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Date: 10 May 2007 11:13:40
From: Jim in NJ
Subject: Variac Control of Roaster Heating Coils
I was wondering if people have experience on how far heating coils on
consumer products can be pushed and to what effect.
For instance, when using a variac on a popcorn popper roaster, can
most work well at a 10-15-20% increase in volts or is there a high
failure rate above 10%.
Secondly, do internal electronics powersupplies have a lower tolerance
than heaters?

I'm also curious as to the temperature and or roast time effects with
these modest voltage changes; ie is there a 10% wattage change with a
10% voltage change or are the effects non-linear.
I'm just trying to set some boundries before starting my experiments.

Thanks in advance to the group.
Jim

Long time lurker, Rocky, Silvia, Aeropress, Z&D





 
Date: 10 May 2007 11:59:53
From: Jim
Subject: Re: Variac Control of Roaster Heating Coils
Jim in NJ wrote:

> I was wondering if people have experience on how far heating coils on
> consumer products can be pushed and to what effect.
> For instance, when using a variac on a popcorn popper roaster, can
> most work well at a 10-15-20% increase in volts or is there a high
> failure rate above 10%.

I'd suggest a variac on the FAN, not the heater. That's my plan. That
way, increase the fan, lower the temp. Decrease the fan, raise the
temp. A heavy duty variac is expensive. You can get one rated for the
motor for a fraction of the cost.

I'm on maybe my fourth or fifth Poppery II clone, and now searching for
an original Poppery. For one thing, the original has a 120VAC motor.
The second version has a low voltage DC motor. I do have some
transformers that I could use after a variac (variac > step down
transformer > DC motor with diodes in Poppery II clone), but given the
fact that I'm on my fourth or fifth Chinese Poppery II clone, I think
it's time to move up in quality. The original looks to be MUCH better
quality.

I've opened up the machines after failure, and even "repaired" a couple.
They seem to fail at the nichrome coil right at the rivet that is used
as a connection. I suspect that when riveted, the heater wire probably
gets malformed and narrowed at that point, so it burns out.


> Secondly, do internal electronics powersupplies have a lower tolerance
> than heaters?

That question just gave me a headache! Rephrase?

>
> I'm also curious as to the temperature and or roast time effects with
> these modest voltage changes; ie is there a 10% wattage change with a
> 10% voltage change or are the effects non-linear.

Realize that a 10% change in voltage will result in a greater change in
wattage. P = V^2 / R (wattage equals voltage squared divided by
resistance of the heater coil).






> I'm just trying to set some boundries before starting my experiments.
>
> Thanks in advance to the group.
> Jim
>
> Long time lurker, Rocky, Silvia, Aeropress, Z&D
>


  
Date: 10 May 2007 13:42:51
From: I->Ian
Subject: Re: Variac Control of Roaster Heating Coils
On Thu, 10 May 2007 11:59:53 -0700, Jim <askme@beforeyousend.com >
wrote:

>
>I'd suggest a variac on the FAN, not the heater. That's my plan. That
>way, increase the fan, lower the temp. Decrease the fan, raise the
>temp. A heavy duty variac is expensive. You can get one rated for the
>motor for a fraction of the cost.

I tried the fixed element and variable fan, but found it wanting.

A variac on the heater is a more controllable environment. The beans
move progressively more as they roast in a constant fan speed and it
is simple to increase the power to accomodate lower air resistance due
to greater spacing between the beans.

FWIW, I start at 90v and increase 1v / 15 sec to about 110v on my FR
sample roaster. I increased the fan stock speed by using a fixed
13.5VDC supply.


   
Date: 10 May 2007 18:11:14
From: Johnny
Subject: Re: Variac Control of Roaster Heating Coils

"I- >Ian" <someone@nowhere.com> wrote in message
news:uj0743dfoj2gkjvliik02qq5ntkqngs3pa@4ax.com...
> On Thu, 10 May 2007 11:59:53 -0700, Jim <askme@beforeyousend.com>
> wrote:
>
> >
> >I'd suggest a variac on the FAN, not the heater. That's my plan. That
> >way, increase the fan, lower the temp. Decrease the fan, raise the
> >temp. A heavy duty variac is expensive. You can get one rated for the
> >motor for a fraction of the cost.
>
> I tried the fixed element and variable fan, but found it wanting.
>
> A variac on the heater is a more controllable environment. The beans
> move progressively more as they roast in a constant fan speed and it
> is simple to increase the power to accomodate lower air resistance due
> to greater spacing between the beans.
>
> FWIW, I start at 90v and increase 1v / 15 sec to about 110v on my FR
> sample roaster. I increased the fan stock speed by using a fixed
> 13.5VDC supply.

I use both: variac on the heating coil and a lamp dimmer driving a small
autotransformer to control the 110 for the motor.




