How-To: Make a popcorn popper coffee roaster
by Will O'Brien 
posted Feb 28th 2006 at 10:17PM
For today's How-To you'll need:
The hot air enters from the sides, allowing the beans to heat evenly and rotate. If the air enters directly from the bottom, the concentrated heat can become a fire hazard. We used a West Bend Poppery II for our roaster. Finding a suitable popper can be a challenge, but thrift stores often have suitable poppers for a few dollars. eBay is a great source for poppers, and Walgreens has reportedly been selling a suitable machine.
Normal air poppers won't get quite hot enough to fully roast coffee; some modifications are necessary . We'll be removing the "safety" features of the popper, so be aware that overheating the unit is possible (you know we're not going to be held responsible, yadda yadda). So, most poppers are built with two heating coils. One is used to reduce the voltage powering the fan motor. Sometimes one of the coils has failed, so test the popper to make sure it gets hot enough to pop popcorn. If the test resulted in a nice snack, it's probably in full working order.
When the project is done, the popper will have two separate circuits. The dimmer will be used to control the fan, while the switch will turn the heating coils on and off. For more detail peep our super-detailed schematic above, that should give you a very precise technical explanation.
Radio shack sells a couple of 25.2 volt center tap transformers. Make sure to get the 2.0 Amp version. If you pick up the 450ma version, the fan on the popper won't go fast enough (and the transformer will get pretty warm). Get an outdoor style plastic two gang electrical box (some people get a 3 gang and mount the transformer inside the box).
One of the hot leads will connect to one pole of the switch and the dimmer. The other will connect to one lead from the heating coil in the popper and a primary wire to the transformer. The other pole of the switch connects to the second lead to the popper's heating element. The other wire of the dimmer will connect to the other primary lead of the transformer. Finally, the two outer leads (yellow in the photo) are connected to the other pair of wires to the popper. Those two will be connected to the fan motor. Label each pair of wires "fan" and "heat" so you don't have to trace which is which later on.
Double check all of your wiring for safety!
The
popper needs to be opened up so that the fan can be separated from the heating element and the new wires from the
control box can be connected. Poppers vary, but the most use a few screws to hold the body together.
Our Poppery II used three phillips screws. Remove them and the top should easily separate from the base. The wiring will usually keep the heating chamber from being removed from the body until you remove the power cable strain relief.
On ours, the stress relief clip was easily pried up using a regular screw driver. If you can't get a screw driver under it, try a good pair of pliers. Don't worry about damaging the cable, we'll be replacing it. Once it's out, just pull the two halves apart and the heating chamber should now be easily removed.
The fan is attached to the bottom of the heating chamber with a few screws. Before we start, note the three wires that connect to the two heating elements, and the two leads to the motor. Cut off the power cord and cut all the wires near the crimp connectors.
Remove the three screws that hold the fan to the heating chamber. Now the heating chamber can be pulled apart to reveal the heating coils. When the chamber comes apart, you'll find a metal spacer and a fiber gasket, made of the same heat resistant material that the heating coils are mounted to. On reassembly, they should line up easily. Just in case, the order is: heating coils, metal spacer, fiber gasket, fan assembly.
The silver component with the red labeling is a thermal fuse. The black component with the brass track on it is a thermal switch. The thermal fuse is the SAFETY feature of the popper. If the popper overheats, the fuse kicks in and power to the heating coil is stopped.
The thermostat works by opening the contacts once a particular temperature is reached. Use a piece of stiff wire (uninsulated if it's not rated for the heat) and connect the terminal of the black wire to the terminal at the end of the thermal switch, next to where the white wire is terminated. Make sure it won't short across the other terminals! You have now DISABLED the SAFETY feature of the popper in order to gain full manual control. Now the popper can get hot enough to roast the coffee beans. It can also easily get hot enough to start a fire if you don't pay attention to it. In a nutshell: never run the heating element without the fan blowing. For safety, use a power strip with a circuit breaker in it.
Pull the two new pairs of power leads through the hole in the body previously used for the power cord. Connect the fan leads directly to the original fan wires. For the heater, connect the wires to their respective devices. Now reassemble the popper.
