Joseph, I modded my new-to-me Poppery II using your helpful instructions and roasted about a pound of coffee with it yesterday. The only thing I did differently was to just plug the cord from the heating coils directly into the router controller. I couldn't see making a new connection when the original cord from the popper was still good. I love the new level of control I have with this setup! Thanks for taking the time to help out an electrically challenged individual like me, lol!
Hi Joseph, I finally analyzed the circuit and tested the AC supplied to the diode bridge from the parallel inner coil: 20VAC goes to the motor under load (this wire is black on my Presto PopLite unit. Red is the hot wire. So before making the connections, each person should check and not depend upon wire colors :). So given that the resistance of the inner coil is 50 ohms, with a total voltage drop over this coil and the motor under load in series of 120VAC, the equivalent resistance of the motor is 12.5 ohms and the motor draw is 1.6 amps. So your selection of a 2 amp 24VAC transformer for the motor is perfect. Not isolating the inner coil from the fan would yield 100 watts (50V X 2A[100V/50ohm]) of coil heating whenever the fan runs, reducing the in-situ cooling efficiency, so your solution of running them in parallel produces 1550 watts of heat in my unit (the large coil is 11.4 ohms and in parallel they are about 9.3 ohms, 12.9A X 120VAC), and allows for room temperature air during cooling. Thanks once again for presenting your design and wiring. I will be working on it today and can't wait to try it out!
ChicagoJohn Lesson #1 Learned: Don't turn the fan speed down a lot with coil voltage high! The air flow is needed to remove heat from the coils. In making a trial batch (popcorn), I lost heating. Cause - blown aluminum fuse (> 240C). Lesson #2 Learned: Don't get frustrated if #1 happens, stop thinking, and "test" it by unplugging the fan from your 20VAC transformer and plugging it back into a 120VAC receptacle! Motor dead - coil smoked! So with another brand new popper to be delivered today (and a spare heating assembly now wired to bypass all temperature controls -- perhaps to be used at a later date), I'll be trying again later today and tomorrow. This time, I plan to first chart curves of equilibrium roast temperature versus rheostat setting (at FULL 20VAC FAN SPEED) with no bean load, 25 gm green beans, 50 gm beans, and 100 gm beans, using whatever stirring or tilting I'd use in an actual roast (increasing the bean load will likely reduce airflow and increase equilibrium temperature.) After completing this exercise, I hope to have a better understanding of how to balance air and heat during roasting and avoid another high temperature scenario.
ChicagoJohn An improvement, then success. The new Presto PopLite fitted to the proper rewiring (including high temperature shutoffs), I was not satisfied with the mixing of the green beans without stirring. The following fixed that: I bought an aluminum funnel at Ace Hardware ($3). It has a wide end diameter of 12 cm (~4.75 in). I cut a section of that such that the small end diameter was just over 3 cm and the large end around 7.4 cm. At the large end, I left four "tabs" of about 12mm length and width and I bent these back to fit the popper cylinder. I positioned this cone perfectly within the cylinder/blower entrance piece and then pop-riveted it in place using the tabs. This increases the angle above the angle of repose of the beans and I was able to do the roast with 100 gm of beans without stirring, running the motor at 24VAC input (note that this is only part way to the maximum voltage of the dimmer switch output!). I decided to shoot for a 20 minute roast of Guatemala Atitian San Jeronimo Miramar, and I must say, that in terms of color uniformity it came out virtually perfect with just one or two shakes and no stirring, at just into 2nd crack. If you have a popper that uses the bottom air supply instead of the circumference swirl, (such as the Presto PopLite I have) you may want to try installing this funnel shape just above the air inlet.
Joseph Collins The following should link to an image on my Flickr account flic.kr/p/u7up2L and if you look in the lower right corner you will see an arrow above a horizontal line. Click on this and you should be able to download the image in whatever size you like. In addition, I'd be happy to e-mail you any other images you'd like that can be used as you wish without attribution. The only significant change I made to your modification would apply to poppers that have hot air introduced from a central port in the bottom (such as Presto PopLite), not for poppers that circulate air from ports around the circumference. E-mail Chicago.john@hotmail.com Thanks again, Joseph, for your outstanding videos without which I would have had a much steeper learning curve!
Hey Joseph! Cheers for this video, I just have a question. Do you reckon it’s possible to use ONLY the ‘router speed control’ as an alternative to your original mod? (So heating to the full/off/variable switch & fan to the dimmer looking dial)
Not exactly. The biggest thing is you don’t want the fan to get more than 24 volts. You might be able to just run the fan off of batteries to the dimmer switch and only use the AC power for the element. If you did this, you could desolder the diodes on the fan and wire the fan directly to make it slightly more efficient. If you wired 4 6v lantern batteries in series you’d get 24volts, run that through your dimmer and just run the heating coil on AC.
