Announcement

Collapse
No announcement yet.

UPDATED 12/11/2013 - Popper Roasting - Tips, Tricks & Mods

Collapse
This is a sticky topic.
X
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #46
    Originally posted by deegee View Post
    Relatively cheap SCR's ( less than $10 ) will handle up to 4KW. Most claim to be variable from about 10V up to full supply voltage. In reality the ones I have used will output from about 20v to about 230V when connected on a 240V supply, but this is OK.
    Can you tell me the part number of the SCR chip on this? Can you also sketch out the schematic of the unit? I need to probably modify it for 120V AC and the sellers do not supply enough technical data.

    Comment


    • #47
      Originally posted by deegee View Post
      So both Mk1 and Mk3 have been fitted with digital voltmeters. I can now increase the heat more accurately with either of them, and I can get the exact time/ temperature profiles I want.
      Why not add either a dial thermometer or a thermocouple and go by the actual temperature? That's what I plan to do.

      Comment


      • #48
        Originally posted by PacoH View Post
        Why not add either a dial thermometer or a thermocouple and go by the actual temperature? That's what I plan to do.
        Maybe I haven't made it clear in this thread, but all my poppers have thermocouple probes and digital thermometers (see post 32 above)
        and have had them since I first started roasting with poppers.

        The SCR's I use have a part number x4.cn on the PCB, but I don't think you will find them on ebay from that. I cant see any number on the chip.

        If you search within ebay for - SCR motor speed control - you will get a lot of hits. Most of them are for 220V but a few are rated 110-220V. They are a 2000 watt unit with four terminals. Two are marked power in and two are power out. A search for - AC110-220V 2000W SCR Voltage Regulator Dimmer Motor Speed Temperature Controller - will find them.

        The ones I use are rated as 220V 3800 watt and look like the ones in posts #3 & #21. They only have two terminals and the unit is simply inserted in the live wire. in series with the heater coils, but I don't know if they would work on 110V.

        Sorry, but I don't have a schematic for either of these units.

        Comment


        • #49
          Originally posted by deegee View Post
          Maybe I haven't made it clear in this thread, but all my poppers have thermocouple probes and digital thermometers (see post 32 above)
          and have had them since I first started roasting with poppers.
          It's hard to see anything in those tiny thumbnails and clicking on them, I don't see any of what you mention attached to a popper other than one image that shows some kind of narrow probe inserted into the wall of one. It doesn't seem to have a display attached to it. But then why do you need to monitor voltage? You said it changes from unit to unit and from popper to popper and is only a relative quantity. Temperature is a more 'absolute' quantity. It takes everything into consideration. Fan flow, heater current, dimensions of the popper tube, bean density, etc. Temperature's what's important to monitor when you do a profile.

          If you search within ebay for - SCR motor speed control - you will get a lot of hits. Most of them are for 220V but a few are rated 110-220V. They are a 2000 watt unit with four terminals. Two are marked power in and two are power out. A search for - AC110-220V 2000W SCR Voltage Regulator Dimmer Motor Speed Temperature Controller - will find them.

          The ones I use are rated as 220V 3800 watt and look like the ones in posts #3 & #21. They only have two terminals and the unit is simply inserted in the live wire. in series with the heater coils, but I don't know if they would work on 110V.
          Yeah, I know. But since there is zero technical specs available, they are all black boxes to me. If I had the chip's identity I could find out all I need to know about how they would need to be configured. I asked several sellers if they had specs and they said no. The one that does mention 110V, 'AC 110v 220V 2000W SCR Voltage Regulator Dimming Speed control Thermostat motor', then goes and lists the Input Voltage: AC 220V. I asked the guy about this and he swears you can input 110V without modifying the circuit. If that's the case then any of the 220V 3800W units would probably work too. And they may very well work as is, but I'm an engineer so it is very foreign to me to accept a component without having the exact specs in front of me. That's why I ask. And BTW all these units have 2 inputs and 2 outputs.