To add some stress relief, we use zip ties on the control wires inside and outside the popper body. There are two posts on the bottom of the fan base that fit into two molded towers inside the body. Once you line these up, you can put the top back on the body and screw the unit back together.
If you're satisfied with your wiring job, install the switch plate cover on your control box, along with the knob for the dimmer. Once you feel confident, test the unit out in safe conditions. We suggest placing it on concrete, away from anything flammable just in case! As long as you have good home wiring, a short will probably just trip a breaker. If you have problems, unplug it, make sure everything is cooled off and trace your circuits.
Now that the roaster is built and tested, you'll probably want to roast some coffee. One of our favorite coffee suppliers is Sweet Maria's.
Turn the fan dimmer all the way up and turn the heater on. Add green coffee beans until they just stop spinning around. Controlling the heat level will seem a bit un-intuitive. The faster the fan is going, the cooler the beans will be. In order to heat the beans up more, you need to slow down the fan slightly. It will take a batch or two of beans to get used to the process. When the beans have reached the roast level you want, crank the fan on high and turn off the heater to cool the beans.
Sweet Maria's has a short how-to on air popper roasting and a great pictorial showing the stages of roasting beans. Make sure you check them out. If you're not sure what kind of beans to get, try one of their sample packs. For testing out your new roaster, they offer a cheap coffee called Ugh! If you just want to try out the whole roasting experience, try sweet talking a local roaster into a few greens for educational purposes. Happy caffeination!
- Hot air popcorn popper (read on to make sure you get the right kind)
- Two gang plastic electrical box
- Two hole switch cover
- Basic wall dimmer
- Light switch
- Two computer power cables, or one fifteen foot extension cord.
- Radio Shack Model: 273-1512 Transformer or similar (25.2V Center tap 2.0A.) [Note: we originally grabbed the
wrong part number]
- Electrical tape or heat shrink tubing
- Soldering iron or twist on wiring nuts.
- Green coffee beans
Find the right popper
Not every hot air popper is suitable for roasting coffee. In order to safely roast coffee, the hot air chamber should look like this:The hot air enters from the sides, allowing the beans to heat evenly and rotate. If the air enters directly from the bottom, the concentrated heat can become a fire hazard. We used a West Bend Poppery II for our roaster. Finding a suitable popper can be a challenge, but thrift stores often have suitable poppers for a few dollars. eBay is a great source for poppers, and Walgreens has reportedly been selling a suitable machine.
Normal air poppers won't get quite hot enough to fully roast coffee; some modifications are necessary . We'll be removing the "safety" features of the popper, so be aware that overheating the unit is possible (you know we're not going to be held responsible, yadda yadda). So, most poppers are built with two heating coils. One is used to reduce the voltage powering the fan motor. Sometimes one of the coils has failed, so test the popper to make sure it gets hot enough to pop popcorn. If the test resulted in a nice snack, it's probably in full working order.
When the project is done, the popper will have two separate circuits. The dimmer will be used to control the fan, while the switch will turn the heating coils on and off. For more detail peep our super-detailed schematic above, that should give you a very precise technical explanation.
Radio shack sells a couple of 25.2 volt center tap transformers. Make sure to get the 2.0 Amp version. If you pick up the 450ma version, the fan on the popper won't go fast enough (and the transformer will get pretty warm). Get an outdoor style plastic two gang electrical box (some people get a 3 gang and mount the transformer inside the box).
Mount the transformer on the control box
We drilled two holes and used a pair of 6-32 nuts and machine screws. There are a couple of wire to wire connections. You can twist these together and use wiring nuts, or solder them and insulate them with electrical tape or quality heat shrink tubing.Prepare your power wires
You need four total or two pair of wires from the popper to the control box, and a pair of wires leading to a power plug. Keep in mind that green is used for a safety ground in AC wiring. If you're using a cord with a three prong plug on it, the other two will be the 'hot' wires.One of the hot leads will connect to one pole of the switch and the dimmer. The other will connect to one lead from the heating coil in the popper and a primary wire to the transformer. The other pole of the switch connects to the second lead to the popper's heating element. The other wire of the dimmer will connect to the other primary lead of the transformer. Finally, the two outer leads (yellow in the photo) are connected to the other pair of wires to the popper. Those two will be connected to the fan motor. Label each pair of wires "fan" and "heat" so you don't have to trace which is which later on.
