Zizzle's Brewbot

[Jye]

Only 5 hop additions... thats barely enough to brew a wheaty

Very nice work :beerbang:

 

[Zizzle]

Oops, should work again now Wally.

Jye: I ran out of pipe to make the hop holders. I think should hold at least 40g each tho.

 

[Jye]

I think should hold at least 40g each tho.

So much to learn

 

[yardy]

bloody amazing zizzle, 2 years from now i can see a production line churning out brewbots for delivery nationwide. i'll knock up the production line for a heavily discounted brewbot if you like ;0 lol Cheers

 

[bonj]

Sweet video, mate.

I'd love to see the bot in action.

 

[Zizzle]

Well anytime your down this way give me a yell. Otherwise will do a brew day in the next couple of months.

 

[winkle]

It needs some black pin-striping and a twin over head foxtail.
Serious bit of kit mate.

 

[bonj]

Well anytime your down this way give me a yell. Otherwise will do a brew day in the next couple of months.

Will do. A brew day sounds like a plan too.

 

[Zizzle]

Recent activity:

Upgraded to a wider kettle:

Move old kettle to new role as HLT. Redid the level probes:

Solenoid mounted on the side:

Zero to mash in under 15 minutes:

 

[Zizzle]

Brewbot now has a brother. One of the local forum members has been busy working away with a little help.

Although heavily influenced by the orginal, brewbot2 has it's own customisations. Similarly built from largely scrounged and improvised parts.
Aimed at a more permanent installation, it had it's inaugural run with success last night.

Gravity fed, 3 tier setup, attached to a wall.

The brains, hardware very similar to the original.

Some niceties are afforded by the permanent setup, such as being connected directly to a dedicated 25amp circuit.

March pump and windscreen wiper actuated ball valve.

HLT in the sky and it's wiper actuated ball valve.

Brewbot2 may actually beat the orginal to having a HERMs integrated.

Please form an orderly queue those wanting to place an order for Brewbot3

 

[Zizzle]

Got busy motorising my Barley Crusher using a garage door opener fished out of the bin (thanks Brad!). A nice little 200w 240v DC motor with worm drive and other reduction gears.

Then a quick'n'ugly MDF box over the lot to keep little fingers out of the high voltage areas & gears.

One less thing to have to stuff around with on brew day.

 

[Pumpy]

Zizzle you are a sheer mechanical wizard !!!!!

Pumpy

 

[Zizzle]

Not content to have a brewbot that actually worked I had to go and want it to be more compact. I also wanted to get rid off all brass & copper in contact with the wort. So part of the reorg is to minimize the number of fittings to replace.

Cut the frame in half and upended it...

The HLT now gravity feeds the MLT so the old actuated brass gates valves are gone, and a new ball valve mechanism...

Now just waiting for some more stainless steel bits to show up... brass be gone...

 

[sqyre]

I couldnt help think of you today Z-man... and no i wasnt interfering with myself in the shower... <_<

My work chucked out thier old massive photocopier.. so i grabed it... why? i dont know...
But when i got home i plugged it in and started copying stuff (including my bum) untill i got bored...
Then as most bored red blooded Aussies with an insatiable curiousity do... i grabbed my philips head screwdriver and went to town in demolision mode...

I was rather hoping i would find a nice big motor with a half decent reduction drive on it to use for my Grain Mill but no luck so far..
However... i did stumble across a bunch of small motors with frigin major reduction drives...
24v -1.85 RPM

They are all plastic but I reckon they might be alright for turn taps on and off..

Sqyre...

 

[Zizzle]

Hell yeah, lets get that stairway automated!

 

[sqyre]

Not sure if i want "The Stairway" being assimilated by the Borg just yet...

i have been in the shed stripping the photocopier down some more looking for goodies and i found a decent sized 20:1 reduction gearbox..
So i've been working on modifying that to hopefully power my grain mill...
its got plastic gears but hopefully the strain on it wont be too harsh...

also if you want any bits and pieces, like small gears, cogs,pullies etc. there are heaps in this copier you can have..
there also a heap of small electric clutches if you have a use for them, as well as a heap of other thing-a-me-jigs...

Sqyre...

 

[Zizzle]

New shiny toys:

Compared to the old one:

So no more hot acidic wort sitting in copper & brass for hours at a time.

 

[alexbrand]

New shiny toys: [...]

Zizzle,

don't you have any problems with caramelizing the wort's sugar on the heating coils at boiling time?


