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Netduino & Hottop
ginny
posts regarding Artisan roast control are:

http://forum.home...post_46047
 
RAG
SMICO, thanks for the info, expertise, and encouragement. Hope we hear more details about the forward air intake setup. Looks pretty good (like the stainless) as well with great insight into some of the problems of redesign.

I wonder about the fin enhancement design. Seems like you'd want perforated fins as well to reduce baking and hotspots. Haven't seen any real discussion of design on that mod as far as bean contact time, time in mass etc. Increase number of small fins vs. adding extensions. Trial and error for the truly obsessed seems the only avenue. Maybe there is some software that could analyze video of colored bean objects and determine an effective solution. Now that is crazy talk....

I logged my first roast today with bluetooth and I now have to hurry and design the control portion as I see room for vast improvement (unfortunately busy for next week). I had purchased the p model by mistake and now I need to add heat percentage vs. on off.

btw. The Artisan bluetooth connection was flaky (terminal session 100% vs. artisan drops erratic) until i reduced the sample interval to 4 sec. As a by product I changed my $5 bluetooth module to have the name of Hottop and changed com from 9600 to 19200 (seemed to have no effect but once less difference with tc4 default)
RAG attached the following image:
sulawesi.png
 
smico
RAG, this looks like very nice roast.
Longer and higher fins are not much discussed here from what I remeber, mostly because Ciel, our local HT mod expert did not implement that modification on his roasters. I hope that at some point he will, and that will be supported with calculations, heat transfer theory and precise measurement of all trials. I love when someone does work for me :)
There were several long discussions on HB, one is here: http://www.home-b...14069.html You can find some nicer implementations there.
I will do mine at some point.
Rama won 1st place on HB home roaster competition with that roaster. He would have won it without it, I am sure. Still, I like the modification.
Hottop B2 + HTC, Cremina 83, OE Pharos, Brewtus IIIR, Baratza Vario
 
RAG
So don't laugh but I installed insulation behind the firewall. This is insulation used in race cars with contact temp well above bean combustion. So I include pics.

I could clearly see the major problem when I got to installing this . Not only is the fan sucking everything into the elecltronics, motor, and plastic enclosure, it is a wide open channel from the bean shoot and chaff tray to the electronics when the bean shoot is open. The design uses a rather large slit instead of a rod and a feeble attempt at reducing the heat intake by adding a shield to the bean drop shoot. Now don't get me wrong, I love the Hottop. I especially love the great instructions on the Hottop web site for replacing any component. But this community is great, and I cant wait to do the 165 and exhaust mods from Ciel's excellent Mod articles to get the mechanics of this unit on the right path. Then it's back to my original intent to add pwm control to the heater and fan.
RAG attached the following images:
firewall2.jpg firewall1.jpg
 
RAG
Got distracted with the firewall Mod and the RAF. Now back to control.

Added the 165F override by Ciel. Put in a DPDT switch to the standard thermocouple that allows me to switch between default and reading the electronics area temp. The added benefit is the switch acts as a forced heater on switch. Obviously not a safe thing to do, but either is roasting.

So I took a look at the fan control. A 90us period (11.1khz) PWM with 15/50/75 duty cycle pulled low for on logic. Heater control was just switched low for on as well. Looks like you can safely just tap right into these lines for controlling the heater and fan. I'll of course verify that before I do, but I have a high level of certainty now.

I'm debating if I still want manual control or if Bluetooth is adequate. In any case, I definitely want default hottop automated control as well as my custom control.

So far so simple. I'm tempted to utilize some existing PID software but not sure there is a need with the nature of the Hottop roasting process. For now just setting up a low frequency ~.5 hz PWM for heater control seem like it would work. Any one care to comment?

Also looking for a part number for the two wire connector used for the fan and built-in thermocouple connectors if anybody knows that.

Thanks
 
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