Double check all of your wiring for safety!
The
popper needs to be opened up so that the fan can be separated from the heating element and the new wires from the
control box can be connected. Poppers vary, but the most use a few screws to hold the body together.Our Poppery II used three phillips screws. Remove them and the top should easily separate from the base. The wiring will usually keep the heating chamber from being removed from the body until you remove the power cable strain relief.
On ours, the stress relief clip was easily pried up using a regular screw driver. If you can't get a screw driver under it, try a good pair of pliers. Don't worry about damaging the cable, we'll be replacing it. Once it's out, just pull the two halves apart and the heating chamber should now be easily removed.
The fan is attached to the bottom of the heating chamber with a few screws. Before we start, note the three wires that connect to the two heating elements, and the two leads to the motor. Cut off the power cord and cut all the wires near the crimp connectors.
Remove the three screws that hold the fan to the heating chamber. Now the heating chamber can be pulled apart to reveal the heating coils. When the chamber comes apart, you'll find a metal spacer and a fiber gasket, made of the same heat resistant material that the heating coils are mounted to. On reassembly, they should line up easily. Just in case, the order is: heating coils, metal spacer, fiber gasket, fan assembly.
The silver component with the red labeling is a thermal fuse. The black component with the brass track on it is a thermal switch. The thermal fuse is the SAFETY feature of the popper. If the popper overheats, the fuse kicks in and power to the heating coil is stopped.
The thermostat works by opening the contacts once a particular temperature is reached. Use a piece of stiff wire (uninsulated if it's not rated for the heat) and connect the terminal of the black wire to the terminal at the end of the thermal switch, next to where the white wire is terminated. Make sure it won't short across the other terminals! You have now DISABLED the SAFETY feature of the popper in order to gain full manual control. Now the popper can get hot enough to roast the coffee beans. It can also easily get hot enough to start a fire if you don't pay attention to it. In a nutshell: never run the heating element without the fan blowing. For safety, use a power strip with a circuit breaker in it.
Pull the two new pairs of power leads through the hole in the body previously used for the power cord. Connect the fan leads directly to the original fan wires. For the heater, connect the wires to their respective devices. Now reassemble the popper.
To add some stress relief, we use zip ties on the control wires inside and outside the popper body. There are two posts on the bottom of the fan base that fit into two molded towers inside the body. Once you line these up, you can put the top back on the body and screw the unit back together.
If you're satisfied with your wiring job, install the switch plate cover on your control box, along with the knob for the dimmer. Once you feel confident, test the unit out in safe conditions. We suggest placing it on concrete, away from anything flammable just in case! As long as you have good home wiring, a short will probably just trip a breaker. If you have problems, unplug it, make sure everything is cooled off and trace your circuits.
Now that the roaster is built and tested, you'll probably want to roast some coffee. One of our favorite coffee suppliers is Sweet Maria's.
Turn the fan dimmer all the way up and turn the heater on. Add green coffee beans until they just stop spinning around. Controlling the heat level will seem a bit un-intuitive. The faster the fan is going, the cooler the beans will be. In order to heat the beans up more, you need to slow down the fan slightly. It will take a batch or two of beans to get used to the process. When the beans have reached the roast level you want, crank the fan on high and turn off the heater to cool the beans.
Sweet Maria's has a short how-to on air popper roasting and a great pictorial showing the stages of roasting beans. Make sure you check them out. If you're not sure what kind of beans to get, try one of their sample packs. For testing out your new roaster, they offer a cheap coffee called Ugh! If you just want to try out the whole roasting experience, try sweet talking a local roaster into a few greens for educational purposes. Happy caffeination!
Reader Comments (Page 1 of 1)
wilson @ Feb 28th 2006 10:32PM
Now convert your George Foreman Grill into a device that automatically dials 911 when your popcoffee roaster sets the house on fire.
Joseph @ Feb 28th 2006 10:42PM
our george foremans are converted into low power seat warmers...using the same rheostat method.
Cedrik @ Feb 28th 2006 10:44PM
This is an INSANE mod! :) I love it, as always. Hack a day is my graceland for projects like this.