Alex

 

[afromaiko]

New shiny toys:

So no more hot acidic wort sitting in copper & brass for hours at a time.

Where did get the stainless pick up tube and fitting from? I'm going to add a pick up tube, but everything else is stainless so I wanted to steer clear off copper and brass too.

 

[Zizzle]

don't you have any problems with caramelizing the wort's sugar on the heating coils at boiling time?

I've had the problem occur once. It was my first go at a wheat beer. So maybe something to do with the wheat, I don't know.

Since then I have modified the hardware so that all the elements are driven via triacs so that I can vary the duty cycle in software. For the last 6 or so brews (including a successful wheat beer) I have been driving the elements at 85% duty cycle. 2 x 2200w x 0.85 = 3740w. There is usually some white gunk on the elements after a boil, but it wipes right off and doesn't taste caramelised at all.

New stainless bling is from beerbelly.

 

[Martin]

Hi Zizzle, I've loved reading this topic

I've been wondering about a few things: how does the brewbot prevent dough-balls when mashing in? Is it a simple underlet, and does the brewbot stir the mash? If no stirring, are temperature gradients in the mash a problem? Thanks!

 

[Zizzle]

I usually just remember to give the mash a stir, but if I'm not around or forget I'm not too worried. I have the code setup to give a short recirc every few minutes.

But an automated mash stirrer is in the works. Stay tuned.

 

[chovain]

Hey Zizzle,

I dream of putting together a setup like this one day. I want to start out with some microcontrolled power switching, and I have a couple of technical questions about your triac setup:
* I assume you connect the opto to the triac via about a 340R? (Based on Vpeak of 340V)
* What power rating are your resistors?
* What frequency do you switch at for your power control?
* How have you connected the hot-side of the triacs to your high-current wiring? I'm assuming you don't run 10A through vero tracks .
* Have you ever toyed with voltage control (i.e. only partially opening the triac) instead of duty cycling?
* Any idea where you got your power triacs? Jaycar have a terrible range, and people like Farnell are just plain expensive.

 

[mesa]

* What frequency do you switch at for your power control?

A while back I was running an electric boiler with a single kettle element switched by a sawtooth oscillator and comparator at about 0.5Hz (i.e. 2 seconds). I guess I assumed that with the huge thermal mass of 20+L of wort and relatively low thermal resistivity between the element and the wort that there wouldn't be particularly large variation in the temperature of the element. Then again I have no idea how hot the element gets relative to the wort or what effect the formation of bubbles has on the thermal resistivity.

I think what people usually do is use the mains power itself as a reference oscillator. so it would be operating at 50Hz (or kind of 100Hz since you could do the comparision on both half cycles)

I eventually stopped using the switching running the element at full power instead (not enough insulation on the kettle to run at lower power). Then I decided kettle elements at full power scorch the wort too much and switched to a nice gas system with a thick bottomed pot.

* Have you ever toyed with voltage control (i.e. only partially opening the triac) instead of duty cycling?

I don't think a triac can be partly opened (if I remember what a triac is correctly) and if you did have some sort of power FET that could be partly opened, it would dissipate huge amounts on energy in the FET (necessitating huge heat sinking and wasted power)

 

[chovain]

* Any idea where you got your power triacs? Jaycar have a terrible range, and people like Farnell are just plain expensive.

Oh, wait - I just found Jaycar's 15A triac...

 

[chovain]

A while back I was running an electric boiler with a single kettle element switched by a sawtooth oscillator and comparator at about 0.5Hz (i.e. 2 seconds). [...]
I think what people usually do is use the mains power itself as a reference oscillator. so it would be operating at 50Hz (or kind of 100Hz since you could do the comparision on both half cycles)

I suppose as long as I don't run faster than 100, it'll work. Thinking aloud here: One factor I suppose I should consider, is how fine control do I want? Since the Triac will latch until the next zero crossing, the on-off cycles can be modified only by multiples of 10ms. To keep the PWM generation simple, I probably want to pick a power-resolution that I'm happy with, and go for a fixed frequency based it on that. If I want to be able to tweak by 10% granularity -> 10Hz; 1% granularity -> 1Hz.

I don't think a triac can be partly opened (if I remember what a triac is correctly) and if you did have some sort of power FET that could be partly opened, it would dissipate huge amounts on energy in the FET (necessitating huge heat sinking and wasted power)

You're right. I was a bit confused (never used triacs before, either).

