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Can someone explain the air popper electrical technotalk?

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lawyervon
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Posted Tue Mar 4, 2008, 11:15am Subject: Can someone explain the air popper electrical technotalk?

Holy crap! No one told me I have to be an electrical whiz to home roast. I've been rotisserie drum roasting on my gas grill, and I'm wanting to try out the air popper method. I picked up a couple Poppery II's on eBay yesterday, but not I'm slightly freaked out by all the electrical talk all over the forums. Everywhere I turn, people are modifying electrical stuff and creating "frankenformers" just to roast. Variacs? Transformers? Am I going to burn my house down plugging this stuff in? Can someone people break all the technicalities of the Poppery II roasting down in layman English or give me a link to something that will explain all these electrical gadgets and what they're going to do for me and how to set them up without shocking myself and how to roast with them? OH! And if it matters, I tend to roast light -- City/City+. It seems like that matters because I read alot about people wanting to draw out the times on the lighter roasts and using all these gadgets to do that.

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Evazan
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Posted Tue Mar 4, 2008, 1:04pm
Subject: Re: Can someone explain the air popper electrical technotalk?

I know how you can feel. A lot of it can be intimidating at first. The way to understand it is to first understand your roaster and see how the things we do to modify them fixes the roasters short comings. I roast with a fresh roast so just about everything I say is also true for poppery's.

The biggest problem with air roasters is that they simply roast too fast. I started out roasting with an unmodified fresh roast and results were satisfactory but not great. The main problem was that I was hitting second crack at about 6 minutes into the roast. This results in a bean roasted on the outside but raw on the inside. This is when I started researching methods to slow the roast down.

The easiest but more expensive option is buying a variac. They can be had for around 100 dollars. A variac is a variable transformer. A transformer is something which can either raise or lower voltage so what a variac does is allow you to control the voltage going to the roaster. Since the heat is proportional to the voltage the variac can act as a temperature control. One problem with this is that if you simply plug the roaster into the variac the variac will be controlling both the temperature and fan speed. This is not a good thing because ideally at the lower temperatures you want a higher fan speed. What people do to fix this problem is open up their roaster and separate the heating element from the fan and only wire the variac to the heating element. Now you can control the temperature and fan speed stays constant which is a good thing. With this method you will be able to extend your roast time as long as you want.

The more complex method which you referenced in your post involves a transformer and a dimmer. What the transformer does is boost the voltage going to the fan by around 15 volts and then the dimmer allows you to control the speed of fan. This design will only cost around 20 dollars to implement and allows just about as much control as the variac. Increasing fan speed decreases temperature and vice versa.

My personal solution was to go with just one 1100 watt dimmer which can be bought for about 25 dollars. I wired this dimmer to the heating element of the roaster and it allows me to control the temperature. In my opinion it works just as good as the variac for 25% of the cost.

I am in my second year of studying electrical engineering and some of the stuff people discuss still confuses me. I had a question on the frakenformer which I would like to ask and hopefully rather then hijack your thread it would add to it.

PJK Said:

A good illustration of this transformer / dimmer setup by the "frankenformer" guy himself is here:

http://mdmint.home.comcast.net/coffee/fancontrolproto.htm

Phil

Posted April 20, 2007 link

I checked out that circuit and would love if someone could help explain it to me. I have never seen a transformer wired like that. It looks like it is wired to somehow give it self feedback. Why is it wired like this instead of how you would normally wire a transformer. I googled and checked my textbooks but have not been able to find any info on this method of wiring a transformer.

gime2much
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Posted Tue Mar 4, 2008, 1:24pm Subject: Re: Can someone explain the air popper electrical technotalk?

If you want to start out simple plug the popper into 50 - 100' 16 gauge extension cord (this provides a voltage drop) and use a small amount of beans to slow the roasting time. A variac or dimmer can always be added later but the above method can produce some very nice roasts.

Dan Brewer

lawyervon
Senior Member

Posted Tue Mar 4, 2008, 1:51pm Subject: Re: Can someone explain the air popper electrical technotalk?

Good info so far. How do I figure out what kinds of voltage or amps specs to look for when buying these add-ons? I'm guessing those numbers matter.

417coffee.com -- Tracking my experiences as a coffee lover and coffee homeroaster in 417land and beyond http://www.417coffee.com

ronnie_b
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Posted Tue Mar 4, 2008, 6:12pm Subject: Re: Can someone explain the air popper electrical technotalk?

