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Topic: Baratza Virtuoso -- DC motor? (11 msgs / 358 lines)
1) From: Scott Marquardt
Is anyone with one of these grinders able to check the voltage across the
motor during operation for me?
I'm doing a farmer's market (roasting and brewing), and the other morning to
my horror I realized that my inverter -- which I use with my Maestro Plus --
was a couple hundred miles away in our other vehicle. I pre-ground my
brewing beans at home -- a hassle and actually messier at the market than
just grinding there using the inverter.
That's backstory. But I read yesterday that the Virtuoso uses a DC motor. If
that's so, and if it happens to be useful with 12V, it's a candidate for use
at the market, for sure. That'd spare me needing to use an inverter (since
the drum motor and cooler are 12V as well).
So if anyone with a meter is in a tinkering mood, I'd sure be glad of some
information about the hardware!
-- 
Scott

2) From: raymanowen
Scott, I'll go out on a bit of a limb here, because I have not actually had
a Baratza Virtuoso grinder apart, whereas I have had the Solis grinders
completely to pieces.
They're all 120v motors.
What would they do with the heat from the Nichrome ballast? They couldn't
use it. I've had a virtual DVM on the motor, and it gets full line power.
Guaranteed.
Want a 12 v grinder motor? Use a Kawasaki or Honda starter motor, and have a
20 - 30 amp source and wiring. Jumper cables from your car battery. Just
remember, when you run your battery down to 10.2 volts open circuit, it's
effectively discharged and will not start your engine.
Cheers -RayO, aka Opa!
-- 
"When the theme hits the bass, I dance the Jig!" - -Virgil Fox at the Mighty
Wichita (ex- NYC Paramount) WurliTzer- 1976

3) From: Scott Marquardt
10.2, eh? A good number to remember. I've often wondered if there was a good
benchmark of caution on that score. Thanks.
Yeah, a respondent at CG just mentioned that the DC is darned high on the
Virtuoso. A crying shame. I hate the notion of retrofitting someting alien
to the chassis of these grinders.
- Scott
On 8/6/06, raymanowen  wrote:
<Snip>

4) From: raymanowen
I found a highly educational
batteryinfo site,
and when you read
1.72v/cell open circuit(X6 cells), the internal resistance of the battery is
high enough to drop it all when you connect it to the starter motor.
And your interior dome light goes out.
The horn draws a lot of current- more than the headlights. Uneeda horse if
the dome light goes out when you hit the horn button.
You could wire a Schmitt trigger or op amp voltage comparator to turn on a
Red led when the battery voltage is too low.
In the winter cold, early sunset, creeping home in stop/slow traffic,
headlights and heater blower full tilt. Arrive home, park it, shut it off.
It could stay asleep for you in the morning.
Hmmm- "a respondent at CG just mentioned that the DC is darned high on the
Virtuoso." Where did he get that tidbit? An electric drill, vacuum cleaner,
router and Skill saw motor are all pretty powerful and don't use DC. It's
not necessary and would just add to the cost and complexity.
I don't know about the Baratza, but the specs are so similar to the Solis,
et al., that use no rectifier. It's a stretch.
Cheers -RayO, aka Opa!
On 8/6/06, Scott Marquardt  wrote:
<Snip>
-- 
"When the theme hits the bass, I dance the Jig!" - -Virgil Fox at the
Wichita WurliTzer

5) From: Scott Marquardt
The Virtuoso is marketed as possessing a DC motor. That's not what someone
checked for me -- that was the starting point for this question. Given that
it's a DC, I'm wishing it were in the neighborhood of 12V.    :-)
On 8/7/06, raymanowen  wrote:
<Snip>
-- 
Scott

6) From: Jim Mitchell
Scott -
I wonder if this might not be a case of Marketing Weasels talking across, 
rather than to, their market.
Specifically, the Barazata DOES have a DC - Direct Coupled - motor, which 
drives the burrs through a shaft, but the moter itself is an AC -Alternating 
Current - motor.
The whole 'Direct Coupling' with a low-speed AC motor, as opposed to using a 
higher-speed motor and gear reduction may be important to the Marketeers, 
but in reality both systems seem to work well for inexpensive light-duty 
grinders. Direct Coupled grinders like the Rocky are quieter, geared 
grinders like the Gaggia MDF, spin a little more slowly and have more 
torque.
In any case manufacturers like to brag about their drive systems, and 'DC' 
is a popular acronym.
Cheers
Jim

7) From: Scott Marquardt
Good thought -- though I don't think that's the case here since DC is
contrasted with AC. A google search that indicates this even in the
summaries:http://www.google.com/search?hl=en&lr=&q=baratza+virtuoso+%22dc+motor%22+acThis not being a case of that doesn't subtract at all from your caution
about marketeing weasels, of course.   ;-)
On 8/7/06, Jim Mitchell  wrote:
<Snip>

8) From: Jim Mitchell
This is a multi-part message in MIME format.
Indeed, the specifications are quite clear that the Virtuoso uses a =
high-speed DC motor with a reduction gear, which would make it pretty =
similar to the motor unit in the Gaggia MDF, which I believe is a =
gear-reduction AC motor.
I'm frankly puzzled as to why they decided to use a DC motor, since =
there is no provision for speed-control, which would be the DC motor's =
real advantage over an AC unit, and the DC motor will require an AC/DC =
conversion stage - perhaps it's now cheaper to use an IC-based converter =
than the typical large starting capacitor that many AC motors require - =
although the reduction gear should give ample starting torque.
Jim

9) From: Philip Keleshian
This is a multi-part message in MIME format.
I don't have Virtuoso but I did have a Solis.  The Solis has a universal
motor.  A universal motor is a series wound DC brush motor which has
been "tweaked" to work on AC.  They have been very popular in home
appliances for many years.  Since they are usually high speed motors
they yield more power for their size than true AC motors.  
 
