Alternative popper mod suggestions

[conan.obrien]

Re: Alternative popper mod suggestions

Along with drilling the popper base, this has stretched 1st crack from 3-4 minutes to about 6-7 minutes.

Ive been toying with drilling holes in the base too.
Im thinking about how to do it to stimulate bottom to top bean curculation as well airflow. I might drill holes all over the centre of the base to increase the the amount of beans rising in the centre (seems to be the natural circulation pattern for the beans when they are dry and light but this might get circulation going earlier). The other option is to drill holes all over one half of the base and get the top to bottom circlation going that way (similar to the effect of tilting the popper, so it would work well together with a tilt).

Interesting what you seaid about the tilt and jiggle technique delaying first crack. I found vigorous stirring with a stick slowed down the cracking once it had started. I guess this moderates the heat by increasing airflow but as well as that makes sure the beans are all the same temperature so you dont have some of the beans getting to 1crack before the others.

[conan.obrien]

Re: Alternative popper mod suggestions

Incidentally, how do you empty the popper once it is installed in the microwave?

The bean chamber just slides out the top. When the roaster is complete Ill be able to turn off the heat and leave the fan running to cool the beans in the chamber but for the couple of roasts Ive done Ive used a leather glove to lift out the hot chamber.

Who me?, I like your power control setup. A big knob like that would give you plenty of room to mark preferred power levels.

[mtee]

Re: Alternative popper mod suggestions

As well as making technical mods, you can slow the roast down by using a few simple little techniques.

I increased the quantity of beans to about 115-120g depending on which popper Im using.

On start up, this amount of beans wont move on their own, so I tilt and jiggle the popper to get the beans circulating. I used to do it for a minute ot two, just until the beans would move on their own, but found doing it for longer (3-4 minutes) slowed down the first crack significantly. I then place the popper on an angle to keep the beans moving and steadily make it more upright as 1st crack approaches.

Along with drilling the popper base, this has stretched 1st crack from 3-4 minutes to about 6-7 minutes.

Id be fiddling with fans and heating elements too, if I knew how, but Ill leave that to technically competent.

[emckissock]

Re: Alternative popper mod suggestions

I ended up going with a PID temperature control unit running a seperate 25A solid state relay. Turned out to be a similar price to the triac dimmers mentioned above. I went fishing in the bay of e and got the lot for $42 including postage from hong kong. Cant wait till it arrives.
Make sure you get a PID unit  that gives a DC output for controling an SSR instead of one with a mechanical relay built in that will wear out and break with the fast switching youll need.

At that price, your PID will not have ramp/soak functions. All you will get is a single set point and it may or may not support different thermocouple types, but in practice, most folks here use K-type anyway. I ordered a PID from the USofA fleabay (for my Gaggia classic) as I got it cheaper there than Aus and it still came from Hong Kong anyway. I clearly specified one that handles an SSR, but they still sent me the wrong one with an internal relay - fixed the problem quickly though and I still have the incorrect relay even though I tried to get them to take it back.
Another issue with the mechanical relay PIDs is that they are often only rated up to 3A (or 720W at 240V).

Anyway, the thing I need help with is where to put the thermocouple. Do I put it in the beans and continually adjust the temperature manually, giving me steps instead of a ramp. (or maybe there is a ramp function in the pid unit?)
The other option is to put the thermocouple in the hot air stream just under the bean chamber. This would give me good repeatable control of the heat regardless of ambient temperature and Id probably only have to adjust the temperature setting a couple of times in the roast. The disadvantage is Id probably have to buy another thermometer to go in the bean mass.

Im sure others with more experience will chime in soon enough, but you will not get an accurate bean mass temperature in a fluidised bed, the best you can hope for is something between bean and air temp. This will not matter in practice once you have several previous roasts to refer back to, but makes it hard at first.

I am just about to use my PID with internal relay and a K-type thermocouple to measure temps in my triac controlled popper. I plan on inserting it so the tip is about 1-2cm above the base of the roasting chamber and as close to the centre as possible, this should get me reasonably close to bean mass temp, but I dont know how it will interfere with the movement of the beans.

Has anybody tried either of these? Ive searched this site and can only find pids used for heat guns and coffee machines, not poppers.

