Print Thread
Help with "Turbo" Modding a West Bend Air Crazy
elmills
I started roasting with a "free" Presto Orville Redenbacher. It wasnt ideal, but it worked to learn. Completed about 30 batches before I started to worrying about it catching fire due to the chaff and oil buildup on the center grate.

Then I was able to a West Bend Air Crazy for $3. Roasting successfully with minor thermostat modifications.

Now trying to take it to the next level of control. I am attempting to "Turbo" the device like has been done by Clark Hughes http://www.hughes...e-roaster/.

I am attempting to follow this schematic www.hugheshouse.net/files/9813/2772/2230/coffee_roaster_mod.png

I have been successful with the fan control and with the general on/off of the heating coil, but haven't been able to determine the correct way to connect secondary coil.

I would prefer not to destroy/ruin the popper so I wanted to see if anyone to help guide me in the right direction.

See this picture elmills.net/wp-content/uploads/2014/03/AirCrazyWiring.jpg. This is a picture of my unit, but this is a picture of the device in a pre modded state.

I added a wire at point A and connected the wire from point E into the switch circuit. When wired into the switch I am able to turn the heating coil on and off, but I am trying to figure out which additional wires I should add and/or bridge to have the ability to turn the inner heating coil on and off.

Any suggestion or direction would be greatly appreciated. Want to learn the right/safe way to do this. Thanks.
New Roaster, trying to get an Air Crazy going.
 
Airhan
Does your roaster (popper) get hot enough to roast without the second coil? It shouldn't be necessary to wire it up as it's only purpose is to drop the voltage going to the motor in a unmodified popper.
Aaron
"Grind it like it did you some great injustice!"D.L.Clark
 
elmills
It appears to get hot enough. In some cases too hot. I was hoping to get more control by having the ability to turn the secondary heater on and off.

As a followup from last nights work.

After looking closely with a flash light point D doesn't connect to either heating coil. It originally connected to the thermostat. I removed the thermal fuse and the wire from point D.

When power is applied to points A and E the primary coils seem to glow, but it also appears to generate a faint glow in the secondary coil. This seems strange since these isnt anything connected to point C. Still working through the different options....
New Roaster, trying to get an Air Crazy going.
 
Lawnmowerman
A little more light. Where does the inner (motor) coil terminate when inspecting with lightv thats where your connections should be. Why does the second coil conduct when the first coil is the one connected? The outer coil and the inner coil are in close proximity. pouringThey work together. as a TRANSFORMER! Thats right. The heating element is the primary. When voltage is applied to the heating coil, a magnetic field is produced. The motor coil is positioned so the that the magnetic field from the heating coil induces a current in the motor coil ,or secondary. Hope this helps. Sorry 4 typos.
Bad coffee prevails when good coffee roasters stand by and do nothing.
 
creative-nickname
I'm not sure how to wire the elements so you can control them separately, but I wanted to raise one thing just in case you didn't already know it. If you rewire these so that a dimmer switch is placed in the circuit where the thermostat used to be, you can lots of control over the level of heat released by the element. I generally vary between 3/4 and full power using a rotary switch, and get great results. I just wanted to mention it in case you weren't aware of that solution!
 
elmills
Thanks for the answers and suggestions so far.

In response to #4, the inner coil terminates between point B and Point C in the picture above.

In response to #5, I have been able to find a cost effective dimmer that will handle the wattage of the heater element.

I went ahead and put everything together this morning and tried some test roasts. (without the secondary coil connected)

Before I started roasting I plugged in the system in a Kill-A-Watt. The circuit I was on provided 121 to 122 volts consistently. Running the fan at full speed used between .50 and .52 amps. When the heater turned on the amps drawn went to 7.75 to 7.85. This suggests that the heater is drawing pretty close of 900W.

I conducted 3 test roasts each was 1/2 cup ~75 to 80 grams. I tried to log the temperature and make a few notes as I roasted.
elmills.net/wp-content/uploads/2014/03/2014-03-15-22_24_32-Coffee-Roasting-Log-300x254.png

This experience was very different from roasting with my previous air popper, which took at most 5 minutes to complete the roasts. Will give the coffee a couple days to rest and then give it a try.
New Roaster, trying to get an Air Crazy going.
 
boris
I don't agree that inductance is turning on your secondary... people at MIT have been trying hard to transfer power wirelessly, I'm sure they'd be thrilled to learn of this configuration Grin
(Besides- if it's an open circuit, it can't dissipate power)

Given the resistance of the two wires, the faint glow makes sense. Primary is about 13ohms, secondary is about 60 ohms. P=V^2/R, so you should only expect about 20% of the power on the secondary coil. Sounds about right for a 'faint glow' - I think the situation is that you've accidentally applied power to your secondary somehow.

Given your initial results, this seems OK since your roast times are longer than you're targeting.
 
Jump to Forum: