HomeRoast Digest


Topic: Rosto fan transformer/potentiometer update (14 msgs / 307 lines)
1) From: R.N.Kyle
Just send it to me:O) Play all you want, I understand, and will be glad =
to take the excess off your hands. I always know that MIKE MCCOFFEE'S =
roast are going to be good.
I'm allay willing to help a fellow list member out:O)
Ron Kyle
Anderson SC
rnkyle

2) From: Mike McGinness
I had it all assembled and wired together in three gang box. Grounded double
outlet bottom, Radio Shack 12v 3A transformer boost wired middle, Lutron 5A
fully variable fan control top. Plugged it in with dmm leads in socket,
turned on the fan control. Read 132v, no matter where the dial! Ok, strange.
Not a normal potentiometer in my limited experience. Turned it off, plugged
in the Rosto fan line. Turned on the fan control, now read 126v top and
varied smoothly down to around 75v. Hmmm. Boosted the fan but not as much as
I'd hoped.
Phase two. Pull out the transformer. Run down to Radio Shack and get the 24v
2A transformer (same price:-). Wired it in. Now tests 146v no load, 139v fan
load max. Now we're talking! During the summer hot months I was running
130v+ during start of cooling so this will work perfectly, for first of
roast heavy greens movement and cooling. Me thinks I'm going to like this.
Phase three will be tearing it all apart and rebuilding in a single control
box with heater control variac. No rush, all 100% functional now!
My only complaint is I roasted three 1/3# batches this morning and 4
yesterday. Don't need to roast. And I want to play! Hmmm, who can I give
some roasts to:-)
MM;-) aka Kona Konnaisseur miKe mcKoffee
Variac Rockin' Rosto Roasting
Rocky grindin' - Miss Silvia brewin'
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3) From: Randy Roy
Mike, Sounds great!!  The 12v boost is working for me now, but may not be
enough during the hot summer months when A/C use is heavy.  Voltage drops by
as much as 10v at times.  Right now I have 120-121v at the house outlet,
134v with the transformer (no load).  A 24v trans may be in my future.
Randy

4) From: AlChemist John
Sometime around 21:19 1/10/03, Mike McGinness typed:
<Snip>
Hand raised.  My SM order has not arrived and I am under 1 lb of green coffee.
(mostly joking about sending roasted beans, not about being low :-(
--
John Nanci 
AlChemist at large
Roasting and Blending by Gestalt
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5) From: dewardh
Mike:
<Snip>
yesterday. Don't need to roast. And I want to play!
That's *exactly* what limits my experimenting . . . what to do with all the 
darned coffee .  I almost wish for "failures" so I can chuck it and try 
again . . .
Deward
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6) From: Mike McGinness
From: "Randy Roy" 
<Snip>
by
<Snip>
As Ken mentioned he used the router controller and didn't get near top
voltage at it's highest setting. (no transformer I believe, just attenuating
line voltage) I suspect the fan controller is designed similarly since no
load and load max voltages are hugely different for me. Since you're using a
standard dimmer, which behaves like a standard potentiometer I believe, your
usable voltage with the 12v transformer sounded higher than mine. But with
the 24v transformer I'm getting max usable 139v to fan so that's more than
kick butt enough!
MM;-) aka Kona Konnaisseur miKe mcKoffee
Dual Variable Transformer Rosto Roasting
Rocky grindin' - Miss Silvia brewin'
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7) From: dewardh
Mike:
<Snip>
voltage at it's highest setting.
There's something "wrong" here . . . although I don't have one (yet) I've seen 
one used with a router , and it *did not* have that problem . . . it worked 
fine up to (almost) full speed.
<Snip>
load and load max voltages are hugely different for me.
These things are *not* potentiometers (variable resistors) . . . they work by 
switching the power on progressively later in the cycle (each half cycle).  A 
peak reading voltmeter will not properly display what they are doing.
<Snip>
standard dimmer, which behaves like a standard potentiometer I believe
A "standard" dimmer is *not* a potentiometer, and *does not* behave like one. 
 It does the same thing a motor controller does, only with lower ratings and 
without some of the protective circuitry that a motor controller (hopefully) 
has, since they're intended only for resistive loads (dimmers, that is).
The "half power" behavior that Ken reports strongly suggests that half the 
triac (the control element in the device) was burned out, probably as a result 
of overload.  The result would be power reaching the load only on alternate 
half cycles . . . consistent with the performance described.
The site below offers a description of how dimmers work, and discusses some of 
the problems associated with them.  Note the repeated references to heat and 
heat sinks  . . . the things have the same internal components as SSRs, and 
thus the same problems with heat.http://www.passandseymour.com/knowhowfaq/showquestions.cfm?faqcategory=Dimme 
rs%20and%20Controls
Deward
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8) From: Mike McGinness
Regardless the correct terminology or how it works the 'Lutron 5A fully
variable ceiling fan controller' I'm using does not yield 100% of input
voltage. A controlled router almost at full speed is hugely different than a
home roasting appliance fan "almost" at full speed IMO! What appears
negligible (say 10 to 20%) drop in voltage would/could greatly reduce bean
movement on a design barely making it as it is. Hence this type of
controller applied to line voltage only may not be the way to go. Which is
really mute. Paired with the $10 Radio Shack 25.2v 2A transformer (pn
273-15128) it kicks butt giving about 17% usable boost, load 139v.  So for
$9.94 for fan controller, $9.99 for transformer, $0.41 for dual socket you
get great smooth boosted AC fan control.
MM;-) aka Kona Konnaisseur miKe mcKoffee
Dual Variable Transformer Rosto Roasting
Rocky grindin' - Miss Silvia brewin'
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9) From: Mike McGinness
From: "dewardh" 
<Snip>
the
<Snip>
It is bizarre but I know what you mean. And it's not a cost issue. Using an
inexpensive yet high quality bean from Tom for experimenting makes it only
about $1.50 to $2 per 1/3# batch including s/h! But it's the principle of
letting good coffee go to waste. Just seems a crime against Nature
somehow:-)
MM;-) aka Kona Konnaisseur miKe mcKoffee
Dual Variable Transformer Rosto Roasting
Rocky grindin' - Miss Silvia brewin'
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10) From: Tom Gramila
On Sat, 11 Jan 2003, dewardh wrote:
<Snip>
	Thanks for the lead on still more good info!!
	With all this talk of boosting fan voltages, I think I may try to 
push my WBI fan to see if I can run 180 rather than my usual 120 grams....
		
			Tom
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11) From: Ed Needham
Just for the heck of it...
I'm wondering if my old Melitta Aromaroast could benefit from hooking it up
to my variac and pumping up the voltage to both the fan and the heater.  Both
are anemic as designed.  The actual roaster is a good design (air baffle,
great chaff collector) for roasting beans but the fan and heater are just too
weak.
Ed Needhamhttp://www.homeroaster.comed
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12) From: Ken Mary
<Snip>
You may also want to replace the old rectifier board with a new bridge
rectifier as I did. It significantly boosted fan speed.
--
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13) From: Ed Needham
I remember you saying that, but didn't keep the post.  Is that a Radio Shack
part?  Do you have a part number?
Thanks
Ed Needhamhttp://www.homeroaster.comed
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14) From: Ken Mary
<Snip>
Any of their bridge rectifiers with ratings of 4 amps 50 volts or higher
will work, they are less than $3.00.
--
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