Ive definitely seen something on the net about adding a PID to a popper, cant remember where though. I am pretty sure it was a much more expensive set-up with multi step ramp/soak.
I really dont know that a simple PID will give decent control as the heater is either full on or full off and the proportional bit comes from the on/off times, but it will be interesting to see how it works out.

I went the triac route as it was free (apart from a couple of hours and that was play/education).

Im considering options for airflow management and may go for a hairdryer or computer fan as I happen to have both. Of course I could bring out the big guns and use a 1200w vac motor, but then heating would need to be increased too and that kinda defeats the purpose of a small roaster. Im shooting for a 200g maximum batch size with 3-4 mins between first and second crack. Once I get that Ill be happy.


Incidentally, how do you empty the popper once it is installed in the microwave?

[conan.obrien]

Re: Alternative popper mod suggestions

After looking at a few options like the triac for power control I ended up going with a PID temperature control unit running a seperate 25A solid state relay. Turned out to be a similar price to the triac dimmers mentioned above. I went fishing in the bay of e and got the lot for $42 including postage from hong kong. Cant wait till it arrives.
Make sure you get a PID unit that gives a DC output for controling an SSR instead of one with a mechanical relay built in that will wear out and break with the fast switching youll need.

Ive discarded the popper chasis and Ive put the guts of it in the case from an old microwave with the bean chamber poking out through a hole in the top. This microwave popcorn chimera bulky but as well as plenty of room for mods it gives me a work surface on top and a bean storage cupboard in the bit where the food used to cook. I tried using the microwave power control to moderate the heat but it would turn the power off for 8 seconds every 30 seconds on medium high so that was the end of that. :-/

Anyway, the thing I need help with is where to put the thermocouple. Do I put it in the beans and continually adjust the temperature manually, giving me steps instead of a ramp. (or maybe there is a ramp function in the pid unit?)
The other option is to put the thermocouple in the hot air stream just under the bean chamber. This would give me good repeatable control of the heat regardless of ambient temperature and Id probably only have to adjust the temperature setting a couple of times in the roast. The disadvantage is Id probably have to buy another thermometer to go in the bean mass.

Has anybody tried either of these? Ive searched this site and can only find pids used for heat guns and coffee machines, not poppers.
Oh and before anybody tells me Im wasting my time doing this on a popper, I want the small batch size.

[emckissock]

Re: Alternative popper mod suggestions

A couple of photos of my lightly modded popper. Note that the power adjustment even has correct power level markings.

Still to test it out, just need to wait for the rain to stop.

[emckissock]

Re: Alternative popper mod suggestions

Took my popper apart this afternoon. It wasnt easy getting the mains cable out due to the tight cable strain relief, but with a fine screwdriver and suitable application of force, all was revealed.

I tested one of the triac power controllers I have on the popper as it stands and it works fine for power control. Nice thing is that it will just fit in the case below the main chamber, directly in the inlet airflow and has a heatsink already on the circuit board. I doubt it will be of much use to drop fan speed and heat at the same time, so I need to maintain fan speed and adjust heat output, or separately control fan speed.

I havent unscrewed the fan from the body yet, but the wiring looks identical to that posted here:
http://coffeesnobs.com.au/YaBB.pl?action=downloadfile;file=TiffanyPopperSche matic.pdf

Colours even match. So, it doesnt look like I can just splice in power control for the heater as the two elements are almost certainly in series.
Time to go hunting for a spare transformer, or perhaps find a suitably rated switchmode power supply for the fan and leave it running full tilt all the time.

[Dimal]

Re: Alternative popper mod suggestions

Mal, I tried to find info from commercial sources but no luck. And with the info in this and a couple of other threads around the place Id be more willing next time to have a look at making one up.

Good idea "hazbean"... 8-)

Its a relatively simple thing to do but requires special attention paid to the 240V AC side of things to maintain safety standards. Lots of info about this can be found too or ask a sparky to pass his/her critical eye over it before powering up. "Silicon Chip" is an excellent resource for this sort of info....

Cheers mate,
Mal.

[hazbean]

Re: Alternative popper mod suggestions

Interesting link, Bill, thanks. They seem better constructed than the one I got, at least with regard to integration of the heat sink.

