Arduino code not giving target temperature.

The last digit of the part no is the current rating, last 2 digits if its not a letter preceding it

Boardburner2:
The last digit of the part no is the current rating, last 2 digits if its not a letter preceding it

So EZ240D5 is 5amps. I presume that is OK

Thanks

Should be fine for 2 elements.
I do not find a need for the bottom elements to be on with my current oven.

dalpets:
I don't understand the question, Tom. Could you please clarify in circuit wiring terms for a noob.

Tom is in aus and may have gone to bed, so.

With IC's its common practice to have a DECOUPLING capacitor of 0.1 to 1 uF across +V and ground located as close to the chip as possible, this bypasses any noise signals that may interfere with operation of the IC.

One on the output helps the same way although there is another relationship with sampling frequency of the ADC which can cause under reading.

That one can be much smaller, nanofarads i would suggest.

dalpets:
So EZ240D5 is 5amps. I presume that is OK
Thanks

You only need worry if you power all 4 elements at once with the relay. (I didn’t realise there were four, or that they didn’t all always come on together.)
I had a look at the Sunbeam BT2600 online last night. The comments mentioned that the switch setting determines which elements are on.

Incidentally, the way I knew the relay is 5A…it’s written on it. :wink:
(Your pic showed it clearly.)
4 relay connections.jpg

Boardburner2:
Tom is in aus and may have gone to bed, so.

Actually, dalpets is in Oz too, I believe. Hence the 240V Sunbeam toaster oven and this:-
641a2ccff833dd9e88c89dd443adb8373f8a681b.jpg
And so am I. :slight_smile:

Boardburner2:
Should be fine for 2 elements.
I do not find a need for the bottom elements to be on with my current oven.

Tom is in aus and may have gone to bed, so.

With IC's its common practice to have a DECOUPLING capacitor of 0.1 to 1 uF across +V and ground located as close to the chip as possible, this bypasses any noise signals that may interfere with operation of the IC.

One on the output helps the same way although there is another relationship with sampling frequency of the ADC which can cause under reading.

That one can be much smaller, nanofarads i would suggest.

In my case that would be the 100pF polarised ceramic capacitor on the therm amp, would it not (see my early sketch)?

Boardburner2:
Another thought has occoured.

Say you have blink 1 second on to 1 second off.
Eventually a point is reached (equilibrium) beyond which temp cannot increase.

To cure that the mark to space ratio of the blink needs to be changed.

Ie more on less off.

If at 206 the light continues to blink i suspect this or a faulty thermostat.

If the light stops blinking then that would imply measurement problem.

When the oven is on the top light (L) goes solid amber. The middle light Tx continues to blink, the bottom light does not come on at all.

Tested the oven with thermometer & thermocouple, together taped on a scrap board & they both terminated @ 206C. However, there were a number of concerning temperature anomalies as between the serial monitor & the thermometer, on the rise to 206C eg., SM 142, T 128. Same on the fall.

I will test when the elements turn on v knob settings tonight.

dalpets:
When the oven is on the top light (L) goes solid amber. The middle light Tx continues to blink, the bottom light does not come on at all.

This would indicate that tom was correct and the ssr is shutting down.
Why the amber light stays on solid though baffles me.

dalpets:
Tested the oven with thermometer & thermocouple, together taped on a scrap board & they both terminated @ 206C. However, there were a number of concerning temperature anomalies as between the serial monitor & the thermometer, on the rise to 206C eg., SM 142, T 128. Same on the fall.

There will be some variance between the two if they have different thermal masses but that is excessive i think.

Have you done a calibration curve test.
Not mentioned in the link but i am assuming it was there origionally.

dalpets:
In my case that would be the 100pF polarised ceramic capacitor on the therm amp, would it not (see my early sketch)?

Yes should be a much higher value though 100nF to 1000nF.

Not shown in the data sheet though which is a bit unusual.

OldSteve:
Incidentally, the way I knew the relay is 5A........it's written on it. :wink:

Actually, dalpets is in Oz too, I believe.

I was not sure if that was a 3 or a 5 , they make both.

I thought he was burning the midnight oil, not sure which side he is on though.
3 or 4 hours difference ?

