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02/27/2021 9:50 AM
Questions are best asked in the forum. The posts will last longer, and will be seen the most by members. After a few more posts in the Shoutbox, the post you made will no longer be seen.... maybe you could also introduce yourself and share a little.

02/27/2021 9:29 AM
I'm looking to hire someone to teach/help me to find the best roast profile for the 3 types of coffee that grow on my farm in nicaragua. I live in LA, but but could go anywhere in so cal with my Behmor for a roasting lesson. Please contact me if you're in

02/17/2021 7:20 PM
When your wife thinks 30 grams for a 6 cup setting is strong, you learn to drink muddy water when you are making coffee for both of you.

02/17/2021 8:32 AM
I use a rule of thumb of 60 grams per liter. 8 cups (1 liter, 32 oz) = 60 grams, 6 cups (3/4 liter, 24 oz) = 45 grams. 10 cups = 75 grams 12 cups = 90 grams

02/17/2021 1:47 AM
OldMan41, depends what is "a pot"... usually is more accurate to specify the brew ratio, instead grams of coffee. The most usual is 1:15, thus 40 grams for 600 ml of water. If the 100 grams are for one liter pot, then we are talking about 1:10 ratio.

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Nostalgia Hot Air Popcorn Popper Build A,B, C
Don't use a PID to control temperature. It switches too slow. Buy a thermocouple probe and meter. Probe must be in bean mass about 1/8" above bottom of roast chamber. I'd modify the popper in the following order. Option A and B uses fan to control temperature. Option A: Wire 15 ohm element to On/Off switch. Control the 100 ohm element and fan/diode bridge with a light dimmer (Westek 6077B 200-Watt Manual Dimmer Replacement Kit $6). Option B: Remove 100 ohm element from fan circuit. Control fan/diode bridge with light dimmer and a 115/44VAC transformer (Hammond Mfg 166J44 $40). Option C: Connect a PWM (WHDTS Adjustable Signal Generator $13) to the Gate of a MOSFET (IRFZ44N), Source of MOSFET to ground, Drain of MOSFET to minus side of solid state relay (Inkbird Solid State Relay 40DA $15). Connect +VDC to plus side of solid state relay. Switch 115VAC through the solid state relay and connect to 15 ohm element in popper. Control heat using the duty cycle of PWM. At this point you have spent about $200 which makes the Fresh Roast look like a pretty good option. I roast 70 grams in this popper and get pretty good results.
Edited by ocojo on 02/10/2021 3:38 PM
Agree about "Don't use a PID", but not about the reasons.

Depends on PID... most models I know comes with a relay output setting for on-off, i.e. 20 seconds cycle.
If you switch them to SSR output, the cycle time is reduced to 2 seconds, which is exactly what you need for 1% resolution and 50 Hz mains.

What is wrong with using a PID though... the output PWM modulation happens only in a narrow band related to the P term value. Until that band is reached the output is 100%, which can led to roast damages.
For example if you have a set value of 150 C, and a P term value of 30 (as comes by factory default the popular REX C100 PID), the proportional band is 100%/30 = 3 degrees, so until you reach 150 - 3 = 147 C degrees, the power is 100%, then start to modulate and reduce to the value required to maintain the set value of 150C

You need a high class PID controller, priced even triple times than a full TC4 setup, to have this issue overcome, i.e. featuring a separate setting to limit the output value during the ramp toward set value.

There is another even lower priced option to the above listed, the $15-20 SCR regulator with digital control and display, you can buy from Amazon, ebay or other chinese sources, similar to the below link:
Edited by renatoa on 02/12/2021 1:45 AM
Motor controls are an option but the comment sections aren't overloaded with positive reviews. The PID I was using was turning on and off in an appropriate manner but the measured temp would still drop 10 degrees before ramping back up again. I thought that was a thermal mass type problem so I screwed around with adding metal to the chamber (pennies in a false bottom, wrapping some steel sheet around the sides) but that only improved the temp swing marginally. I have found that the PWM with a MOSFET gives very tight temp control. The PID still makes a handy thermocouple reader so it wasn't a complete throwaway.
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