Converting the finished schematic into PCB artwork has been quite slow. This is mainly because of the steep learning curve using PicaxeVSM (VSM) and DipTrace (DT) together.

VSM is a great tool for creating schematics due to its ability to virtually model circuit performance. PicaxeVSM not only does SPICE modelling, it also does picaxe code. This means that a lot of circuit design and development of code can be done 'on-screen'.

The end result of using VSM is a 'virtual-proven' schematic. It would be simple to redraw this schematic in DipTrace and then make a PCB, but this means that work that has already been done is essentially wasted. Another problem with redrawing, and perhaps a more compelling reason not to take that path, is that it is open to errors. The whole point of VSM is that the circuit has already been tested as working.

VSM is designed to work seamlessly with a number of different PCB packages depending on needs and budget. DipTrace is my package of choice because it has a free version that is more than adequate to my needs. VSM and DipTrace are capable of speaking the same language via the netlist Tango export/import sequence. There are a number of reasons it gets complicated at this point though. Firstly, the package outlines listed under VSM rarely match outlines for DT. If they do, usually the pin numbering scheme will be different.

This means that new package outline names are needed for VSM, or new packages are needed under DT. I had some trouble with VSM because documentation is poor and when I created a new component, it behaved strangely. The pushbutton of choice for the control panel is both switch and independent LED. The pictures below show the promised component and then what is actually 'placed' on the schematic.

 new component as designed

actual component when placed

I really don't know why this is a problem. It may be because both parts of the component are 'animated' under VSM. In the meantime, I've decided it is much easier to create suitable packages in DT. This is still a detailed time consuming task.

Some of the process involved is outlined in this picaxeVSM thread. Myc is creating larger pads for components in his library because he is using the toner transfer method of making PCBs. I understand what he means here through experience, and so I've chosen that path as well.

The schematic I posted recently of the control panel board shows that the pushbuttons and LED indicators inside them are drawn as separate components. They are logically separate in the circuit - that is a pushbutton press does not automatically mean that button's LED will light.

part of air-wire in DT.

D4 and SW3 are a discrete LED and switch respectively. To the bottom left SW1 & D1 are overlaid to produce the compound component.

The overlay of two components on top of each other (the pushbutton part and the LED part) seemed to confuse DT. The first run through the auto-route produced a number of errors around the compound part.

These seemed to be fixable. With some node editing, the following cleaner layout seemed to suggest all was good.

On closer inspection, the LED now has two connections on the anode and the switch (the outer four pads) is only connected on one side. The fault turned out to be an errant pad number on the switch package.

With the component package fixed, the autorouter did its job again. It seemed to be less troubled by the new circuit, but the following images show it is again confused by the compound component. The blue traces from both images are actually laid over each other. The odd routing decisions show that whatever algorithm is being used cannot cope with unorthodox human 'ingenuity'.

A little bit of manual routing clears this one up without trouble. The image below shows the corrected traces, but the red circles show that the design rules check is less than happy with my compound component.

Well this time the machine won't win - I am happy with the result and it looks like the final control panel board is not far away.

I was listening to one of the old archive shows from the Brewing Network this week and it was one of the early ones with Jamil sharing his thoughts on yeast. I've heard it said before, but he made his assertion again that fermentation is 95% of the process in making good beer.

I took notice this time because Daniella tasted his 5 year old Helles and felt like she was back home in Germany. The response from all there who tasted it was quite extraordinary.

So ... I want to make the best beer possible. And I know that mostly the beer made here is pretty good and occasionally even award winning, but at times it does not quite hit the mark.

I realised that by the time a full grain session was done, the fermentation bit was given less attention than needed. Basically, by then I'm usually a bit over the lifting and cleaning. Maybe part of the issue is that I clean the house during the in-between bits of brewing, so that by the end of brew-day clean up there has been too much cleaning all round.

The other issue is that I have gotten so used to HERMAN looking after brewing, that my attention is often somewhere else. So ... 95% is in fermentation?

Anyway, I've thought about this from time to time. I have a row of fridges in the garage that seem to multiply anytime we look away. There is a fridge for fermenting lagers, another for conditioning, and a third for serving (kegerator). Added to this is the glycol chiller that is not working at the moment because it needs to be regassed. The garage is meant for two cars, but there is now barely room for one. And I'm trying to lessen my environmental footprint and use less power, less water etc.