Will @ Feb 28th 2006 10:55PM
I've been a loyal Sweet Maria's customer for years. I've never, ever been spammed at the address I use for ordering from Sweet Marias.
There is nothing like the satisfaction of home-roaseted coffee once you get it right. Wilson's right too, never ever leave a roast unattened and keep a fire exstinguiser around. Better safe than sorry.
Christopher Robbin @ Feb 28th 2006 11:03PM
I've never been spammed after shopping their either. I also signed up for the newsletter.
Michael Geary @ Feb 28th 2006 11:31PM
This is nuts. If you have any interest in roasting your own coffee, do yourself a big favor and buy an i-Roast 2 from www.sweetmarias.com or www.coffeebeancorral.com.
The big problem with a popcorn popper is chaff. When you roast coffee, it throws off a large amounts of this papery skin. It gets everywhere and makes a big mess. The i-Roast has an excellent chaff collector that gets rid of this problem.
I've been roasting for years. I did start out with a popcorn popper, but it's been so much more fun with an i-Roast.
DigMe @ Feb 28th 2006 11:45PM
"After entering our e-mail address on this site we received 564 e-mails per week."
The only way that could have happened is if you entered your email in the spot to sign up for SM's homeroast listserv group. Nice work, genius. Do yourself a favor and don't even CONSIDER a possibly flammable electrical mod.
Frank @ Mar 1st 2006 12:25AM
as a sweet maria's customer, i can also attest to never *ever* being spammed by them. their coffee kicks ass, too. i wouldn't necessarily go to all the trouble shown in this hack, either -- sweet maria's site can give you the low-down on just using a thrifted popper and that's it. oh -- and the one thing i don't see mentioned here is that roasting your own coffee is MUCH cheaper: unroasted beans cost about half the price of roasted ones.
Mik Ishmael @ Mar 1st 2006 1:21AM
I just got 3 # of beans from Sweet Maria's. no spam from them here.
Peter @ Mar 1st 2006 2:24AM
I like sweetmarias too. I never got spam, and I always use a unique email address at my domain for online orders. So there.
BTW, I am selling my coffee roaster, which is probably cheaper, than putting the above project together :-) craigs: http://losangeles.craigslist.org/hsh/137980281.html
Mark @ Mar 1st 2006 3:28AM
Woot. I knew we should have done a video podcast way back in podcast #5 or #6 when we did an audio how to on this very subject.
For the more hardcore types, seek out the original West Bend Poppery I (or just West Bend Poppery) from the 1970s - all metal inside, power switch, hackable so you change it from on.off to on.on-no-heat for your own cool down system. I had one but recently lent it to a friend.
Hey, you want really hardcore, check this baby out - coming soon to N. America (but not quite yet):
http://www.coffeegeek.com/forums/coffee/homeroast/210588
Love it when Engadget covers coffee. Most of the time, it's cool, hip stuff (unlike the wonk coverage I got over at that, uh, other site when they talked about my take on grinders in the NY Times a short while ago).
Mark @ Mar 1st 2006 3:31AM
Oh one more comment - that thing about side air vents (ie, how it must look like that, pic 2)? Pretty much proven as bunk. On SM's own mailing list years ago, several people ran serious tests with bottom-vent poppers with no bad effects. Like fire.
Keep in mind, you're ultimately using a device for a purpose other than its intent, so things like, I dunno, burning down your kitchen? Yeah, it could supposedly happen, and you only have yourself to blame ;)
jason @ Mar 1st 2006 6:55AM
Hey: I can show you how to convert a Farberware coffee pot into a still. Vodka, gin, brandy etc from a coffee pot:)
Ralph Martone @ Sep 22nd 2006 3:00AM
Jason,
Sure would like to share your knowledge on the Faberware coffee pot.
Respectfully,
Ralph
SteveJ @ Mar 1st 2006 9:21AM
If you don't wish to roast your own just yet, another option is to buy from an online source that roasts to order. I like baltcoffee.com (Baltimore Coffee & Tea Company), in part because they are local to me, but also I like that they do not roast everything into near cinders (i.e. Starbucks and Pete's Coffee). Most of their roasts are medium. Excellent quality coffee, roasted to order. I buy 2 or 3 pounds of coffee from them every couple weeks. The roast date is noted on the bags. Of course some day I want to try roasting, but the one time I experienced roasting (by someone else), the smell was horrendous. Pretty unbearable. I don't have, then, a good place to do the roasting. Do people run their roasters outside, or what do you do to avoid stinking up the house?