Hey Joseph, really helpful video man Thanks for sharing! :) I have a question though; would this same mod and wiring be compatible with a West Bend Air crazy II as well? It's the only popper that I have at home. Thanks again!
Thanks for posting. Looks great. So what are the voltages of the element and motor? I would like to check the switched and variable controller I'm planning on using will be suitable and be able to handle it. ChicagoJohn mentioned: Motor = 20V ac Element total = 120V ac Is this correct and what the switch and controller should be rated for? Why is there two individual elements? Is one thermostat controlled ?
+CakeCoffeeCafes The stats Chicago John mentioned were from his PopLite unit. I believe the motors are usually between 20 - 25 volts for various popper models. Pay attention to the current (amperage) also, because the total watts is the number you want to look out for. Remember the equation P = V x I. The power(P) in watts is equal to the voltage(V) in volts times the current(I) in amps. I installed a 2 amp 24VAC transformer for the fan, so that is 48 watts. Therefore a simple Light Dimmer switch that can handle up to 100 watts is perfect. The dimmer switch can handle the 120VAC because thats what a lightbulb operates on, however a 100W lightbulb only draws about 833 milli-amps. However, the heating element draws the full 120VAC at about 13 amps so its around 1,560 watts which is far too much for a simple dimmer switch, that is why I used the router speed controller. My unit does not have two elements, It only has one element, and there was no thermostat. The only thing the it has is a safety shutoff mechanism that is triggered by expansion of a small sliver of metal that disconnects the circuit when the heat causes it to expand. Some people have chosen to bypass this safety mechanism. I have had no need to do so.
Not much difference at all. You will still need the transformer because it basically does the job that the heating element did before you separated it. Therefore, the only difference would be to install a simple switch instead of a dimmer switch. You have to have the transformer because otherwise you will be sending ~115V directly to a 20v fan. The transformer steps the voltage down to 25v, which the fan can tolerate.
+Joseph Collins oh okay so I might as well install the dimmer too you are right! I might also install a different motor for the fan. I am thinking I found a weak dremel tool at harbor freight that might be a little more powerful that the fan in there.
+Joseph Collins I connected my fan to a 24 volt transformer for a computer and it died shortly. I think it worked well but it probably got too hot or something...
Yes, I originally purchased mine from radio shack. The part number is 273-1512 (25.2V Center tap 2.0A). However, radio shack might not sell this anymore, which would be unfortunate. I also found an equivalent of the radio shack transformer on mouser.com www.mouser.com/ProductDetail/Triad-Magnetics/F41X/?qs=sGAEpiMZZMvwUzoUXIIvycT6np3HRZBQxmjkESKdeMA%3d
+Joseph Collins good thinking. Would I just clip of the diodes since those convert the AC into DC and since the transformer is giving off DC, I don't need them or should I just leave them?
Either way is fine, but clipping them is more work and shouldn't be necessary. If you clip the diodes, you have to re-solder the connection. The diodes will create a minor voltage drop, so clipping them will be slightly more efficient, but I don't think it will make any significant difference.
This IS that video. If you look at the drawing, it is showing the inside of my box. My mod is very similar to the link here www.engadget.com/2006/02/28/how-to-make-a-popcorn-popper-coffee-roaster/ the only difference is that I added the rheostat. The rheostat is a Router Speed Controller from Harbor Freight.
Joseph Collins Thanks. I noticed that you use a switch as an on/off for the heating section. My router speed control has a rocker switch with an "off" position, so I assume I could eliminate the separate on/off switch. Have you found there is an advantage to having the separate switch?
The only reason I have a separate switch is because the router speed controller was added after my original mod. So yes you could essentially skip that switch and just use the one on the router controller.
What temperatures are you reaching with this mod? This is what I have done as well and I reach just under 400° when I roast, even when I slow the fan down. I want to get up to 420°, but am not sure what to do in order to achieve such a temperature.
+Eric Busby I can definitely get 420°. If you have done exactly as I have done and you are not reaching that temp, then I would suggest adding more beans. More beans in the popper seems to trap more heat inside. You can watch the video of me roasting at this link: ruclips.net/video/jV7tZmNEjQQ/видео.html&feature=iv&src_vid=S4KXvGZOivA&annotation_id=annotation_1779959155 You will see that I reach 220°C (428°F) near the end.