So I was sketching an idea the other day and figured out that if I had insulated fermenters I wouldn't need to have insulated boxes for them. This takes less room and likely less energy. The only insulated box I figured necessary was one that acted as conditioning/cellar. The cooling plant for this could be the glycol chiller once that was operating again.

With glycol as the cooling liquid, simple controllers can turn pumps on or off and pump glycol through cooling loops inside the fermenters if they are too warm. The 'cellar' can be driven by a similar cooling loop but use a fan over some piping to provide evaporative cooling from the glycol. In particular, I think these might do the job.

After hatching a plan, the next step was to see if there were any cold room panels going on ebay. Before I got that far, I discovered an old freezer close by that was no longer working. $15.50 later, I was the proud owner of an insulated box.

The photo below shows that with it on its side, the top lid becomes a side door for keg access. The compressor shelf will need to be removed though. Currently it will only fit 4 kegs inside, but without that shelf it should fit 8. Behind where this shelf is I can fit the heat exchange components mentioned above.

I had a look at the glycol unit. It seems to run ok, just not cool. The controller looks good as does the compressor parts. It looks like it has some simple access points for gassing so hopefully that is all that is wrong with it and that it will hold the gas ok. I'll see if I can get it sorted next week.

Now that we are getting close to building the control circuit for HERMAN 6, it is time to make some final design decisions. I find this phase really difficult, as I want to keep all my options open, and yet the more complex something becomes, the more it slows progress.

I intended to install float switches in the tuns with electric elements to prevent heating while the elements were not covered. It should have been incorporated into the first model, but I have been reluctant to cut a hole in a perfectly good stainless steel vessel just in case ...

Anyway, it is now time to do it.

I wanted to use the float switches to not only control power switching, but also light a panel indicator to show what the float was doing. Inputs are now at a premium on my picaxe, and while it is possible to do, it is really unnecessary.

I then began to think through how the physical wiring of float switches, solid state relay (SSR) switches, and power wiring might come together. The sketch below shows a complicated way of doing things.

The reason it is complex is because all the SSRs are currently sitting in one box underneath the control panel. This seems like a good idea until the float switches are introduced.

So I began to think about mounting SSRs directly onto tuns. The drive to the SSR from the control panel would simply loop through the float without the complex wiring of the drawing above. The wiring shown below shows a much simpler configuration. The only downside I can see is that the 240V sockets to the tuns would be permanently live. Currently they go through the SSR box and are only live during the brew. I think this is something I can live with considering the machine has residual current protection built in.

I spent the morning today working on the new control panel - the panel buttons and indicators. The control panel artwork has been tweaked a little so there is an update in the HERMAN6/Design section under files.

I spent most of the time working out how the buttons would function before finalising the schematic. As an example, the timer has three buttons - one that will increment minutes, one to decrement minutes, and the other to start and stop the timer. Thinking a little more about it, a timer reset would be useful. I have a little kitchen timer that resets when you hold its two adjusting buttons down together. This won't work in my case, because all the buttons are decoded on a single picaxe ADC input. This means that the button highest on the resistive ladder will be the only one 'seen' by the picaxe.

This isn't a problem though, because it is simple to indicate a long button press (ie. the button is held down rather than pushed). So a button hold will reset the timer.

This process is needed for all the buttons, and working it out before a component is laid down will save a lot of heartache later. The heat chamber control buttons are now mash temperature control buttons, with the 'on' button activating the recirculation control loop.

I've thought about having the option of adding the heat chamber back into the system as a heating boost controller. The simplicity cycle suggests I cut the idea, so I'm not adding any extra buttons just in case. I figure that if I do things like that later, I can add the buttons then.

While all the control panel buttons have LEDs in them, not all of them need to be controlled. To simplify things, I'm only going to wire up the ones that I want to light up .... despite the undeniable urge to over-complicate things .... simplicity now!!!

LED indicators on control panel

So the control panel schematic comes in two sheets - one for the buttons, and one for the LED indicators. The indicator sheet shows 16 LEDs which will ultimately be driven by an output extender board on the extension bus. I'll finalise that circuit some other time, but I have done testing with code and a VSM schematic, so I'm confident it will work ok.