          Sorry, but I don't have a schematic for either of these units.
          I was hoping you'd draw up a sketch with values. There aren't many components on that board. That way I could reverse engineer the specs of the SCR. Otherwise I have to go on blind faith. Not something any engineer wants to do ever.

          Comment


          • #50
            Originally posted by deegee View Post
            I also tried using a PWM to control the fan speed and it worked. No overheating problems with one of these. BUT - the useable range of adjustment was less than a quarter turn of the knob. Even a small tweak of the knob changed the fan speed a lot.
            G'day deegee...

            Probably only requires a change to the voltage scaling into the PWM control circuit. If you could send me a copy of the circuit being used, or a link to it, I might be able to make a couple of suggestions; should you wish to continue pursuing the option of PWM Control of the fan speed. It's an ideal method to use for this purpose, probably down to about 20% of the fan's nominal full speed...

            Mal.

            Comment


            • #51
              Re PWM

              Originally posted by Dimal View Post
              G'day deegee... Probably only requires a change to the voltage scaling into the PWM control circuit. If you could send me a copy of the circuit being used, or a link to it, I might be able to make a couple of suggestions; should you wish to continue pursuing the option of PWM Control of the fan speed. It's an ideal method to use for this purpose, probably down to about 20% of the fan's nominal full speed...Mal.
              G'day Mal. You're probably right about that. The output is controlled by a 10K pot. Over the full range of the pot, it takes the fan from full speed down to almost stalled. This is much more reduction than I need, so only a quarter of a turn of the knob is usable in practice.

              I only need to reduce the speed to about 60% at most, for my application. Maybe if I measure the resistance of the original pot over the "useable section" then replace it with a pot about that value, I may get the reduction that I need, but spread over a full turn of the knob. Your thoughts ???

              I don't have a circuit, or a link to one, and some of the components on the board have no markings whatsoever, so their values are a mystery. I suspect that trying to draw a circuit would be an exercise in frustration. At this time I'm more inclined to take the 'seat of the pants' approach.

              Cheers, deegee.

              Comment


              • #52
                Hello Paco,

                I thought that there were more pics in this thread showing a popper with the thermocouple probe and digital thermometer, but they must be in other threads. Sorry, I should rectify that.

                "Temperature's what's important to monitor when you do a profile"

                Yes it is - but I like to establish a pattern for my roasts based on regular voltage increases to achieve the temp profile that I want.
                That way I don't have watch the temp every second of the roast, with my hand poised over the knob, making adjustments on the fly.
                I have a pattern for my preferred profile for most beans, but I also have one longer slower roasts, & another for shorter faster roasts.
                Using these, I choose my start voltage and increase it at one minute intervals to get the required profile.
                That's the main reason why I added the voltmeters.

                "I was hoping you'd draw up a sketch with values"

                I would, but some components have no markings, & others would have to be removed from the board to be able to read them.
                These things are as cheap as chips. If I was in your situation I would buy one and try it on 120V. If they work - that's great, if not, you can dismantle and measure values, then maybe modify it if needed. If it's a write-off, its only a few bucks.

                One of them from ebay seller "sitedv88" Item SKU: 14_S000114008967 specifies :- Voltage 110 - 220v Voltage control 50 - 220v.

                Comment


                • #53
                  Originally posted by deegee View Post
                  I only need to reduce the speed to about 60% at most, for my application. Maybe if I measure the resistance of the original pot over the "useable section" then replace it with a pot about that value, I may get the reduction that I need, but spread over a full turn of the knob. Your thoughts ???
                  Yes mate...

                  That's the general idea. Not all that complicated....

                  Mal.

                  Comment


                  • #54
                    Thanks Mal, I'll give it a try, but probably not 'til later this week.

                    Cheers, Deegee.

