HomeRoast Digest


Topic: Using a Variac to control a GeneCafe (11 msgs / 289 lines)
1) From: Ken Knott
I have access to Variac's so I thought I might give them a shot to control my Gene CAfe.  I understand that power fluctuations at the outlet are common and can make a significant difference in controlling your roast profile's conistency.
So...  My Variac's can be set to 120V or 140V.  I imagine I would want to use 120V. 
Second questions.  From there, I can set my Variac from 0 to 100%.  As wall outlet are supposed to provide 120V, am I correct in that I would set it to 100% and then plug in the old GeneCafe?  I'd rather not fry my GeneCafe if possible...  :)
Thanks in advance,
Ken
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2) From: Bob Glasscock
Ken,
I have been roasting with a Gene Cafe for over a year now with fairly 
consistent results. Note, I did not say excellent...merely consistent. 
I am very appliance oriented, so my technique has been "pedal to the 
metal" and watch and listen. Are there ramping formulas that would help 
improve my roasts, and where can I find them?
  --
  Bob Glasscock
Greenville, AL
Quoting Ken Knott :
<Snip>
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3) From: Edward Bourgeois
If you set it on 120v 100% you will get the full line voltage. If your
variac doesn't have a meter you will need a Kill-A-Watt meter($20+-)
to plug into the variac output and the Gene into the KAW.  If your
line plus demand pulls your voltage down below 120v you will need to
set on 140v and adjust. up until you get to your desired voltage.  A
varic doesn't hold the voltage steady. Line or demand  fluctuations
will require adjustments along the roast. Be aware that the display on
a KAW meter will not light up when the voltage applied is below around
93 or so volts. Start low and adjust up and once you hit above that
your display will appear and continue til you get where you want.
On Wed, Aug 17, 2011 at 8:30 AM, Ken Knott  wrote:
<Snip>
l my Gene CAfe.  I understand that power fluctuations at the outlet are c=
ommon and can make a significant difference in controlling your roast profi=
le's conistency.
<Snip>
t to use 120V.
<Snip>
s wall outlet are supposed to provide 120V, am I correct in that I would se=
t it to 100% and then plug in the old GeneCafe?  I'd rather not fry my Ge=
neCafe if possible...  :)
<Snip>
mariascoffee.com
<Snip>
ee.com/gallery/main.php?g2_itemId=7820
<Snip>
-- =
Ed Bourgeois aka farmroast
Amherst MA.http://coffee-roasting.blogspot.com/Homeroast mailing list
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4) From: Edward Bourgeois
Be sure your variac is rated for enough amps watts for the Gene's rating.
On Wed, Aug 17, 2011 at 10:15 AM, Edward Bourgeois
 wrote:
<Snip>
ol my Gene CAfe.  I understand that power fluctuations at the outlet are =
common and can make a significant difference in controlling your roast prof=
ile's conistency.
<Snip>
nt to use 120V.
<Snip>
As wall outlet are supposed to provide 120V, am I correct in that I would s=
et it to 100% and then plug in the old GeneCafe?  I'd rather not fry my G=
eneCafe if possible...  :)
<Snip>
tmariascoffee.com
<Snip>
fee.com/gallery/main.php?g2_itemId=7820
<Snip>
-- =
Ed Bourgeois aka farmroast
Amherst MA.http://coffee-roasting.blogspot.com/Homeroast mailing list
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5) From: Mike Chester
A variac is not a voltage regulation device.  The output is simply a 
multiplier that can be set and the output varies with the input.  For 
example, if you have it set to 110% and have an input of 110v, the output 
will be 121v. (1.1 X 110) If the input voltage goes to 120v, the output will 
go to 132v.  (1.1 X 120)  Where the variac is useful, is where your typical 
line voltage is low, say 105v, you can boost it to about 118V which is a lot 
closer to the optimum voltage for your device.  It is also ideal to control 
the heat on a manually controlled roaster.
There are true voltage regulating devices, but one that would handle a 
roaster would be cost prohibitive for most home roasters.
Mike