+Joseph Collins Adding more beans is what I have done, but when I have more than 100 grams the bed does not circulate well, or at all, without consistent/constant intervention on my part. At least, until the beans begin to yellow/tan. That is also with the fan speed at a constant and at its highest capacity for about 6 minutes (and up to 350° temperatures on my hands around that time). Even then, at the end of the roast, the beans generally don't reach any higher than 410° with 100-105 grams of coffee in the chamber. My last roasts were 96 grams and they have performed reasonably well, though I would like a tad more development without baking the beans. The temperature did not exceed 397°, but the nutty and underdeveloped flavors of my roasts have diminished significantly because I have been keen on measuring temperature and plotting development. I want to tease out more floral and delicate notes which I would think could only result from better development.
+Eric Busby The other thing I did in my mod which might help with movement. I drilled LOTS of holes all over the case in order to allow more air inside. I also used a screwdriver to make each vent in the chamber slightly larger... not too much because otherwise the beans will get stuck. It also could be something slightly different with your heating element as opposed to mine. The only other recommendation I can think of is try to get ahold of one of the 1500 Watt Poppery I's. The one I am using in this mod is a 1200 watt. The extra 300 watts might be just enough to get you that last bit you are looking for.
+Joseph Collins, I would have thought that drilling holes would be ineffective for retention of heat, so that is very curious to me. I will look at expanding the holes of the roaster chimney, though. Also, what is the reading for temperature what you charge at? Does the temperature before you introduce the beans reach 400+°?
+Eric Busby, I preheat the chamber to about 270 degrees before adding the beans. The holes in the case don't affect the temperature of the chamber. However, the increase in airflow does affect the temperature. The other important mod is the chamber extension. One thing you could try, is instead of using a can like I used, try finding a tempered glass chimney from an old fashioned oil lamp. The longer the chamber is, the better the heat retention and the glass allows you to see your beans even though its very long. You can buy the chimneys on HomeDepot.com
Joseph, I modded my new-to-me Poppery II using your helpful instructions and roasted about a pound of coffee with it yesterday. The only thing I did differently was to just plug the cord from the heating coils directly into the router controller. I couldn't see making a new connection when the original cord from the popper was still good. I love the new level of control I have with this setup! Thanks for taking the time to help out an electrically challenged individual like me, lol!
Hi Joseph, I finally analyzed the circuit and tested the AC supplied to the diode bridge from the parallel inner coil: 20VAC goes to the motor under load (this wire is black on my Presto PopLite unit. Red is the hot wire. So before making the connections, each person should check and not depend upon wire colors :). So given that the resistance of the inner coil is 50 ohms, with a total voltage drop over this coil and the motor under load in series of 120VAC, the equivalent resistance of the motor is 12.5 ohms and the motor draw is 1.6 amps. So your selection of a 2 amp 24VAC transformer for the motor is perfect. Not isolating the inner coil from the fan would yield 100 watts (50V X 2A[100V/50ohm]) of coil heating whenever the fan runs, reducing the in-situ cooling efficiency, so your solution of running them in parallel produces 1550 watts of heat in my unit (the large coil is 11.4 ohms and in parallel they are about 9.3 ohms, 12.9A X 120VAC), and allows for room temperature air during cooling. Thanks once again for presenting your design and wiring. I will be working on it today and can't wait to try it out!
ChicagoJohn Lesson #1 Learned: Don't turn the fan speed down a lot with coil voltage high! The air flow is needed to remove heat from the coils. In making a trial batch (popcorn), I lost heating. Cause - blown aluminum fuse (> 240C). Lesson #2 Learned: Don't get frustrated if #1 happens, stop thinking, and "test" it by unplugging the fan from your 20VAC transformer and plugging it back into a 120VAC receptacle! Motor dead - coil smoked!
So with another brand new popper to be delivered today (and a spare heating assembly now wired to bypass all temperature controls -- perhaps to be used at a later date), I'll be trying again later today and tomorrow. This time, I plan to first chart curves of equilibrium roast temperature versus rheostat setting (at FULL 20VAC FAN SPEED) with no bean load, 25 gm green beans, 50 gm beans, and 100 gm beans, using whatever stirring or tilting I'd use in an actual roast (increasing the bean load will likely reduce airflow and increase equilibrium temperature.)
After completing this exercise, I hope to have a better understanding of how to balance air and heat during roasting and avoid another high temperature scenario.