 

[Doogiechap]

I suppose as long as I don't run faster than 100, it'll work. Thinking aloud here: One factor I suppose I should consider, is how fine control do I want? Since the Triac will latch until the next zero crossing, the on-off cycles can be modified only by multiples of 10ms. To keep the PWM generation simple, I probably want to pick a power-resolution that I'm happy with, and go for a fixed frequency based it on that. If I want to be able to tweak by 10% granularity -> 10Hz; 1% granularity -> 1Hz.


You're right. I was a bit confused (never used triacs before, either).

A partially informed comment. Triacs are used in my job of dimming lights in performances and do so by 'hacking' the leading or trailing edge of the sine wave. How this is done I can't remember as I wasn't paying enought attention in my electronics course in 1987 but it certainly happens.
The dimmers I have are rated to 2400 watts but 4800 watt units are readily available.
Cheers
Doug

 

[newguy]

Your mains voltage is a sine wave with one positive and one negative excursion. The period, or total time for one complete cycle is 1/50 = 20ms. Each excursion is 10ms long. A triac can be triggered to conduct sometime "in the middle" of one of these sine peaks - positive or negative. In the absence of the trigger signal, the triac will naturally extinguish at the zero crossing of the sine wave.

Triggering in the middle of the sine wave is certainly possible, but the drawback is EMI (electromagnetic interference). In essence, the sharp vertical spike in the voltage applied to the load when it is turned on in the middle of one of these sine peaks is produced by the sum of a very large number (infinite, actually) of harmonics - of very high frequency. These harmonics will happily radiate from the power cord that connects the heater to the triac. And from the upstream cords as well.

EMI isn't that big of a deal for you, but it is for your neighbours or anyone else who may experience radio or tv interference. The power companies around here frown upon it because this type of interference is absorbed almost 100% by their transformers which can cause them to overheat. I'd suspect the power companies there feel the same way.

The easiest approach is to trigger the triac for x 1/2 full cycles - in essence "letting through" only integer multiples of the sine wave peaks. When I designed my HERMS, I allowed for 64 power levels - from 0 to 63 full (one positive one negative) sine wave periods. With my 60Hz mains, this full cycle takes just over a second, which corresponds to how often I take my temperature measurements.

You can control the firing angle on each and every sine peak, but you'll have a lot of EMI unless you incorporate a lot of power line filtering. Given the very slow reaction between power application and temperature change, doing things this quickly is overkill.

 

[mesa]

I suppose as long as I don't run faster than 100, it'll work.

Correct. As long as your not faster than 100 you'll get some sort of control. How accurate that control is when your close to 100Hz but not quite 100 is another matter.

Since the Triac will latch until the next zero crossing, the on-off cycles can be modified only by multiples of 10ms.

Not quite. You appear to be saying that you want to run for a whole number of cycles turned on then a whole number turned off. That would work but its not necessary to do that. You can only turn off at the end of every 10ms cycle, but you can turn on at any point in that cycle.

If you simply use the mains voltage as a reference (i.e. use a resistor divider and compare to the voltage on a potentiometer) to decide when to turn on its very easy to get control betwen 50% to 100% duty cycle (i.e. you can turn on whenever the voltage is going more positive or more negative but not when its returning to 0). If you want to get between 0 and 50% duty cycle you need to build your own oscillator which is either much slower so that you work roughly in whole numbers of cycles as above, or run it at 25Hz and lock it in phase with the mains voltage (you would also need an edge detector so that your triac would switch on when your comparator went either on or off)

Personally I would just run the boiler at full power all the time. If I was worried about scorching, I'd run 4 elements instead of 1 (i.e. 2 in series then two series groups in parallel) that would maintain the total power but quarter the power density (I wish I'd though of this before investing in an LPG system). If I was doing a small batch on a system designed for larger batches I'd probably just unplug one of the two series groups entirely (halve the total power).

Ultimately though, returning to the question of brewing rather than electronics ;-) I don't really know what the advantage of controlling your boil rate is? If you've got a big enough kettle to avoid boil over can you boil to hard? Or is it all about not scorching the wort in an electric system?

 

[chovain]

I've actually seen references a kind of optocoupler called a "zero-crossing" coupler. These have a bit of trickery in the output stage that delays opening of the triac until the next zero crossing. Maybe I'll look at using the MOC3041: It's got a 15mA trigger (suits the 25mA IO on my PIC), and 400uA hold current. That'll eliminate most of the noise.