                    Comment


                    • #55
                      Here's a good article for some to read

                      http://ineedcoffee.com/popper-crop-c...pcorn-poppers/

                      Comment


                      • #56
                        Here's an update. I found an eBay link deleted per http://coffeesnobs.com.au/general-ne...icy-rules.html AC 110v 220V 2000W SCR Voltage Regulator on eBay for just USD$5.00 but I ended up getting the much-recommended Harbor Freight Router Speed Control instead. I figure the time and money I would have spent putting the cheap SCR board in a box would have cost me more than this reasonably priced, self-contained unit. It was on sale for $19.99 and with the 20% OFF coupon it cost just USD$17.40 with the tax. And it has a 90-day no-questions-asked return policy on it. You don't get anything close to that on eBay. There are many posts on forums about using this little workhorse for coffee roasting, beer brew-kettle controller, and many use it for controlling stage lighting. The last 2 uses require adding a hefty heatsink to the metal back-plate, and even for coffee roasting that is advisable. It gets hot to the touch--3 seconds max finger contact--so I will add a heatsink to prolong the life of the SCR. It is designed for the short bursts that you'd use for a router, not extended minutes at a time like you'd use for coffee roasting. So far it works great. I have drastically reduced the temperature of an 1100W popper so I can get long roast times. I put the switch on direct power until the first crack so this doesn't tax the SCR at all, and then switch over to variable for the rest of the roast period.

                        I still have to rewire the fan so I can power it separately from a DC supply. I thought of separating out the motor rectifier circuit and achieving a constant 30V using zener diodes in series to keep it down to one cord, but it won't work with an SCR because it varies the duty cycle, not the amplitude. I have a Variac buried in a mountain of boxes and that would work, but the sheer weight and bulk of it defeats the purpose. A separate power supply with a jack would still be quite compact.
                        Last edited by Javaphile; 25th September 2014, 02:29 PM. Reason: eBay link(s) removed

                        Comment


                        • #57
                          Thanks for that link. It is another reference to add to my collection. It seems that all those poppers are discontinued, and about half of them are the screen-on-the-bottom type which require modification. I started a thread on currently available poppers that met the spiral-vent criterion, years ago at Sweet Maria's: List of Current Air Popcorn Poppers for Coffee Roasting and only recently visited it since I never received email notifications of posts. It has gotten a life of its own and there are a number of poppers users recommend along with tips on various mods, some dangerous. The only 2 that are currently available at a REASONABLE price are:

                          West Bend 82416 Air Crazy 3.5 Quart Corn Popper






                          This is probably the best choice in a popper because it is widely available at a deep discount off the $29.99 MSRP and is widely used for coffee roasting.

                          and:

                          Kitchen Gourmet model B-32B [1200W] from Walgreen's



                          Cannot find online. This is the one I got Dec. 30, 2010. $7.99 ($9.99) on sale. $8.77 total. They seem to be only available during the Christmas season.

                          Comment


                          • #58
                            Hi All,

                            Wanted to share some data around some poppers I have been testing. Since I am new to roasting with a Popper (couple of weeks now), thought it would be good to share what i have done so other people can learn from my experience.

                            Today i am showing the difference of two popcorn makers:
                            1. Benzer Popcorn Maker - 1200w, 50Hz, 230-240V, Model: 8806 (Brought new at Victoria's Basement) -$30-40 new
                            2. Breville Crazy Popper - 1100w-1200w, 50Hz, 230-240V, Model: PCM40 (Brought second hand at Vinnies) - $10.

                            Modifications
                            1. Benzer Popcorn Maker - Holes drilled in base, side, top (approx. 30-35 drill holes about 3-4mm. Majority on base and lower half and 13 on the top). Since I have had this longer, i know it runs hotter and modified it to give more airflow.
                            2. Breville Crazy Popper - None

                            Both popcorn makers i have removed the clear plastic lid.