ChicagoJohn An improvement, then success. The new Presto PopLite fitted to the proper rewiring (including high temperature shutoffs), I was not satisfied with the mixing of the green beans without stirring. The following fixed that: I bought an aluminum funnel at Ace Hardware ($3). It has a wide end diameter of 12 cm (~4.75 in). I cut a section of that such that the small end diameter was just over 3 cm and the large end around 7.4 cm. At the large end, I left four "tabs" of about 12mm length and width and I bent these back to fit the popper cylinder. I positioned this cone perfectly within the cylinder/blower entrance piece and then pop-riveted it in place using the tabs. This increases the angle above the angle of repose of the beans and I was able to do the roast with 100 gm of beans without stirring, running the motor at 24VAC input (note that this is only part way to the maximum voltage of the dimmer switch output!).
I decided to shoot for a 20 minute roast of Guatemala Atitian San Jeronimo Miramar, and I must say, that in terms of color uniformity it came out virtually perfect with just one or two shakes and no stirring, at just into 2nd crack.
If you have a popper that uses the bottom air supply instead of the circumference swirl, (such as the Presto PopLite I have) you may want to try installing this funnel shape just above the air inlet.
ChicagoJohn Would you mind posting, or linking to a picture of what you did. I am very curious about adding this mod to my setup.
Thanks.
Joseph Collins The following should link to an image on my Flickr account flic.kr/p/u7up2L and if you look in the lower right corner you will see an arrow above a horizontal line. Click on this and you should be able to download the image in whatever size you like. In addition, I'd be happy to e-mail you any other images you'd like that can be used as you wish without attribution. The only significant change I made to your modification would apply to poppers that have hot air introduced from a central port in the bottom (such as Presto PopLite), not for poppers that circulate air from ports around the circumference. E-mail Chicago.john@hotmail.com Thanks again, Joseph, for your outstanding videos without which I would have had a much steeper learning curve!
Thanks a million Joseph! My Poppery II should be here soon. Just need to stop by Harbor Freight and get a router speed controller.
Worked great. Thanks a ton!
Gracias muchas gracias, todo muy bien expmicado
Hey Joseph! Cheers for this video, I just have a question. Do you reckon it’s possible to use ONLY the ‘router speed control’ as an alternative to your original mod? (So heating to the full/off/variable switch & fan to the dimmer looking dial)
Not exactly.
The biggest thing is you don’t want the fan to get more than 24 volts.
You might be able to just run the fan off of batteries to the dimmer switch and only use the AC power for the element.
If you did this, you could desolder the diodes on the fan and wire the fan directly to make it slightly more efficient.
If you wired 4 6v lantern batteries in series you’d get 24volts, run that through your dimmer and just run the heating coil on AC.
Great Video!
Hey Joseph, really helpful video man Thanks for sharing! :) I have a question though; would this same mod and wiring be compatible with a West Bend Air crazy II as well? It's the only popper that I have at home. Thanks again!
Thanks for posting. Looks great.
So what are the voltages of the element and motor?
I would like to check the switched and variable controller I'm planning on using will be suitable and be able to handle it.
ChicagoJohn mentioned:
Motor = 20V ac
Element total = 120V ac
Is this correct and what the switch and controller should be rated for?
Why is there two individual elements? Is one thermostat controlled ?
+CakeCoffeeCafes The stats Chicago John mentioned were from his PopLite unit. I believe the motors are usually between 20 - 25 volts for various popper models.
Pay attention to the current (amperage) also, because the total watts is the number you want to look out for. Remember the equation P = V x I. The power(P) in watts is equal to the voltage(V) in volts times the current(I) in amps.
I installed a 2 amp 24VAC transformer for the fan, so that is 48 watts. Therefore a simple Light Dimmer switch that can handle up to 100 watts is perfect. The dimmer switch can handle the 120VAC because thats what a lightbulb operates on, however a 100W lightbulb only draws about 833 milli-amps.
However, the heating element draws the full 120VAC at about 13 amps so its around 1,560 watts which is far too much for a simple dimmer switch, that is why I used the router speed controller.
My unit does not have two elements, It only has one element, and there was no thermostat. The only thing the it has is a safety shutoff mechanism that is triggered by expansion of a small sliver of metal that disconnects the circuit when the heat causes it to expand. Some people have chosen to bypass this safety mechanism. I have had no need to do so.
If I just want to separate the heating element for the variable router control and keep the fan on a simple switch how do I do that?
Not much difference at all. You will still need the transformer because it basically does the job that the heating element did before you separated it.
Therefore, the only difference would be to install a simple switch instead of a dimmer switch.
You have to have the transformer because otherwise you will be sending ~115V directly to a 20v fan. The transformer steps the voltage down to 25v, which the fan can tolerate.
+Joseph Collins oh okay so I might as well install the dimmer too you are right! I might also install a different motor for the fan. I am thinking I found a weak dremel tool at harbor freight that might be a little more powerful that the fan in there.