The two schematic sheets are posted as bitmaps under the files section of the blog site. If anyone is interested in the actual VSM files, just let me know.

So next step is working on the netlist export on VSM so that I can use DipTrace to build a PCB.

We never did get around to the last test before brewing - but that is something we can do this weekend.

But a HERMS system WILL NOT WORK if there are flow issues!

Ok, so we brewed a Helles last Monday. I've been wondering about the grain bill and getting too adventurous. 10.5 kg of grain should be ok in a 38 litre igloo cooler ...

At this point I'm not sure if there were problems of trapped air on the pump inlet, or if the grain bed was set too tightly. If only I'd taken one or two educated measurements, I would be enlightened at this point.

The liquor did flow, but only very slowly in the recirculation loop. I know from experience that it is simply not worth the heartache to try and step from a saccharification rest to mash out. The sparge water pretty much did this anyway, albeit taking the entire kettle fill time to do it.

What I should have done was let gravity do its work, draining a sample of mash liquor and working out what this rate was compared to through the pump working against gravity. That would have given me the info I needed. Same rate by gravity as by pump would show a compacted grain bed. A greater rate draining by gravity would suggest a pumping issue, and in my case almost certainly trapped air.

With more than 10kg of grain in the tun, it means there is not much room for rice hulls. I put some in, but would have liked to add more. At least while this continues to plague me, I must remember not to overload the mash tun.

I guess the main reason I did not collect the data was I was distracted cleaning out a cupboard while I was brewing. It was satisfying to get that sorted, but the brewing mayhem continues. Must remember to focus on brewing while brewing ...

A pleasing thing about the brew day was doing the pre-warm of mash tun like I did last time. I hit the target of 65C precisely (65.1 seems close enough to call precise ). So I will continue this method.

The change to the cleaning routine has meant that any flaky matter from the heat exchange coil no longer clogs the plate chiller, so that is a step forward. The Helles is fermenting away strongly, and it promises to turn out well.

All things going well, tomorrow I will get back to the HERMS pre-heat testing that I wrote about last time. But I'm also getting the urge to construct the new HERMAN control panel. And there are a few leaks to repair on HERMAN.

So many things to do, and so little time.

I ran the test outlined in the last blog:

• stablise mash at 62C
• preheat HLT to 69 + 2*7 + 5 = 88C
• set mash target to 69C
• set HLT target to 69C + 5 = 74C
• log the results with particular interest on final HLT temperature and time taken for mash step.
• work out what to do next.

OK, some interesting observations ...

First, with a target of 62C and the HLT at around 67C, the mash liquor settled nicely at 62C with pretty much a flat line - nice.

The blue line is the HLT temperature, and the ripple shows that there is no stirrer or pump in it to mix the liquor around. I have a mixer that came with my glycol chiller that I'm currently not using, so it might be good to add this to the HLT. Incidentally, the time scale on the graph says hours, but the markers are actually the minute values of the second hour. The graph shows 8 minutes of stable mash liquor temperature.

From this point, I set the HLT to 88C to perform a pre-heat, with the intention of doing as rapid as possible a step up to 69C. It took 22 minutes for the HLT to step up 20 degrees. During this time it was interesting to observe that the mash was not as stable as it had been.

The graph shows that the mash temperature began to oscillate, just dipping below target and then peaking around 1 degree higher. This makes sense, because the temperature probe in the mash liquor is about half-way down the tun. By the time the heat has found its way to the probe, too much hot liquor has already been dumped into the tun so the temperature continues to rise around the probe as this hot liquor slowly finds its way down.

If the pre-heat is short, this may not be of any real concern, but I will think a bit more about this. It might be fixed by pumping for a short time, say 30 seconds, waiting for same, and then pumping again if needed.

The next graph shows a result that is very close to what I'd expected - that the extra heat in the HLT can speed up a step, and that the amount of extra heat needed is quite predictable, meaning it is not too hard to do a quick step and rapidly return to a stable mash temperature.

