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HT Roaster Interface devices
smico
Top  #26 Print Post
Posted on 10/04/2012 12:49 AM
I have just finished roasting 5 back to back 250g roasts, and temperatures are in the same range, or a bit lower.
Hottop B2 + HTC, Cremina 83, OE Pharos, Brewtus IIIR, Baratza Vario
 
JimG
Top  #27 Print Post
Posted on 10/04/2012 8:18 AM

Quote

smico wrote:
Maximum temperature in the electronics area was 69C (157F).

How much higher would be safe to go? I am going to do few 250g back to back today.


I haven't checked the spec's for each and every component. Most of the IC's on the TC4 and TC4C boards are rated for at least 85C (for specified operation).

The LM358D op amp on the TC4C is rated at 70C. This is part of the system that automatically switches the power source away from USB when/if 7V or more is applied to the power jack.

I'm going to go out on a limb (because I have not looked at every component) and say the boards should be good for at least 70C, by spec.

Jim
 
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smico
Top  #28 Print Post
Posted on 10/04/2012 3:27 PM
So far so good, although I am not very comfortable running on the edge.
For regular one off HT roasts and full cooling cycle it's safe as temp reaches some 55C.
I will use my second TC4 after I manage to connect it to Nano or Mega, and capture temp graphs with Bourbone. At the end I will probably add insulation to the backwall. If that is not enough, small fan with external intake in the electronics area will help I am sure.

Thank you for your help Jim.

Miroslav
Hottop B2 + HTC, Cremina 83, OE Pharos, Brewtus IIIR, Baratza Vario
 
JimG
Top  #29 Print Post
Posted on 10/04/2012 3:47 PM
The op amp with the 70C rating will be present on most, if not all, Arduino boards. It's also used on the TC4C. But not present on the TC4 shield or any HTRI boards.

There could be other components that have similar 70C temp ratings, but a quick scan at the parts lists for the HTRI boards and TC4 shields didn't show anything rated below 85C.

I can provide you with the full BOM's if you want to do a detailed review.

Jim
 
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smico
Top  #30 Print Post
Posted on 10/04/2012 7:26 PM
No need for that Jim.
Back to back roasting is major feature for me and I will be doing it often. I will have to keep electronics cool somehow.
Thanks again for your help.
Miroslav
Hottop B2 + HTC, Cremina 83, OE Pharos, Brewtus IIIR, Baratza Vario
 
smico
Top  #31 Print Post
Posted on 10/14/2012 7:51 AM

Quote

smico wrote:

Jim,

Maximum temperature in the electronics area was 69C (157F).

How much higher would be safe to go? I am going to do few 250g back to back today.

Thanks,

Mirosalv

Dangerously high temperatures in the HT component area were reached because I was not using full 5 min cooling cycles between roasts. Also, my filter was not allowing much of the air flow.

Yesterday, I did 4 back to back 250g roasts with full cooling cycles and temperature reached 50C after second roast, and stayed between 48C and 51C almost all the time. Temperature would raise to 55C for a few minutes at the end of roasts.

I consider my last week's experiments as a proof that Hottop-Arduino-TC4-HTC can run up to 70C, but I will never do it again.

Still, I will keep an eye on temperatures in different areas of HT and post some graphs at some point in the future.

Regards,

Miroslav
Hottop B2 + HTC, Cremina 83, OE Pharos, Brewtus IIIR, Baratza Vario
 
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