Nowadays ceramic magnets and solid state rectifiers are cheap, so
permanent magnet field brush motors are popular.  They are like shunt
wound DC motors.  Shunt motors (and permanent magnet) motors have a
fairly constant speed with changing load while series motors have a very
load dependant speed.  
 
Some devices with heating elements use low voltage DC motors with some
or the entire heating element serving as a dropping resistor.  I would
think that if they are touting their DC motor, the implied virtue would
be constant speed.  The constant speed would be out the window if they
used the low voltage motor, dropping resistor approach.  More than
likely they are using a 120 volt DC motor fed with a bridge rectifier.
 
Phil
From: homeroast-admin
[mailto:homeroast-admin] On Behalf Of Scott
Marquardt
Sent: Sunday, August 06, 2006 3:09 PM
To: homeroast
Subject: +Baratza Virtuoso -- DC motor?
 
Is anyone with one of these grinders able to check the voltage across
the motor during operation for me? 
I'm doing a farmer's market (roasting and brewing), and the other
morning to my horror I realized that my inverter -- which I use with my
Maestro Plus -- was a couple hundred miles away in our other vehicle. I
pre-ground my brewing beans at home -- a hassle and actually messier at
the market than just grinding there using the inverter. 
That's backstory. But I read yesterday that the Virtuoso uses a DC
motor. If that's so, and if it happens to be useful with 12V, it's a
candidate for use at the market, for sure. That'd spare me needing to
use an inverter (since the drum motor and cooler are 12V as well). 
So if anyone with a meter is in a tinkering mood, I'd sure be glad of
some information about the hardware! 
-- 
Scott

10) From: Scott Marquardt
Geez. Well, that'd take a few D cells to power, since the car battery's
clearly not an option.   ;-)
On 8/7/06, Philip Keleshian  wrote:
<Snip>
-- 
Scott

11) From: Philip Keleshian
This is a multi-part message in MIME format.
About 80 1.5 v D cells should do it.
 
I was thinking. They are claiming a 500 RPM motor.  I tend to take
claims literally. That is going to have to be a massive motor.   Do they
mean burr speed?  
 
If the 500 RPM is burr speed and they are using a gearbox, then the
claim doesn't stretch credibility.
 
Phil
From: homeroast-admin
[mailto:homeroast-admin] On Behalf Of Scott
Marquardt
Sent: Monday, August 07, 2006 11:33 AM
To: homeroast
Subject: Re: +Baratza Virtuoso -- DC motor?
 
Geez. Well, that'd take a few D cells to power, since the car battery's
clearly not an option.   ;-)
On 8/7/06, Philip Keleshian  wrote: 
I don't have Virtuoso but I did have a Solis.  The Solis has a universal
motor.  A universal motor is a series wound DC brush motor which has
been "tweaked" to work on AC.  They have been very popular in home
appliances for many years.  Since they are usually high speed motors
they yield more power for their size than true AC motors.  
 
Nowadays ceramic magnets and solid state rectifiers are cheap, so
permanent magnet field brush motors are popular.  They are like shunt
wound DC motors.  Shunt motors (and permanent magnet) motors have a
fairly constant speed with changing load while series motors have a very
load dependant speed.  
 
Some devices with heating elements use low voltage DC motors with some
or the entire heating element serving as a dropping resistor.  I would
think that if they are touting their DC motor, the implied virtue would
be constant speed.  The constant speed would be out the window if they
used the low voltage motor, dropping resistor approach.  More than
likely they are using a 120 volt DC motor fed with a bridge rectifier. 
 
Phil
From: homeroast-admin
[mailto:homeroast-admin] On Behalf Of Scott
Marquardt
Sent: Sunday, August 06, 2006 3:09 PM
To: homeroast 
Subject: +Baratza Virtuoso -- DC motor? 
 
Is anyone with one of these grinders able to check the voltage across
the motor during operation for me? 
I'm doing a farmer's market (roasting and brewing), and the other
morning to my horror I realized that my inverter -- which I use with my
Maestro Plus -- was a couple hundred miles away in our other vehicle. I
pre-ground my brewing beans at home -- a hassle and actually messier at
the market than just grinding there using the inverter. 
That's backstory. But I read yesterday that the Virtuoso uses a DC
motor. If that's so, and if it happens to be useful with 12V, it's a
candidate for use at the market, for sure. That'd spare me needing to
use an inverter (since the drum motor and cooler are 12V as well). 
So if anyone with a meter is in a tinkering mood, I'd sure be glad of
some information about the hardware! 
-- 
Scott
-- 
Scott


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