BBOCK @ Mar 1st 2006 9:24AM
It might be worth the $120 or so that it costs to buy a coffee roaster in order to avoid the risk of burning your house down. Added advantage: real roasters have timers.
Moe Rubenzahl @ Mar 1st 2006 11:49AM
One of the more thorough treatments on this I have seen. I tried to do this once, with mixed success, Definitely fun but in the end, I bought a commercial product, the FreshRoast 8. Works and has not yet started any fires ;-)
By the way, roasting your own coffee is a GREAT improvement -- much better coffee (and cheaper, too!) Here is a primer I wrote that tells how to get started:
http://feedme.typepad.com/my_weblog/2005/04/roasting_your_o.html
Brent - Roasting in an SC/TO @ Mar 1st 2006 12:10PM
Excellente instructions! This is the kind of info I needed several years ago when trying to mod a popper. Electrically inept without step by step instructions.
Even better: the Stir Crazy/Turbo Oven setup for homeroasting - larger batches and more control. All for under $100.
Sweet Maria's: excellent source for green beans and information. They really know their stuff. You won't get inundated with email by ordering from them. They do have an email newsgroup you can sign up for (completely separate from ordering): informative, somehwat entertaining, very heavy email.
Brent
MAS @ Mar 1st 2006 12:19PM
The original West Bend Poppery had an on/off switch on the front and didn't require ANY modification to roast coffee.
http://ineedcoffee.com/05/poppery/
Randy R @ Mar 1st 2006 12:20PM
For better chaff collection, the same mod can be made to a Freshroast coffee roaster, which sweetmarias.com also sells. One of the steps to the freshroast mod is to bypass the timer (it controls the heat and the fan.)
Two important tools for home roasting are a timer of some kind (digial watch?) and a log, so you can record and reproduce your roast profiles. (Different kinds of coffee beans have different ideal profiles.) A good digital temperature guage also helps, but you can also do it by ear.
Mark @ Mar 1st 2006 7:12PM
to #20
The mod I was talking about on the original WBP was that the on off switch's function was changed from on / off to on with heat / on without heat. Built in cooling cycle. Wallah.
Adrian Hains @ Mar 2nd 2006 11:15AM
Glad to see more folks seeing this info, I love my popcorn popper roasters. I always check the local goodwill when driving by, and have about 6 of them now in the storage shed. I bust them from time to time, so I like to have a pool of them ready to go. :)
Regarding chaff, this has not been an issue for me. I place a metal screen colander in front of the popper. The chaff blows out of the popper and into the colander. When the coffee is about done, I dump it into the garbage and then use the same colander for dumping the hot beans into. Works great.
Regarding buying green beans, I have bought and sold via the green coffee co-op (http://www.greencoffee.coop/). They are definitely the cheapest route to go since no one is making a huge profit, and I highly recommend them. I think Sweet Maria's is great for getting a sampler pack to try many varieties.
sam @ Mar 2nd 2006 4:18PM
Sweetmarias is awesome!!! I love reading about all of Tom's trips to coffee plantations in other countries - this guy really loves what he's doing.
I roast with a totally unmodified popcorn popper and it works great. Do it on the stove right under the fan and you don't get a smokey kitchen. When you're done hold the beans in a colander up to the vent fan to suck the air through and it cools in less than a minute. Finally, grab the vacuum clean with the hose attachment and suck up the chaff...takes a total of 15 or 20 minutes with pretty much no mess or smoke.
coffee.infodiv.com @ Mar 5th 2006 9:43AM
Brilliant idea. It would be even better if you could integrate both modules as one, concealing the power cables between the modules.
SEJAHTERA @ Jun 3rd 2008 10:58PM
Thanks for chance to share about coffee roaster technology
We need learn about coffee roaster technology
We have waiting new Technology for it
Thank you
Regards
SEJAHTERA Girsang
Corey @ Jun 3rd 2008 3:47PM
I wasn't feeling overly adventurous on this project, but does anyone know if I could replace the heat switch with another dimmer?