   
Date: 10 May 2007 14:01:39
From: Jim
Subject: Re: Variac Control of Roaster Heating Coils
I- >Ian wrote:

> On Thu, 10 May 2007 11:59:53 -0700, Jim <askme@beforeyousend.com>
> wrote:
>
>
>>I'd suggest a variac on the FAN, not the heater. That's my plan. That
>>way, increase the fan, lower the temp. Decrease the fan, raise the
>>temp. A heavy duty variac is expensive. You can get one rated for the
>>motor for a fraction of the cost.
>
>
> I tried the fixed element and variable fan, but found it wanting.
>
> A variac on the heater is a more controllable environment. The beans
> move progressively more as they roast in a constant fan speed and it
> is simple to increase the power to accomodate lower air resistance due
> to greater spacing between the beans.
>
> FWIW, I start at 90v and increase 1v / 15 sec to about 110v on my FR
> sample roaster. I increased the fan stock speed by using a fixed
> 13.5VDC supply.

Thanks for the comments. I'll take that into consideration. Maybe my
money *is* better spent on a bigger variac, instead of dropping over $50
on an original Poppery. My main hobby is tube guitar amps, and a second
variac could come in handy. The Poppery II clone seem to be in endless
supply at local second hand stores at $2 or $3 price point. It just
gets OLD having to replace and rewire every few months!

I made a triangle security tool out of a bolt, and I rewire so that the
switch works only the main heating coil. But I typically rock the
switch on and off between the very first crack I hear, through second
crack stage (not before first crack). How much time do you get between
first and second crack, with the increasing voltage method?

DISCLAIMER: You can burn your house down if you don't know what you're
doing!


    
Date: 10 May 2007 14:41:19
From: I->Ian
Subject: Re: Variac Control of Roaster Heating Coils
On Thu, 10 May 2007 14:01:39 -0700, Jim <askme@beforeyousend.com >
wrote:

>I->Ian wrote:
>
>> On Thu, 10 May 2007 11:59:53 -0700, Jim <askme@beforeyousend.com>
>> wrote:
>>
>>
>>>I'd suggest a variac on the FAN, not the heater. That's my plan. That
>>>way, increase the fan, lower the temp. Decrease the fan, raise the
>>>temp. A heavy duty variac is expensive. You can get one rated for the
>>>motor for a fraction of the cost.
>>
>>
>> I tried the fixed element and variable fan, but found it wanting.
>>
>> A variac on the heater is a more controllable environment. The beans
>> move progressively more as they roast in a constant fan speed and it
>> is simple to increase the power to accomodate lower air resistance due
>> to greater spacing between the beans.
>>
>> FWIW, I start at 90v and increase 1v / 15 sec to about 110v on my FR
>> sample roaster. I increased the fan stock speed by using a fixed
>> 13.5VDC supply.
>
>Thanks for the comments. I'll take that into consideration. Maybe my
>money *is* better spent on a bigger variac, instead of dropping over $50
>on an original Poppery. My main hobby is tube guitar amps, and a second
>variac could come in handy. The Poppery II clone seem to be in endless
>supply at local second hand stores at $2 or $3 price point. It just
>gets OLD having to replace and rewire every few months!
>
Wow $50 for an original Poppery. Perhaps the missus will reconsider
her "No bloody way!" ;-)

My FR is as grey as I am, going on 6 years. I don't use it too often,
but it shows no sign of fading anytime soon.

>I made a triangle security tool out of a bolt, and I rewire so that the
>switch works only the main heating coil.

If you want to be safe, use a relay to allow power to the element ONLY
while the fan is powered. Plastic puddles are very messy or so I'm
told.

> But I typically rock the
>switch on and off between the very first crack I hear, through second
>crack stage (not before first crack).

BTDT. Too much PITA and not repeatable.

> How much time do you get between
>first and second crack, with the increasing voltage method?
>

I aim for 1st [395F] @ ~7minutes. If I keep ramping up to 110, I hit
~435F around 10 minutes. If I drop to 102 from 105 at ~375F, I hit
~435F about 11 minutes.

I think I always roast 671g in the FR.

>DISCLAIMER: You can burn your house down if you don't know what you're
>doing!

I ALWAYS have a C rated fire extinguisher at the ready, 1 step back
and to the right so I can find it even if the place is full of smoke.


