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Another Modded Presto Poplite Roaster
IKR
Top  #1 Print Post
Posted on 10/17/2015 10:53 PM
Hey all,
I received so much good information from the site I figured I'd share my modifications to my Presto Poplite roaster.
Parts:
1) BINZET AC to DC 24 Volt 3 Amp Power Supply Adapter Converter Regulator w/ 5.5mm x 2.1mm DC Plug connector
2) 24V 3A 72W Wall Plug Switch for DC24V 10M 5050 LED Strip Lights (not used, failed in 30 seconds of testing)
3) DROK? Motor Speed Control Driver Board 12V-60V 10A 420W PWM Controller DC 12V 24V 36V 48V Variable Volt Regulator Cooling Fans Dimmer Governor Pulse Width Modulator LED Indicator Switch Function (to control airflow)
4) Drill Master Router Speed Control Dial (to control heating coils)
5) HDVD 10 inch(30cm) 2.1 x 5.5mm DC Power Pigtail Female
Modifications:
1) Separated heater coil and fan circuits
2) Added the heater coil wire that was going to the blower motor to the return/common wires (The two coils then form a simple parallel resistor network which calculates to about 9.4 ohms)
3) Removed electric motor diode bridge
4) Drilled additional cooling holes in base of popper
5) Installed 3? HVAC Heater adapter pipe as chimney extension
Taking 24V DC to the Motor Speed Controller allows me to move 106g batches of beans with good fluid-bed action. I'll see what happens with the motor life but the diode bridge on the motor crapped out on me any way. Only a few pounds through it but so far so good. For actual guidance on modding a Presto Poplite popper I'd recommend perusing ChicagoJohn or kaffeine's excellent threads. Attached are some photos of my roaster. The photo with the beans pictured is the current configuration. The cheap dimmer switch failed within 30 seconds of testing. Happy roasting all.
IKR attached the following images:
frankenstein3.jpg frankenstein4.jpg frankenstein2.jpg
 
kaffeine
Top  #2 Print Post
Posted on 10/30/2015 7:22 PM
It brings me great joy to see someone following in ChicagoJohn and I's footsteps. I wish you many great roasts!

Your post doesn't mention, and I can't tell in your pic; did you do ChicagoJohn's funnel mod in the chamber? It creates wonderful vertical rotation-agitation. A friend and I ran ours next to each other, mine with and his without, and the difference was quite noticeable at 91g roasts. If you haven;t done this mod I highly recommend it... Just some unsolicited advice ;)

Happy roasting!
I wake, therefore I coffee
 
ChicagoJohn
Top  #3 Print Post
Posted on 10/31/2015 11:38 AM
I really like what you did here, especially the 3A 24VAC transformer -- the motor draws 2.5A and not realizing this, I struggled with it. Your set up looks great and I bet you get a lot of great roasts from it. I've done many with mine so far. Thanks for posting your information.
So many beans; so little time....
 
IKR
Top  #4 Print Post
Posted on 11/01/2015 2:33 PM

Quote

kaffeine wrote:

It brings me great joy to see someone following in ChicagoJohn and I's footsteps. I wish you many great roasts!

Your post doesn't mention, and I can't tell in your pic; did you do ChicagoJohn's funnel mod in the chamber? It creates wonderful vertical rotation-agitation. A friend and I ran ours next to each other, mine with and his without, and the difference was quite noticeable at 91g roasts. If you haven;t done this mod I highly recommend it... Just some unsolicited advice ;)

Happy roasting!

Thanks a lot for the suggestion and your post on your roaster. I have not done the funnel modification but it is on my to do list. I do stir when I initially start my roast until the beans lighten but doing the funnel modification would fix that. I do 105g charges so it would be even more helpful in my case. Let's see how long our Roasters will keep going. I am very happy with my roasts and hopefully you're still pleased with yours as well.
IKR
 
IKR
Top  #5 Print Post
Posted on 11/01/2015 2:46 PM

Quote

ChicagoJohn wrote:

I really like what you did here, especially the 3A 24VAC transformer -- the motor draws 2.5A and not realizing this, I struggled with it. Your set up looks great and I bet you get a lot of great roasts from it. I've done many with mine so far. Thanks for posting your information.

Thanks for posting the information you have on your roasters as you continually improve them. I went through some struggles as well with my previous transformers(2) which resulted in the diode bridge on the motor completely burning up. So far so good on the current setup which has gone through a few pounds of beans so far. I plan on some more mods but right now I'm just playing with different roast profiles on a wide variety of beans. I'm drinking coffee just as good or better than the local micro-roasters I used to buy from at a much cheaper price. Good luck on your next round of improvements and please keep posting the updates.
IKR
 
ChicagoJohn
Top  #6 Print Post
Posted on 11/02/2015 9:10 AM

Quote

IKR wrote:

[quote]ChicagoJohn wrote:

I went through some struggles as well with my previous transformers(2) which resulted in the diode bridge on the motor completely burning up. So far so good on the current setup which has gone through a few pounds of beans so far.IKR


Good to see you got it working! I can't imagine why the transformers would have caused the diodes to go out, unless the motor was running slow at the supplied voltage: If the weight of the beans were to smother the air from entering the roasting chamber -- in effect simulating a plugged grid, some of the hot air might travel downward in the direction of the motor and original diode bridge at the bottom. That is the only other exit route. The original diodes are something like N4001's which are very small and would heat up rapidly from ambient air, faster than the motor housing. Would you be able to share the ratings on the first two transformers you used and had a problem with? I'd like to understand how they caused the result you experienced.