Basically with a popper you are separating the heater circuit from the fan circuit. It's a bit easier with the P1 than with the P2 but it still can be done. http://www.geocities.com/Athens/Oracle/8104/popper.html is the best guide to modifying the P2. Read and understand this and you'll be a master modifier of a P2. The problem with the P2 is that the fan motor is 12v, while the motor in a P1 is 120v. Their are 2 heater coils in the P2, the smaller one is designed to drop the voltage to the motor and the transformer in the circuit is designed to replace the smaller heater coil. When I modified my popper, all I did was put a switch in the main heater circuit. You can put a variac rated for 1500 watts in the circuit instead of the switch. Turning the switch on and off to control the heat gets tiring. Check out http://homeroasters.org/php/forum/index.php for more info.

lawyervon
Senior Member

Posted Tue Mar 4, 2008, 7:01pm Subject: Re: Can someone explain the air popper electrical technotalk?

ronnie_b Said: The problem with the P2 is that the fan motor is 12v, while the motor in a P1 is 120v. Posted March 4, 2008 link Can you explain to me why it's a "problem" that the fan in the P2 is only 12V while the fan in the P1 is 120V? ronnie_b Said: Their are 2 heater coils in the P2, the smaller one is designed to drop the voltage to the motor and the transformer in the circuit is designed to replace the smaller heater coil. Posted March 4, 2008 link Can you explain the quote above to me in a little more plain English? lawyervon Said: How do I figure out what kinds of voltage or amps specs to look for when buying these add-ons? I'm guessing those numbers matter. Posted March 4, 2008 link I'm still trying to figure out the above question. You mentioned a variac rated for 1500 watts -- why 1500? I'm just not knowledgeable enough on the watts, volts, and amps piece to understand how they all work together so I can compare options on variacs and transformers and such.

417coffee.com -- Tracking my experiences as a coffee lover and coffee homeroaster in 417land and beyond http://www.417coffee.com

ronnie_b
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Posted Wed Mar 5, 2008, 6:09am
Subject: Re: Can someone explain the air popper electrical technotalk?

lawyervon Said:

Can you explain to me why it's a "problem" that the fan in the P2 is only 12V while the fan in the P1 is 120V?

Posted March 4, 2008 link

The problem is the ease of modification. The P2 is much easier to modify because all it's components are 120V. Splitting the heater and fan circuits requires moving only 1 wire rather than the circuit on the website above.

lawyervon Said:

Can you explain the quote above to me in a little more plain English?

Posted March 4, 2008 link

This part requires some knowledge of electricity. The P1 motor circuit has a heater coil and the motor. The motor is only 12V but 120V is fed into the circuit. The process of heating the popper by the heater coil reduces voltage going to the motor to a level the motor can handle. In the modified popper the transformer reduces the voltage to the motor and both heater coils are fed 120 volts.

lawyervon Said:

I'm still trying to figure out the above question. You mentioned a variac rated for 1500 watts -- why 1500? I'm just not knowledgeable enough on the watts, volts, and amps piece to understand how they all work together so I can compare options on variacs and transformers and such.

Posted March 4, 2008 link

I'm not an electronics teacher. http://www.howstuffworks.com/question501.htm gives a better explanation than I ever can. As for why 1500 wattss, most home circuits are rated for 1650 watts, 110 volts times 15 amps(the fuse value). A 1500 watt variac would be able to provide enough power to run the popper without blowing a fuse or circuit breaker.

OrPhEuS
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Posted Wed Mar 5, 2008, 7:37am Subject: Re: Can someone explain the air popper electrical technotalk?

Thank you for asking the question and thank you to all for clearing so many things up for me! I have a Poppery I and II and am getting close to wanting to modify them, but was put off by my complete knowledge of all things electrical. This thread has helped tremendously!

lawyervon
Senior Member

Posted Wed Mar 5, 2008, 7:43am Subject: Re: Can someone explain the air popper electrical technotalk?

Yeah - this is beginning to make sense. Sad thing is I bought 2 P2s on eBay before figuring this all out and and now, after this conversation, I'd rather have a P1. LOL Anybody want to trade 2 P2s for 1 P1?

417coffee.com -- Tracking my experiences as a coffee lover and coffee homeroaster in 417land and beyond http://www.417coffee.com

Frost
Senior Member

Joined: 26 Jul 2007
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Posted Wed Mar 5, 2008, 9:32am Subject: Re: Can someone explain the air popper electrical technotalk?

Modifying the P2 does not have to be so complicated (for reference, Ron has them backwards: the P1 has the 120 V fan.) I ran a P2 for many months with a variac on the heater and the fan directly plugged into 120V. The wiring is a bit more tricky (if you don't usually work on stuff like this, please get some help so you don't burn the house down) There are no lugs to connect so wire nuts or electrical tape and solder are required. I left the fan with it's heater coil intact and ran that to 120. The heater coil on a separate plug went to the Variac. (they share a common, so polarity must be observed.) The P1 has a more powerful and durable fan motor, and more powerful heater (which you don't really need for roasting). I have gotten years of service out of a poppery II, so don't let that stop you.

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