we are unable to experience on our own.
So, we had to put this on hold at least for now.

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in reply to: Front-end and Thermocouple Input #3916

Scott,

The firmware reads thermocouple by default. On the front end, if you didn’t reconfigure them to read thermistor instead, it should not be doing so.
I’m trying to create your scenario here but I weren’t able to do so unfortunately. I ran a setup with a reflow oven shield running concurrently and varying set point(s) and both of the setup always shows comparable readings (2-3 Degree Celsius different) for over few hours. The osPID Kit is controlling the heater element through a SSR in this setup.

I note that there is no display in the UI of which input is being used

That is something that we might look to implement in the release.

Are you having any of the power cables or SSR wires overlap on the thermocouple?

After trying a lot of variation of setup, the only time I have fluctuating readings is when the thermocouple leads at the terminal block side are somehow touching or overlapping each other. Can you look into this as well just in case?

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in reply to: thermocouple calibration #3910

Dominic,

We are looking into that option and would probably do that in the next release of the firmware & front end.
At the same time, we want to hear more from everyone on their units.

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in reply to: thermocouple calibration #3909

Hi Tony,

The MAX31855 chip is being power off by an LDO (just like your approach) after a switcher. The last time I check it was around ~25mV for the switcher output.
I will measure again this week (someone took the scope).

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in reply to: thermocouple calibration #3907

Hi Dominic,

In the datasheet (page 11 Rev 2 latest from Maxim website), they recommend 10nF, but I also read some people using 100nF. It seems that this happens to a lot of other design even on simple breakout boards. If you look at their evaluation kit datasheet they also put a 10nF capacitor. On top of that a ferrite bead for each line (not sure whether it will affect the reading accuracy as it has some resistance).

I don’t think the twisted power leads makes any different (not differential signal). I’m using an old batch of wires. The one you are having, is the newer ones custom made for us by a connector company. But, you try.

I’m currently using the thermocouple bought from Adafruit (newer thinner ones and older thicker ones) and Lab Facility’s.

Please let us the outcome, we are eager to know.

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in reply to: thermocouple calibration #3906

Tony,

NPO capacitor supposed to perform better than X7R and the rest, across the whole temperature range. But, check the tolerance.

I swapped with as many AC-DC adapter I have here (switching based & transformer based) but I can’t get what you guys are seeing.
Do you guys have the part number of the thermocouple you guys are using?

[rocketscream]

in reply to: thermocouple calibration #3904

I tried adding a cap to one of the osPIDs with the terminal method and while the noise is less, the accuracy is still off. It’s reading negative temperatures and bouncing around, just not as quickly as before.

It didn’t work well with mine too as all my thermocouple leads are way too thin compared to the capacitor lead. So, it’s kinda loose on the terminal block.

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