Mal, I tried to find info from commercial sources but no luck. And with the info in this and a couple of other threads around the place Id be more willing next time to have a look at making one up.

[Bill]

Re: Alternative popper mod suggestions

Earlier this year I needed a 1000W dimmer for heatimg control on my Gene. The only Aus one I could find was $160. So I imported a Varilight dimmer from the UK.

Yep, they seem pretty expensive in Aus. My 2000W dimmer was only £22 from the UK. Works well, and never had any problems with it.

http://www.quasarelectronics.com/ci0013-230vac-light-dimmer-module-range-250-4000w.htm

[Dimal]

Re: Alternative popper mod suggestions

Large capacity Dimmers (for resistive loads) are available here in Oz, mostly for commercial lighting applications and can be obtained from commercial/industrial electrical wholesalers who supply licensed electrical contractors. One example I can think of is Theatre Lighting.... Building your own would still be the most economical way to do it though and not very difficult for anyone who possesses basic electrical soldering skills....

Mal.

[hazbean]

Re: Alternative popper mod suggestions

Just a note re Bills post above (#27) about dimmers. Earlier this year I needed a 1000W dimmer for heatimg control on my Gene. The only Aus one I could find was $160. So I imported a Varilight dimmer from the UK. This played up at first, but an email exchange with the engineers at Varilight sorted out how to fix it. Basically the heatsinking needed attention. What I did was disassemble it, apply plenty of heatsink compound at appropriate places, especially the contact area between the triac and the supplied heatsinking; then added additional heatsinking, comprising aluminium sheet bent into an S-shape and with finned PC heatsink blocks attached. I left room in my enclosure for a fan, but that hasnt been needed, it has worked fine ever since. With the additional heatsink properly installed, the dimmer easily handles the 1200W of the Gene. Nonetheless, had I known when I bought it that they had a 1500W version for not much more, I may well have bought it (in that design, the triac is separated out from the other components). Anyway, clearly heatsink design is a key aspect of these higher power dimmers (that might be why the Aus designed one is a lot more expensive).

[maheel]

Re: Alternative popper mod suggestions

Ok this is the diagram (simple picture) traic based power controller

the 1st one i built did not have the 1M resistor and was not 0 - 100% linear. it did range from around 140v to 240v control i was then advised to add the 1M and it should help. I am not sure if i built and tested it with the 1M res

The BTA26-600B TRIAC could then handle 26 amps, way more than what i wanted at about 2500w. so you could choose a lower amp triac.



the BTA26-600B TRIAC (or any triac) would have to be mounted to a heat sink or it would quickly blow blue smoke... i used a PC heatsink and fan. You would of course also need to earth it correctly and safely. no earth is shown !! but needed !!

Isolated triacs are very important as some are not !!! and make the heatsink live !!!!

there is a 50page thread about power controllers on "homedistiller.org" where more information can be seen on this diagram at about page 30..... other ideas are in the thread

other smarter than me people here might have some input  

disclaimer, this post is for information only, anyone attempting to build this should consider the risks. no responsibility taken by me or anyone

[Bill]

Re: Alternative popper mod suggestions

i have never seen a 2000w light dimmer (actually PMed Bill about it), and the normal ones only run about 600w i thought.

I wasnt able to find such a high power one either, within Australia, but was able to source one online from an electronics supplier in the UK. Can get ones up to 4000W from the same supplier.

[conan.obrien]

Re: Alternative popper mod suggestions

Looks good Maheel, Id like to see a diagram if you feel like putting one up. I might do that when I do the final version of my popper.
What do I need to take apart to find triacs that can handle power?

For now Im gonna crack that power control nut with a beautiful old sledgehammer in the form of an big old variac my grandfather gave me. I just have to check the current rating on it when I get it out of storage. (btw I saw a 5A variac on a popular auction site for pickup in footscray if anyone wants big-is-beautiful power control).

Another cheap option: I stumbled accross infinite switches while researching phase angle control. They control the current with a bimetalic strip inside the switch that gets hot when the current flows. They are in electric stoves like you see in skips every other day, prob is you need to get exactly the right current rating because you cant change them easily by just adding resistors.