Sunbeam toasters were available in the uk at one time not sure if they still are.

Well I've run some temp tests & the results are as follows;

240C knob setting @ 288sec serial monitor max =216C: thermometer 210C

grill @ 287sec SM max=210C: T=207C

toast @ 320sec SM max=207:T=199C

  • SM= serial monitor
  • T= thermometer (0.5C accuracy in this range)

In all 3 case only the top 2 elements turn on.

Where can we go from here?. Any suggestions for some practical things I can try?
As a last resort I could try a different oven, but I don't see any in Australia that might fit the bill, particularly one that is spec'd for 225C+.

Incidentally there was an error in my circuit sketch that has already been picked up.
HREF should read GROUND.
Ground should read PIN13 (+). (Only the sketch was in error).

Thanks for any further help.

Boardburner2:
This would indicate that tom was correct and the ssr is shutting down.
Why the amber light stays on solid though baffles me.

There will be some variance between the two if they have different thermal masses but that is excessive i think.

Have you done a calibration curve test.
Not mentioned in the link but i am assuming it was there origionally.
Yes should be a much higher value though 100nF to 1000nF.

Not shown in the data sheet though which is a bit unusual.

I got that from a link for the therm amplifier on the REPRAP oven wiki page. As I said the company has ceased to operate & they have killed the link now. Would the capacitance value in any way relate to my problem? I seem to remember that it was there to suppress noise.
How do I do a calibration curve test. What does it calibrate?

Boardburner2:
This would indicate that tom was correct and the ssr is shutting down.
Why the amber light stays on solid though baffles me.

What do your lights do on heating?

Boardburner2:
I was not sure if that was a 3 or a 5 , they make both.

I thought he was burning the midnight oil, not sure which side he is on though.
3 or 4 hours difference ?

I am +9 1/2 (South Australia)

dalpets:
What do your lights do on heating?

arduino led , power light and amber light all blink in unison up to the set point then stop

Amber light no longer works now though as i took out the thermostat.

dalpets:
In all 3 case only the top 2 elements turn on.

That is very strange , is there a separate switch for the bottom elements ?

Used as normal off the mains at full belt,-
Can you see in each of the three position which elements heat up ?

Link to the manual perhaps ?

dalpets:
Would the capacitance value in any way relate to my problem? I

Doubtful but 0.1 uF would be a better choice.

I would trust the analog devices chip more than a multimeter for accuracy.
That's another complex discussion though.
Lets try to get the circuit sorted first.

Apologies for the many posts, i use a tablet normally and its only possible to do a concise post from a PC.

Boardburner2:
Doubtful but 0.1 uF would be a better choice.

I would trust the analog devices chip more than a multimeter for accuracy.
That's another complex discussion though.
Lets try to get the circuit sorted first.

Apologies for the many posts, i use a tablet normally and its only possible to do a concise post from a PC.

Don't forget there are 2 versions of the AD595-the A & C versions. The former has an accuracy of 2/3C whereas the latter is less than 1C. Currently I have the A version. I'll be changing that when I receive the C version.

Cutting to the chase, it seems that from all that's been said here that the relay is the most likely culprit.

Does anyone have a recommendation for a quality brand relay to try as a substitute?

After I have ruled out the relay it may be then time to try another oven.

crydom are a good make just need a bigger one.

Have you tried upping the target temperature in the software.?

Boardburner2:
That is very strange , is there a separate switch for the bottom elements ?

Used as normal off the mains at full belt,-
Can you see in each of the three position which elements heat up ?

Link to the manual perhaps ?

There is no switch.

I can't remember which of the 3 setting I was on but it maxed out at 275C, directly off the mains. That temp scorched the thermocouple. Had to change thermocouples after. Was getting strange readings. I'm loathe to try it again for that reason.

I was not clear, thermocouple is not needed.

On my oven the bottom elements only come on in the oven position.

In the toast /grill position only the top.

Not sure what the difference is but, i am trying to discover what position of the switch gives only the top elements on.

In this case your existing 'relay' should be sufficient.

What i am suggesting is try each position and see which elements 'glow'.
It is possible in the oven position that they will not however.

A smartphone camera however may be able to see the difference.

Have you monitored the ac voltage at the oven?