     
Date: 10 May 2007 15:57:09
From: Jim
Subject: Re: Variac Control of Roaster Heating Coils
I- >Ian wrote:

> On Thu, 10 May 2007 14:01:39 -0700, Jim <askme@beforeyousend.com>
> wrote:
>
>
>>I->Ian wrote:
>>
>>
>>>On Thu, 10 May 2007 11:59:53 -0700, Jim <askme@beforeyousend.com>
>>>wrote:
>>>
>>>
>>>
>>>>I'd suggest a variac on the FAN, not the heater. That's my plan. That
>>>>way, increase the fan, lower the temp. Decrease the fan, raise the
>>>>temp. A heavy duty variac is expensive. You can get one rated for the
>>>>motor for a fraction of the cost.
>>>
>>>
>>>I tried the fixed element and variable fan, but found it wanting.
>>>
>>>A variac on the heater is a more controllable environment. The beans
>>>move progressively more as they roast in a constant fan speed and it
>>>is simple to increase the power to accomodate lower air resistance due
>>>to greater spacing between the beans.
>>>
>>>FWIW, I start at 90v and increase 1v / 15 sec to about 110v on my FR
>>>sample roaster. I increased the fan stock speed by using a fixed
>>>13.5VDC supply.
>>
>>Thanks for the comments. I'll take that into consideration. Maybe my
>>money *is* better spent on a bigger variac, instead of dropping over $50
>>on an original Poppery. My main hobby is tube guitar amps, and a second
>>variac could come in handy. The Poppery II clone seem to be in endless
>>supply at local second hand stores at $2 or $3 price point. It just
>>gets OLD having to replace and rewire every few months!
>>
>
> Wow $50 for an original Poppery. Perhaps the missus will reconsider
> her "No bloody way!" ;-)
>
> My FR is as grey as I am, going on 6 years. I don't use it too often,
> but it shows no sign of fading anytime soon.
>
>
>>I made a triangle security tool out of a bolt, and I rewire so that the
>>switch works only the main heating coil.
>
>
> If you want to be safe, use a relay to allow power to the element ONLY
> while the fan is powered. Plastic puddles are very messy or so I'm
> told.

Mine is wired so the is ALWAYS on, as soon as you plug it in (along with
the voltage dropping coil). The switch controls the main heat coil on
and off, so I'm safe.


>
>
>> But I typically rock the
>>switch on and off between the very first crack I hear, through second
>>crack stage (not before first crack).
>
>
> BTDT. Too much PITA and not repeatable.

Since I sometimes get great tasting coffee, and sometime "just good," I
have to agree.


>
>
>>How much time do you get between
>>first and second crack, with the increasing voltage method?
>>
>
>
> I aim for 1st [395F] @ ~7minutes. If I keep ramping up to 110, I hit
> ~435F around 10 minutes. If I drop to 102 from 105 at ~375F, I hit
> ~435F about 11 minutes.
>
> I think I always roast 671g

I eyeball it, but I'll weigh next time. Since I'm using the same blend
all of the time, I figure eyeballing is fine (but maybe I'm wrong?).



> in the FR.

FR?

>
>
>>DISCLAIMER: You can burn your house down if you don't know what you're
>>doing!
>
>
> I ALWAYS have a C rated fire extinguisher at the ready, 1 step back
> and to the right so I can find it even if the place is full of smoke.


      
Date: 10 May 2007 17:43:24
From: I->Ian
Subject: Re: Variac Control of Roaster Heating Coils
On Thu, 10 May 2007 15:57:09 -0700, Jim <askme@beforeyousend.com >
wrote:

>I eyeball it, but I'll weigh next time. Since I'm using the same blend
>all of the time, I figure eyeballing is fine (but maybe I'm wrong?).

Easy to check : Eyeball a half dozen samples, then weigh them. If
they're within your tolerance, you're good to go.

Over the long run, a scale is probably better as there is less
temptation for "Yeah, that looks about right"

You may serendipitously make the best roast ever, but never be able to
repeat it. :-(


  
Date: 10 May 2007 12:05:28
From: Jim
Subject: Re: Variac Control of Roaster Heating Coils
DISCLAIMER for my previous message: Do NOT attempt any modifications
unless you understand what you are doing. You MUST wire it correctly,
and even then, you MUST attend to the popper at ALL times, at the risk
of burning down your house! All of this is experimental, proceed at
your own risk!

Jim wrote:

> Jim in NJ wrote:
>
>> I was wondering if people have experience on how far heating coils on
>> consumer products can be pushed and to what effect.
>> For instance, when using a variac on a popcorn popper roaster, can
>> most work well at a 10-15-20% increase in volts or is there a high
>> failure rate above 10%.
>
>
> I'd suggest a variac on the FAN, not the heater. That's my plan. That
> way, increase the fan, lower the temp. Decrease the fan, raise the
> temp. A heavy duty variac is expensive. You can get one rated for the
> motor for a fraction of the cost.
>
> I'm on maybe my fourth or fifth Poppery II clone, and now searching for
> an original Poppery. For one thing, the original has a 120VAC motor.
> The second version has a low voltage DC motor. I do have some
> transformers that I could use after a variac (variac > step down
> transformer > DC motor with diodes in Poppery II clone), but given the
> fact that I'm on my fourth or fifth Chinese Poppery II clone, I think
> it's time to move up in quality. The original looks to be MUCH better
> quality.
>
> I've opened up the machines after failure, and even "repaired" a couple.
> They seem to fail at the nichrome coil right at the rivet that is used
> as a connection. I suspect that when riveted, the heater wire probably
> gets malformed and narrowed at that point, so it burns out.
>
>
>> Secondly, do internal electronics powersupplies have a lower tolerance
>> than heaters?
>
>
> That question just gave me a headache! Rephrase?
>
>>
>> I'm also curious as to the temperature and or roast time effects with
>> these modest voltage changes; ie is there a 10% wattage change with a
>> 10% voltage change or are the effects non-linear.
>
>
> Realize that a 10% change in voltage will result in a greater change in
> wattage. P = V^2 / R (wattage equals voltage squared divided by
> resistance of the heater coil).
>
>
>
>
>
>
>> I'm just trying to set some boundries before starting my experiments.
>>
>> Thanks in advance to the group.
>> Jim
>>
>> Long time lurker, Rocky, Silvia, Aeropress, Z&D
>>


 
Date: 10 May 2007 18:34:56
From: hazzmat
Subject: Re: Variac Control of Roaster Heating Coils
On Thu, 10 May 2007 11:13:40 -0700, Jim in NJ wrote:

> I was wondering if people have experience on how far heating coils on
> consumer products can be pushed and to what effect. For instance, when
> using a variac on a popcorn popper roaster, can most work well at a
> 10-15-20% increase in volts or is there a high failure rate above 10%.
> Secondly, do internal electronics powersupplies have a lower tolerance
> than heaters?
>
> I'm also curious as to the temperature and or roast time effects with
> these modest voltage changes; ie is there a 10% wattage change with a
> 10% voltage change or are the effects non-linear. I'm just trying to set
> some boundries before starting my experiments.
>
> Thanks in advance to the group.
> Jim
>
> Long time lurker, Rocky, Silvia, Aeropress, Z&D

I would use the variac to turn volts down on popper, to slow the roast
down, or gain some control over roast curve. You could use the voltage
drop a variac can create to induce longer drying phase, then turn up power
back to normal (or beyond) to first crack then back down again to lengthen
development into second crack. The problem is that unless you have
"splitwired" the popper separating the fan powersupply from the heater(s)
powersupply, you turn the fan speed down as well as the heat output. The
need to keep beans moving and circulating puts a narrow limit on the range
of changes you can make to the heating curve. To split the wiring of the
popper you had better really know what you are doing or you can easily
blow up your popper/start house fire/electrocute yourself. Take care.

--
Get Big Brother out of my email to reply


  
Date: 10 May 2007 12:03:27
From: Jim
Subject: Re: Variac Control of Roaster Heating Coils
hazzmat wrote:

> On Thu, 10 May 2007 11:13:40 -0700, Jim in NJ wrote:
>
>
>>I was wondering if people have experience on how far heating coils on
>>consumer products can be pushed and to what effect. For instance, when
>>using a variac on a popcorn popper roaster, can most work well at a
>>10-15-20% increase in volts or is there a high failure rate above 10%.
>>Secondly, do internal electronics powersupplies have a lower tolerance
>>than heaters?
>>
>>I'm also curious as to the temperature and or roast time effects with
>>these modest voltage changes; ie is there a 10% wattage change with a
>>10% voltage change or are the effects non-linear. I'm just trying to set
>>some boundries before starting my experiments.
>>
>>Thanks in advance to the group.
>>Jim
>>
>>Long time lurker, Rocky, Silvia, Aeropress, Z&D
>
>
> I would use the variac to turn volts down on popper, to slow the roast
> down, or gain some control over roast curve. You could use the voltage
> drop a variac can create to induce longer drying phase, then turn up power
> back to normal (or beyond) to first crack then back down again to lengthen
> development into second crack. The problem is that unless you have
> "splitwired" the popper separating the fan powersupply from the heater(s)
> powersupply, you turn the fan speed down as well as the heat output.

...and without the isolated (splitwired) fan, you'll need a variac rated
for high enough current (probably 15A or better). They are EXPENSIVE.
With the isolated motor, you can get a lighter duty variac.


> The
> need to keep beans moving and circulating puts a narrow limit on the range
> of changes you can make to the heating curve.

But that can be varied by how many beans are in the popper. Less beans
move easier, more beans require more fan speed.

> To split the wiring of the
> popper you had better really know what you are doing or you can easily
> blow up your popper/start house fire/electrocute yourself. Take care.
>

YES, and I should've given a similar warning on my previous post. I'll
go back and respond to myself!