6) From: Ken Knott
Hi Bob,
I'm no expert, but I did spend a bit of  time asking a lot of questons  when I got started.  The 'experts' of the time suggested the following ramp and I've generally used it ever since and I've been pretty happy.
Set temp to 300 and time to 30 to begin...
0-5 min 300  (this is to warm the beans and machine to an even temp)
5-9 min 451  (so at 5 min, adjust dial to 451)
9-11 min 462  (again, at 9 min adjust to 462)
11- to first crack 482  (11 min, adjust to 482)
Drop to 471 and when temp goes past to 462 drop to 462.  (In other words... when you change to 471, the thermostat will overshoot and fall below 462.  At that point, change it to 462.  IF you change it to 462 from the get-go it will overshoot too far and cool too much.)
Roast as much further as you like...
Generally I get to around first crack between 13-14 min...  2nd crack will show up between 18-19 min... 
This may seem long, but considering the first 5 min of warming up the beans to and equilibrium temp, is pretty normal.
Let me know what you think... I've been using this method for 4 years and very pleased...  I just vary the time i roast past first crack based on the bean.  I typically go solely based on Sweet Maria's recommendations...
Thanks and I'd love to hear how it works for you.  Again, I did not come up with this...  so I take no credit...  :)
Ken
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7) From: Gary Raabe
Ken;
I used a variac with the Gene in the past. I just wanted to tell you, if you don't have a Kill-A-Watt there is another way.
My variac has a "duplex" outlet on it meaning, I can plug two items into it. I use an inexpensive volt meter to monitor the voltage at the outlet of the variac. I made a simple cord for this purpose from an old lampcord I had cut off of something. It had the plug molded into one end. I just stopped by my local Radio Shack and picked up a pair of post connectors and installed them on the end of the wires. I plug the wire into one of the variac outlets and plug the post connectors into the volt meter and watch the voltage that way. You can get volt meters really cheap these days. I've seen digital ones for $5 or less.
Also, I don't know how true it is but I was told it's not good to boost the voltage too far. It's bad on the heating element. I always used 123 volts as my upper limit.
Happy Roasting!
Gary
 
From: esprcorn
To: homeroast
Date: Wed, 17 Aug 2011 08:30:38 -0400
Subject: [Homeroast] Using a Variac to control a GeneCafe
I have access to Variac's so I thought I might give them a shot to control my Gene CAfe. I understand that power fluctuations at the outlet are common and can make a significant difference in controlling your roast profile's conistency.
So... My Variac's can be set to 120V or 140V. I imagine I would want to use 120V. 
Second questions. From there, I can set my Variac from 0 to 100%. As wall outlet are supposed to provide 120V, am I correct in that I would set it to 100% and then plug in the old GeneCafe? I'd rather not fry my GeneCafe if possible... :)
Thanks in advance,
Ken
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8) From: Jeffrey Kelly
I appreciate your GC program advice.  I'll try it.  I have strayed away from the 300 F equilibration and can't remember why.  
Back on the Variac topic, where did you find yours and how $ ( if I may ask).  The other day my service was at 113 V and roast times were about 2 minutes extended, normal for me is 116 V.  Funny, the cup may have improved but the jury is still out! 
JD Kelly
On Aug 17, 2011, at 4:01 PM, Ken Knott  wrote:
<Snip>
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9) From: Dean
Ken,
If your Variacs are set up to boost as well as adjust, 100% would 
probably be around 140 v (they will boost upwards of 17% if they are 
wired right),  so l'd start at the dot (around 85% if it's like mine) 
and use a volt meter to confirm.  Not all Variacs are wired to boost, 
so using a volt meter is important for safely.
Heat is proportional to the square of voltage (current) so boost 
conservatively!!  A 5% boost (6 volts) will give you 10% more power 
and probably reduce the heater life by as much as 20-25%, and motor 
life as well
Kill-a-Watt is a nice gadget to check voltage & power under load--I 
wish mine hadn't gotten damaged.
Have fun experimenting!
Dean
Too cheap to replace a broken toy in da weeds......
On 8/17/2011 7:30 AM, Ken Knott wrote:
<Snip>
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10) From: Phil Palmintere
Resurrecting the GC thread...
On my GC, I try to use a similar roast profile to the one you describe
below.  
However, my roasts (225g batch) don't achieve the target reported temp
during the allotted time. 
So, in your example, you have it set at 451 for minutes 5 through 9, at
which point you raise it to 462.  Does your GC report that the bean mass has
achieved 451 by the time you bump it up to 462???  Mine doesn't - not even
close. Ditto for minutes 9 through 11: you have it set to 462 -- does your
bean mass hit 462 prior to you bumping the temp to 482?
I've wondered about the way the thermostat controlled heater works.  Is it
either "on or off" (sort of digital) or does the heat generated actually
differ at differing settings (sort of analog).
Thanks
Phil
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11) From: John A C Despres
The Gene Cafe heater is either on or off, hence the five degree
fluctuations. It switches on or off depending on what your setting is
calling for.
There's another Gene Cafe roaster her in Grand Rapids who has wired his
variac directly to his heating element and it seems to work fine for him.
And his coffee tastes just fine.
As to profiles, play around, make small changes, keep notes, taste and make
more notes.
John
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