Ross @ Jan 6th 2009 4:23AM
Hi Corey,
I installed a plain ol' low-wattage dimmer for the heat switch instead of a standard light switch and it worked just fine. It allowed me to adjust the heat so that it wasn't blaring hot no matter what; great for bean variations and range in roasting time.
-Ross
Gabe A. @ Mar 14th 2006 1:56AM
I was just about to write and complain that the 12V center tap transformer originally listed didn't let the fan run fast enough. I found that the $10 Walgreens Popcorn popper works well(a bit on the fast side according to other forums) without any mods. the project above would allow me to turn the heat on and off to slow down roasting. Back to Radio Shack....
P.S I couldn't find a plastic box like the one used in the article anywhere.
ButtWhiskers @ Mar 23rd 2006 4:20PM
The plastic gang boxes are available at any Home Depot or hardware store, where the light switches, dimmers, and electrical outlets are.
I remove the plastic top piece of the popper and jam a soup can with it's top and bottom removed to extend the roast chamber. Use pop rivets to attach a mesh strainer with a hole cut out of the bottom to the sides of the soup can about 1" from the top of the can. You can then set a slightly smaller mesh strainer upside down in the first one and all of the chaff is contained. Near the completion of the roast, use a dustbuster to suck out all the chaff from the strainer, remove the strainer/can assembly (need to insulate the handle as it can get pretty hot), and dump the beans.
When you are entirely hooked on homeroasted coffee, upgrade to the StirCrazy/turbo oven or a BBQ drum roaster. You can get really good deals on green beans of the highest quality at greencoffee.coop and greencoffeebuyingclub.com
-
John @ Mar 24th 2006 9:12PM
What do you do with the third lead (black) on the secondary side of the transformer?
Coffee Savant @ Mar 26th 2006 8:48AM
You can use a whirly-pop type popcorn popper to roast coffee on a BBQ, single burner, open flame, etc... preferably outdoors. Or a cast iron skillet or a heavy pan like an iron clad or a wok. I generally pre-heat to 400 (check with a temp. probe that goes up to 550).
Jonathan Mitschele @ Mar 26th 2006 11:26AM
The two dimmer switches I tried both burned out instantly. The specifications for both said not to use for controlling motors or with transformers, but I believed what I read about dimmers - which was not true.
You don't need a dimmer to control the fan. What you need to do is use enough beans to control the airflow. If beans are moving in a circle, add more until they are jumping about randomly. Too many, and they don't move. Look at http://www.ineedcoffee.com/05/poppery/ for lots more information. I eliminated only the thermostat from the circuit, leaving the thermal fuse in place, and with sufficient beans the outcome was just fine; without, I just got baked beans.
Will O'Brien @ Mar 26th 2006 12:02PM
That's very odd. I've built a couple of these, and had no problems with the dimmers. The transformer seperates the dimmer from the motor, so that should't be a problem. The latest one used the cheapest dimmer I could find from wally world - it's worked great for a couple of years.
Light dimmers are not rated for motor control - the transformer should protect it.
If it burnt out 2 dimmers, something is is probably going on. Perhaps a bad transformer?
Giraffe @ Apr 12th 2006 12:45AM
I am about to make this mod on my Poppery 2. A couple of questions about the transformer: The two black wires are the input from the dimmer/hot, and the two yellow wires are the output to the fan, correct? And is the wire between the two yellow ones a ground?
Giraffe @ Apr 12th 2006 9:29PM
Never mind. I found out that the black wire between the two yellows is a center tap and is not used in this application.
Julian @ Oct 5th 2008 11:42AM
Wow --after a month of working and three screw ups--because I didn't follow the directions and two too small transformers later I got a great roaster--Got to use the Radio Shack transformer because it's heavy duty--I tried home depot ones and it burnt out fast. I used two switches and two timers---One switch and timer for the heat coils and the others for the fan--Now I set the fan timer for about 5 minutes longer than the heat and wow -----self service roast.
Happy roasting
Julian
Bee Hof @ May 30th 2006 12:27AM
Nice job of explaining this mod. I used a West Bend Poppery II for the first time today and I did NOT need any of these mods. I'll think about adding an inline on/off switch to the cord though.
