Alternative popper mod suggestions

[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.

[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

[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.

[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.

[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.

[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.

[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

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?

[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.

[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.

[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.

[emckissock]

Re: Alternative popper mod suggestions

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

Actually, I hadnt thought of that but yes that is a good idea.
I just thought that since I have one, it would be a shame not to put it to good use.

[emckissock]

Re: Alternative popper mod suggestions

Since the weather has improved somewhat here in Melbourne and I finished work early, that gave me the chance to sneak into the garage and play with my big knob (see above for picture).

I did a small roast of 95g of Gambella Sundried full power to first crack at 3:40 (unusually fast for my popper), then down to 800W for a couple mins, back to 900W until 8min 30, then 1050W until I think I heard a snap of second crack at 9min 30 and pulled the roast - very pale CS6/7 so may have misheard. Unfortunately my spare thermocouple was in use for another task so dont know about temps

I have to say Im pleasantly surprised as I was worried that lower fan speed would mean the beans were in contact with the hot metal more than they should be and it might not provide the control I wanted.
Definitely warrants further testing with a temp sensor installed to keep a gradual ramp up of bean mass temp 1st to 2nd crack.

[Dimal]

Re: Alternative popper mod suggestions

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).

Sounds like you may already know how to overcome this incorrect supply issue but just in case you end up keeping this controller, there is a simple mod to allow it to drive the SSR. You need to ensure that the Input requirements for the SSR are met and not exceeded of course....

Remove the cover from the controller and locate the +ve feed to the existing Output Relay Coil. Being very careful and with an appropriate DMM, measure the supply voltage to this relay when it is operated. Knowing this information, you can now scale the output voltage to suit the SSR via the use of a Voltage Divider that can be accommodated within the controller case. If you want to ensure absolute isolation of the Output Voltage, very cheap Opto-Couplers are easily acquired and could be inserted between the Relay +ve and Ground. The Output from the Opto-Coupler can then be used to drive the SSR.

Most likely though, the Relay supply is already isolated in this way and the need for an Opto-Coupler is unnecessary. Never hurts to have more than one iron in the fire, as they say...

Cheers mate,
Mal.

[emckissock]

Re: Alternative popper mod suggestions

Sounds like you may already know how to overcome this incorrect supply issue but just in case you end up keeping this controller, there is a simple mod to allow it to drive the SSR. You need to ensure that the Input requirements for the SSR are met and not exceeded of course....

Hadnt even thought about that, but yes it is obvious now you mention it. I had considered a much simpler fix - use the internal relay to drive a small DC plug pack that then drives an SSR, not at all elegant, but dead simple and would save opening up a PID that might still be requested back (though it has been months now so it is highly unlikely).