                            Pictures attached
                            Click image for larger version

Name:	IMG_3742.jpg
Views:	1
Size:	143.5 KB
ID:	737944Click image for larger version

Name:	IMG_3744.jpg
Views:	1
Size:	312.6 KB
ID:	737945
                            Click image for larger version

Name:	IMG_3745.jpg
Views:	1
Size:	275.2 KB
ID:	737946Click image for larger version

Name:	IMG_3746.jpg
Views:	1
Size:	234.5 KB
ID:	737947Click image for larger version

Name:	IMG_3748.jpg
Views:	1
Size:	285.0 KB
ID:	737948

                            So I have been roasting a single origin - Guatemala La Pacaya Typica

                            So without beans this is the sort of temp celcius that i was getting after 2 mins (its only a handheld thermometer as i really only wanted to know how hot/fast the popcorn maker was getting). So apologies if i havent got a fancy graph and its not 100% accurate

                            Ambient temp: 21 degrees

                            Time (min:sec) Benzer Breville
                            00:30 123 C 128 C
                            01:00 150 C 139 C
                            01:30 182 C 140 C
                            02:00 193 C 150 C
                            Result 198 C 165 C
                            So straight away you can see the Benzer heats up a lot faster.

                            So how did it go when i roasted some beans


                            Time
                            (min:sec)
                            Benzer (60g Beans) Breville (60g Beans) Breville (80g Beans)
                            00:30 93 C 80 C . (didnt record)
                            01:00 145 C 140 C . (didnt record)
                            01:30 160 C 168 C . (didnt record)
                            02:00 176 C 183 C . (didnt record)
                            02:30 190 C 194 C . (didnt record)
                            03:00 196 C 193 C . (didnt record)
                            03:30 199 C

                            1st Crack @ 03:10
                            201 C

                            1st Crack @ 03:20
                            1st Crack @ 03:45
                            04:00 216 C 211 C . (didnt record)
                            04:30 . (didnt record) 213 C . (didnt record)
                            05:00 . (didnt record) . (didnt record) . (didnt record)
                            05:30 2nd Crack @ 05:30
                            Stopped Roasting
                            . (didnt record) . (didnt record)
                            06:00 . (didnt record) . (didnt record)
                            06:30 . (didnt record) . (didnt record)
                            07:00 . (didnt record) . (didnt record)
                            07:30 . (didnt record) . (didnt record)
                            08:00 . (didnt record) . (didnt record)
                            08:30 . (didnt record) 2nd Crack @ 08:30
                            Stopped Roasting
                            09:00 . (didnt record)
                            09:30 . (didnt record)
                            10:00 . (didnt record)
                            10:30 2nd Crack @ 10:15
                            Stopped Roasting
                            So how did they look and smell.
                            • Benzer (60g) - smell was a little burnt but same colour as other beans. Lost 10g of weight post roast
                            • Breville (60g) - no burnt smell from beans. Looked clean and same colour as other beans. Lost 10g of weight post roast.
                            • Breville (80g) - no burnt smell from beans. Looked clean and same colour as other beans. Lost 14g of weight post roast


                            So since i have only roasted, i will need to let you know how they taste in about a week.
                            From previous roasts with the Benzer popper it was really nice, but had bitterness through the shot. Much easier with Milk.

                            I suspect the Breville with a longer roasting time and a good break between 1st and 2nd crack will be much cleaner and not have bitterness through it.

                            Recommendation:
                            Well its a little early to say, but i think the Breville crazy popper is much better. Longer roast and no burnt smell from bean.
                            I will probably make a call and say the 60g will be the best as the roast was the longest.


                            Well i will let you know how it tastes in a week.


                            Keep popping on all - Loads of fun :-)

                            Comment


                            • #59
                              Just wanted to share an update.

                              Since I had been roasting with the benzer a few weeks I thought that was amazing roasted coffee.

                              Boy was I wrong. As soon as I opened up and tasted both the breville batches I was blown away. So much nicer.

                              So breville popper wins hands down.

                              Now on to roasting a few more origins and then into blending them. My world is so much better now :-)

                              Comment

                              Working...
                              X