Thanks
zlemonz @ Jun 17th 2006 7:30PM
What do you do with the red lead to the smaller heater coil?
bcparfitt @ Sep 9th 2007 10:33PM
Hmm... I had the same question. I have the white and black leads to the larger heater coil wired to the on/off switch but was unsure about the third red lead for the smaller heater coil. Anyone have any suggestions on this?
Ryan @ Sep 13th 2009 2:32AM
I just finished roasting some beans after making this modification to one of the poppers from Walgreens. It is called the "Kitchen Gourmet". I put in two dimmers. After roasting I don't really feel I needed the dimmer on the heat, as I kept it up as high as it could go for a good roast... Is there any reason why using a dimmer is not safe compared to using a switch in this application?
Seeing how this was the first electrical project I've ever done...
Bear with me if the things that troubled me are completely obvious to you...
Some things I would have liked to know before I had started:
1) In the instructions under the Prepare your power wires section:
"You need four total or two pair of wires from the popper to the control box, and a pair of wires leading to a power plug. "
Even though it isn't in the list of things you need to have for the project(!) you need some wire... I bought 18 gauge wire and used this to create "two pairs of wires from the popper to the control box." The "pair of wires leading to the power plug" was an 15 foot extension cord.
2) I'll go through the Main part of the How-to adding things in parenthesis...
"One of the hot leads (This is one of the two wires that is coming off of the extension cord) will connect to one pole(or wire on each) of the switch and of the dimmer. The other will connect to one lead from the heating coil (doesn't seem to matter which one of the two... But I thought, "there are three!" the red one in my case is the one that is sort of in the middle of the other two. So I guess you can tell which one you can tape off because it isn't at the beginning or end of the coil connections... the, in my case, red one I just taped off like someone above suggested...) in the popper and a primary wire to the transformer(the primary wires or leads are the two that are on the other side of the transformer from the yellow ones).
The other pole (wire) of the switch connects to the second lead (again your extra wire you have comes in here) to the popper's heating element (coil).
The other wire of the dimmer will connect to the other primary lead of the transformer. (again, the ones on the other side from the yellow ones or the 'outer leads' as he calls them)
Finally, the two outer leads (yellow in the photo) are connected to the other pair of wires (by other pair of wires he is talking about the 18 gauge wire you bought) to the popper. (I just taped off the wire between those two yellow ones) Those two will be connected to the fan motor. Label each pair of wires "fan" and "heat" so you don't have to trace which is which later on.
3) My popper (the Walgreens popper) has a little different heating coil setup... At least I think. The thermal switch (also called the thermostat) has this piece of metal that I removed so that it doesn't flip the switch. So I bypassed the thermal fuse with a piece of bare wire that just went from one side of the fuse to the other. In the walgreens popper it doesn't look like it would work to connect it to the thermal switch like in his popper.
As this little project has spurred more interest in things like this for me...Could someone explain what function the transformer is performing in this application and what would happen if there wasn't a transformer there?
I hope these things help someone in their attempt to do this.
The benefit I see to doing this modification to this particular popper is that I don't have to look around for the old school poppers and can just go to Walgreens and get a few of them for 10 bucks each and not have to worry about roasting too much because I can just hook up a new one to the box.
-Ryan
Ryan @ Oct 16th 2009 11:06AM
Update:
I took out the wire I put in that bypasses the thermal fuse.
Perhaps it is different with this type of roaster, but it still gets plenty hot and it is a whole lot safer to have that fuse in there...
Also replaced the dimmer on the heater with a switch... much better.
Thanks again for posting this mod.
-Ryan
Alan @ Jan 2nd 2008 6:07PM
Ok so, I dont think i did anything wrong with this mod. Used the popper available at walgreens. Tried this setup with the red wire from the heating coils connected to the red wire on the fan still. Also tried it with the red wire from the heating coils not connected to anything at all.
I now have 3 broken popcorn poppers and no roaster.
What am i missing here?
Alan @ Jan 2nd 2008 7:43PM
Scratch that. I found my mistake.
For other's reference. I just taped off the extra red wire and things seem to be working nicely.
Thanks for the writeup!