Air Popper Modifications -Installing an Off Switch

If you choose to alter your air popper you assume the risk that it will no longer work as it was designed to, that it might not work at all, that you might injure yourself in performing these tasks or in using the altered device. This information is here for you to peruse, but Sweet Maria’s accepts NO responsibility in what the results may be.

Read Wes Cherry’s comments at the bottom of this page, too!

Turning the Main Heating Coil Off

One drawback of air popper roasting is that it offers no control over the heat. You can gain some by being able to switch the main heating coil off and thereby prolonging the roast process, or modulating the temperature. There are two heating coils. The small inner one you will see when you follow this process is unaffected by the switch. It only heats the popper to about 150 degrees by itself. The thicker outer coil is the one you will be able to turn off. It is responsible for at least 200 or 300 degrees of the heat.

There are three screws holding the plastic top to the plastic bottom, you will see them when the popper is inverted. You need a small phillips screwdriver to remove them. When you separate them the inside works will come out as a unit. The top and bottom is held together with 3 more screws that are even smaller. As this comes apart, make good observations as to how all this stuff will go back together.

After you separate them you will see a small plate, which contains the heating element above the fan and motor, and on the plate will be the thermostat. A small brass thing about 3/4″ long with contacts on one side. The goal here is to seperate the contacts and solder a wire to each seperated end of it. The wires will go to your switch (Radio Shack offers many kinds) You can either wedge something nonflammable between the contacts to keep them apart or actually break off the one contact and then solder on your wires. Your new wires will need to follow the existing ones out of the inner casing. I suggest using the thinnest wire you can. Good Luck!

Several roasts after I first tried this, one of the solder points I had made came loose and I had to take the whole thing apart. Later I tried to rewire the thing so that the switch would shut off both heating coils. I plugged it in and was promptly shocked. Then I took it apart again and tried a different approach. I put it back together, plugged it in, and heard a loud POP. One Poppery ll bites the dust. The instructions above DO work, but don’t push your luck if, like me, you don’t really know what you’re doing. I suggest that you perform this with the realization that you may never roast coffee with this popper again!

The best solution would be some kind of variable potentiometer that would allow you to set the main coil at whatever temperature you want it to be at. Any ideas, all you EE’s out there???

Thanks to Ted Cary for his email. He told me how to do this!


Postscript: Some Wise Words from Wes Cherry

From: “Wes Cherry” <[email protected]> To: <[email protected]> Subject: Popcorn popper modifications (switch)


I saw you instructions on how to modify a WB poperry II to add a switch. I have a couple warnings and a modification that might be helpful.

First, make sure any wire that you use to connect the thermostat to the switch are rated for at least 200 deg C. I don’t believe wire of this rating is easily available. Also, you should NOT use solder so close to the heating elements. Most solders melt at around 220 deg C, (420 F). Finally make sure the switch is rated for at least 10A at 120V (preferable 15A at 120V or 10A at 220V).

Some of the above problems can be avoided by installing the switch wire connections away from the heating element. On my WB PII there is a small circuit borard below the motor. Coming out of that board is 3 wires, Red, Black and White. You want to cut the white wire and install the switch there (ok to use solder here). Also to get proper heat I had to defeat the thermostat. I bridged the thermostat by wrapping a bit of 16 gauge stranded wire around each of the thermostat’s solid copper leads and crimping it with some pliers to get a good connection.


“Pee for enjoyment, not for employment”

Here’s the possibilities for air popper modification. This is a controller box that controls on-off, coil 1, coil 2, and the fan (variable speed) independently. It was built by Jeff Mieleke.

modified popcorn popper for coffee roasting
modified popcorn popper for coffee roasting

For more infomation, peruse the links on our “readings and resources” page…

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