Again, glad to see you have it running well and have put a couple of pounds through it. As for my two, I think I've reached the end of the road on further mods and will hopefully be able to look forward to roasting and enjoying the result smile
So many beans; so little time....
 
IKR
Top  #7 Print Post
Posted on 11/02/2015 10:52 PM

Quote

ChicagoJohn wrote:

Quote

IKR wrote:

[quote]ChicagoJohn wrote:

I went through some struggles as well with my previous transformers(2) which resulted in the diode bridge on the motor completely burning up. So far so good on the current setup which has gone through a few pounds of beans so far.IKR


Good to see you got it working! I can't imagine why the transformers would have caused the diodes to go out, unless the motor was running slow at the supplied voltage: If the weight of the beans were to smother the air from entering the roasting chamber -- in effect simulating a plugged grid, some of the hot air might travel downward in the direction of the motor and original diode bridge at the bottom. That is the only other exit route. The original diodes are something like N4001's which are very small and would heat up rapidly from ambient air, faster than the motor housing. Would you be able to share the ratings on the first two transformers you used and had a problem with? I'd like to understand how they caused the result you experienced.

Again, glad to see you have it running well and have put a couple of pounds through it. As for my two, I think I've reached the end of the road on further mods and will hopefully be able to look forward to roasting and enjoying the result smile


My 1st transformer was a generic 24VAC 2.5 amp model connected to the diode bridge which was still on the motor. The motor ran slow but it was the transformer which failed the first time. My second transformer was a generic 24VAC 5 amp model connected to the diode bridge. The motor ran at normal speed but the diode bridge failed after a few minutes of running. I still have the 2nd transformer but so far so good with my current set up.
Happy roasting
 
ChicagoJohn
Top  #8 Print Post
Posted on 11/03/2015 7:37 AM

Quote


My 1st transformer was a generic 24VAC 2.5 amp model connected to the diode bridge which was still on the motor. The motor ran slow but it was the transformer which failed the first time. My second transformer was a generic 24VAC 5 amp model connected to the diode bridge. The motor ran at normal speed but the diode bridge failed after a few minutes of running. I still have the 2nd transformer but so far so good with my current set up.
Happy roasting


Thanks for that information. Who knows what happened: Your 1st one should have worked, but unfortunately components are often not rated correctly as I've seen in several instances. In any case, I'm glad it's working for you now. After hearing about your experience and considering possibilities, I think it's probably best to move the rectifier circuit outside the popper because their position on the motor could get very hot very quickly if the air isn't flowing properly through the popper.

Happy roasting to you as well.
So many beans; so little time....
 
IKR
Top  #9 Print Post
Posted on 11/03/2015 12:38 PM

Quote

ChicagoJohn wrote:

Quote


My 1st transformer was a generic 24VAC 2.5 amp model connected to the diode bridge which was still on the motor. The motor ran slow but it was the transformer which failed the first time. My second transformer was a generic 24VAC 5 amp model connected to the diode bridge. The motor ran at normal speed but the diode bridge failed after a few minutes of running. I still have the 2nd transformer but so far so good with my current set up.
Happy roasting


Thanks for that information. Who knows what happened: Your 1st one should have worked, but unfortunately components are often not rated correctly as I've seen in several instances. In any case, I'm glad it's working for you now. After hearing about your experience and considering possibilities, I think it's probably best to move the rectifier circuit outside the popper because their position on the motor could get very hot very quickly if the air isn't flowing properly through the popper.

Happy roasting to you as well.


I think both our experiences have shown that the cheaper components for the most part don't perform to their advertised ratings. My 1st transformer and 1st speed controller for the motor certainly didn't. All in the sake of learning I suppose!
 
ChicagoJohn
Top  #10 Print Post
Posted on 11/03/2015 2:43 PM

Quote


I think both our experiences have shown that the cheaper components for the most part don't perform to their advertised ratings. My 1st transformer and 1st speed controller for the motor certainly didn't. All in the sake of learning I suppose!


Double Ditto on that ! When I was a kid, I think it was Yuban Coffee that at the end of their TV ad invoked John Arbuckle who supposedly said, "You get what you pay for." Guess it didn't sink in in my case ;)
So many beans; so little time....
 
CharcoalRoaster
Top  #11 Print Post
Posted on 11/25/2015 7:18 PM
I just retired an old external hard drive (USB 1!) and want to use its power adapter in a poplite build like yours IKR. Will a swtiching adapter work? 100-240v - 50/60hz 12v - 3.0A
 
IKR
Top  #12 Print Post
Posted on 11/25/2015 9:51 PM

Quote

CharcoalRoaster wrote:

I just retired an old external hard drive (USB 1!) and want to use its power adapter in a poplite build like yours IKR. Will a swtiching adapter work? 100-240v - 50/60hz 12v - 3.0A


CharcoalRoaster

If the diode bridge is taken off the motor, like in my build, at least 20V DC has to go to the motor to achieve stock air flow. Unfortunately, if I'm reading your specs correctly, your switching adapter does not supply enough voltage (12V DC). If the stock diode bridge is still on the motor you can take 24V AC to the bridge but I would go with a transformer that's rated at 5 amps based on my experiences.
Good luck
 
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