+Joseph Collins I connected my fan to a 24 volt transformer for a computer and it died shortly. I think it worked well but it probably got too hot or something...
We need more information about your additional parts
Where did you get the transformer? RadioShack?
Yes, I originally purchased mine from radio shack. The part number is 273-1512 (25.2V Center tap 2.0A).
However, radio shack might not sell this anymore, which would be unfortunate.
I also found an equivalent of the radio shack transformer on mouser.com
www.mouser.com/ProductDetail/Triad-Magnetics/F41X/?qs=sGAEpiMZZMvwUzoUXIIvycT6np3HRZBQxmjkESKdeMA%3d
i am thinking i have a computer transformer/charger that is 19 volts. So that might work too and is already with a chord! its definitely cheaper.
Yes, that will work. Also, going that route you might be able to find a slightly higher voltage power supply at a thrift store for real cheap as well.
+Joseph Collins good thinking. Would I just clip of the diodes since those convert the AC into DC and since the transformer is giving off DC, I don't need them or should I just leave them?
Either way is fine, but clipping them is more work and shouldn't be necessary. If you clip the diodes, you have to re-solder the connection.
The diodes will create a minor voltage drop, so clipping them will be slightly more efficient, but I don't think it will make any significant difference.
Could you post a video showing how everything is wired in your box?
This IS that video. If you look at the drawing, it is showing the inside of my box.
My mod is very similar to the link here www.engadget.com/2006/02/28/how-to-make-a-popcorn-popper-coffee-roaster/ the only difference is that I added the rheostat.
The rheostat is a Router Speed Controller from Harbor Freight.
Joseph Collins Thanks. I noticed that you use a switch as an on/off for the heating section. My router speed control has a rocker switch with an "off" position, so I assume I could eliminate the separate on/off switch. Have you found there is an advantage to having the separate switch?
The only reason I have a separate switch is because the router speed controller was added after my original mod.
So yes you could essentially skip that switch and just use the one on the router controller.
Can the simple dimmer switch be replaced with the router speed control?
the speed control has a flip switch, do I still need to acquire another flip switch?
What temperatures are you reaching with this mod? This is what I have done as well and I reach just under 400° when I roast, even when I slow the fan down. I want to get up to 420°, but am not sure what to do in order to achieve such a temperature.
+Eric Busby I can definitely get 420°. If you have done exactly as I have done and you are not reaching that temp, then I would suggest adding more beans. More beans in the popper seems to trap more heat inside.
You can watch the video of me roasting at this link:
ruclips.net/video/jV7tZmNEjQQ/видео.html&feature=iv&src_vid=S4KXvGZOivA&annotation_id=annotation_1779959155
You will see that I reach 220°C (428°F) near the end.
+Joseph Collins
Adding more beans is what I have done, but when I have more than 100 grams the bed does not circulate well, or at all, without consistent/constant intervention on my part. At least, until the beans begin to yellow/tan. That is also with the fan speed at a constant and at its highest capacity for about 6 minutes (and up to 350° temperatures on my hands around that time). Even then, at the end of the roast, the beans generally don't reach any higher than 410° with 100-105 grams of coffee in the chamber.
My last roasts were 96 grams and they have performed reasonably well, though I would like a tad more development without baking the beans. The temperature did not exceed 397°, but the nutty and underdeveloped flavors of my roasts have diminished significantly because I have been keen on measuring temperature and plotting development. I want to tease out more floral and delicate notes which I would think could only result from better development.
+Eric Busby The other thing I did in my mod which might help with movement. I drilled LOTS of holes all over the case in order to allow more air inside. I also used a screwdriver to make each vent in the chamber slightly larger... not too much because otherwise the beans will get stuck.
It also could be something slightly different with your heating element as opposed to mine. The only other recommendation I can think of is try to get ahold of one of the 1500 Watt Poppery I's. The one I am using in this mod is a 1200 watt. The extra 300 watts might be just enough to get you that last bit you are looking for.
+Joseph Collins, I would have thought that drilling holes would be ineffective for retention of heat, so that is very curious to me. I will look at expanding the holes of the roaster chimney, though.
Also, what is the reading for temperature what you charge at? Does the temperature before you introduce the beans reach 400+°?
+Eric Busby, I preheat the chamber to about 270 degrees before adding the beans. The holes in the case don't affect the temperature of the chamber. However, the increase in airflow does affect the temperature.
The other important mod is the chamber extension.
One thing you could try, is instead of using a can like I used, try finding a tempered glass chimney from an old fashioned oil lamp. The longer the chamber is, the better the heat retention and the glass allows you to see your beans even though its very long.
You can buy the chimneys on HomeDepot.com