[Homeroast] Using a Variac to control a GeneCafe

Mike Chester mchet at charter.net
Wed Aug 17 12:07:15 CDT 2011

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.


-----Original Message----- 
From: Ken Knott
Sent: Wednesday, August 17, 2011 8:30 AM
To: homeroast at lists.sweetmariascoffee.com
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 
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,
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