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07/22/2019 10:57 PM
Maybe I forgot to add my username to the PP payment.

07/22/2019 9:24 AM
This reminds me to donate too.

07/22/2019 9:23 AM
I think it is Ken.

07/22/2019 2:20 AM
It does not show on the donations list. Is that a manually updated list?

07/21/2019 12:48 PM
Thanks Ken! Great to have you as an HRO member! coffee drink

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Make "CR3" part of TC4 family?
Ok, great thanks. I also found your website info helpful. What is the extra hardware required for fan control? I'll be running a 120v vacuum blower
CharcoalRoaster wrote:

Ok, great thanks. I also found your website info helpful. What is the extra hardware required for fan control? I'll be running a 120v vacuum blower

There is two ways you can do it.

1: The "ZCD + random-fire SSR" approach. You will need a ZCD / "zero-cross detector", and a "random-fire SSR". (Note that random-fire SSR is different than the more common zero-crossing SSR. If it's not specified, it's likely the latter!) This is the way it has commonly been done with the TC4. There is a ZCD made specifically for the TC4. I don't make these, but I believe greencardigan does, or at least has done at some point, and has them on Tindie. The random-fire SSR you could get from digikey, mouser, etc.; they might be harder to find on eBay or other sources, as they are less common than regular SSRs.

2: The "PWM dimmer module" approach. This is how I personally would go about it. You need a PWM dimmer module, which replaces both the ZCD and the random-fire SSR. You can get them on e.g. on Tindie: https://www.tindi...-50hz-60hz

I personally prefer the PWM dimmer module approach, since it separates out all the AC dimming into a self-contained module - I think fewer things can go wrong this way, and it frees up some resources on the Arduino for other things. It is also slightly cheaper, I think, since the PWM dimmer module replaces both the ZCD and the random-fire SSR. But both approaches work well.

For slightly more technical background: To control an AC fan, you can't just turn power on and off very quickly, as you would with a DC fan. Instead, the turning on and off has to be synchronised with the timing of the AC signal. Essentially, you want to switch the power on part-way through each half-sine wave of the AC signal, so you need to know when each wave starts. There is two ways of doing it.

1: With the "ZCD + random-fire SSR" approach, the ZCD devices generates a pulse every time the AC signal crosses zero (hence the name). This is sent to the Arduino, which in turn sends a signal to the random-fire SSR a certain time after receiving the pulse. The random-fire SSR then immediately switches on until the AC crosses zero again, and the cycle repeats. So the ZCD detects the zero-crossing, the Arduino keeps track of the timing, the random-fire SSR switches when told to.

2: With the "PWM dimmer module" approach, the Arduino switches on-and-off a signal very quickly, which is sent to the PWM dimmer module. PWM stands for pulse-width modulation, and refers to this switching on-and-off rapidly; pulse-width means how much of the signal is on and how much is off, which controls signal intensity. The PWM dimmer module detects the zero-crossing of the AC; it reads the PWM signal; and it switches the AC on at the right time. In this approach, the PWM dimmer modules detects zero-cross, keeps track of timing, and switches the AC; the Arduino only outputs the desired fan level as a PWM signal.

If you want even more technical background, an obvious follow-up questions is, "What are zero-crossing SSRs then, and why is none if this an issue for controlling a heating element?". A zero-crossing SSR detects the AC zero-cross itself, and switches on exactly when the AC zero-cross occurs (if it is told to be "on"), and then stays on at least until the next zero-cross occurs. This is because switching AC on and off at other points in time can create various issues if you don't time it right, hence the zero-cross SSR does the timing for you. This is easier, but it means you can only switch your AC load on and off relatively slowly, or with relatively coarse-grained control. And indeed, the standard way the TC4 controls a heating element is by switching them on and off (via the zero-crossing SSR) once a second, leaving the heating on for a specified part of each second. This is OK: The heating element doesn't heat up or cool down much in the span of one second. But for a fan, switching it on for half a second and off for half a second would make for very choppy operation at best, hence something faster is required. With DC a straight PWM signal works, and with AC, chopping off part of each AC half-sine wave is the usual approach (same as an old-fashioned dimmer switch for your ceiling light). Now, the difference between a zero-crossing and random-fire SSR: A zero-crossing SSR switches on only when the AC crosses zero - if the input signal switches from off to on halfway through a half-sine wave, the SSR waits until the next zero-cross before it switches on. A random-fire SSR switches on immediately if the input signal changes from off to on. Hence the random-fire one can be used to time the switching on within each half-sine wave (but it requires you to handle the zero-cross detection and timing externally); but the zero-crossing one can't (but you don't have to worry about zero-cross or timing). And a PWM dimmer module combines the best of both - fine-graind, fast control, but no worrying about zero-cross or timing.
Just to add to what Matthias has said. The "PWM dimmer module" on Tindie is rated for 5A current. That's about 600 Watts on 120V or 1200 Watts on 240V. That should be ok for small vacuum cleaner motors.
The BT139-600 triac used in the Tindie project is rated for 16A.
So 5A limitation come from heatsink only, can be raised with a greater heatsink.
Is there a need for use of an external PID in combination with these boards? If used in conjunction with Artisan/something like it, the boards handle control of the roast profile? Or, are they just data tracking/logging?
If you mean CR3/TC4(+), it can drive a roast from start to end, under your manual control or using a profile. Stacked with an Arduino board, not alone.

If you mean tindie dimmer, is useless by itself, is just a peripheral that execute commands from the "brain".
Thanks for the clarification Renatoa -- I was referring to the CR3/TC4+
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