The HLT is shown here rapidly losing heat as the mash liquor rises very quickly initially. In about 4 minutes, the mash temperature has jumped from 62C to 67C, an impressive figure for this setup. Although not shown on the graph above, the recirculating liquor temperature did not rise above 75C and settled quite quickly to 70C. This is good, because it means that enzyme activity will not be radically affected by this process.

After the quick rise, things tail off quite quickly, as the difference between HLT temperature and mash liquor ceases to be high. It is interesting to note that the mash liquor does not ever reach 69C, but rather settles at an even 68.

It seems like the system heat losses rise as the target temperatures rise, which is understandable, although I'd hoped it would not have been that great.

The graph above shows that during minutes 40 to 55, the HLT was set to 74C. Between 55 mins and hour 4, the HLT was raised to 75C. During the next 15 minutes, the mash liquor temperature barely rose, settling in the low 68s. The HLT was set to 76C at about minute 15, and the mash liquor slowly made its way to the 69C target, albeit still a little sluggishly.

It is obvious that the HLT did not have sufficient heat mass to perform the required step, although it was close. It is worth tweaking the algorithm, so maybe something like 2.5 times the step difference and analysing the result. It also seems that the system heat loss can vary significantly between cooler and higher temperatures. It would be worth testing the system with a generous heat loss figure (say 8 degrees) and testing stability at both 62C and 69C.

A further test would probably reveal if the algorithm needs a changing system heat loss, or if a single figure can cope with the entire range of 40C to 76C for mashing. So tomorrow some more testing, and then on Monday we will brew a Helles.

I ran some preliminary tests with the new coding tonight to get a feel for how HERMAN is functioning in this latest configuration. A thread on the Aussie homebrewers forum I read today got me thinking about how many different combinations of machine I've had over the last 7 years ... Talk about a 7 year itch!!! I think I have tried just about every configuration of HERMS and RIMS in that time.

The first iteration was a standard HERMS with a heat exchange coil in the hot liquor tun. The HLT was 25 litres and heater 2400W. This seemed too slow, so when the rig was upgraded to a 40 litre HLT, I converted to a separate heat exchanger with a volume of 15 litres and a 3600W element. But it seems I'm never satisfied ...

The next configuration was RIMS with a heat chamber fitted with a 3600W element that was almost impossible to control. The number of mishaps rose in proportion to the grunt available .

And so back, full circle. Now a 40 litre HLT with a 3600W element and some trickery to pre-heat prior to a step change in the mash.

I've tested tonight with just water. When grains are added to the mix they have a greater thermal lag and capacity - which means everything happens slower. It takes longer to heat a grain bed, and it takes longer to cool one. The time to heat is not so much my concern at this stage, rather the possibility of overshoot.

With the water run, I assumed a generous system heat loss of 5 degrees C. This means the machine should be able to reach the target mash temperature with comfort, rather than take forever inching its way to target, and never quite making it. I suspect this is a good way to run the machine, with a margin of error.

I stablised the rig with mash temperature at 62C. With a step to 69C in mind, I set the HLT at a generous target of 83C. I had figured this number out in my head, and it made sense at the time, but I can't work it out now . The HLT was allowed to heat to this temperature prior to changing the mash target to 69C.

It took 12 minutes for the machine to step up the 7 degrees in the mash. During a real mash, this will take longer due to the thermal mass of the grains. During this time, the HLT only dropped down to 81C, so the heating element is nearly capable of matching the heat required for the step.

My initial impression is that a varying HLT target might have some value - such as if the mash is 5 degrees lower than target, the HLT might be targeted at 10 degrees higher (taking into account system losses - ie. 10 + 5 degrees higher).

Before committing to this, I intend to run the following test:

• stablise mash at 62C
• preheat HLT to 69 + 2*7 + 5 = 88C
• set mash target to 69C
• set HLT target to 69C + 5 = 74C
• log the results with particular interest on final HLT temperature and time taken for mash step.
• work out what to do next.

The HERMAN project has been going on for a lot longer than the blog site here. This means that there is a lot of information missing from these pages. Garret Sever in a recent blog mentioned a power supply module that he bought for his picaxe based brewing sculpture. It reminded me that our own power supply has not yet found its way into a blog entry.

I can't claim credit for the circuit design - I think it came from a poster on the picaxe forum. We did design and build the circuit that is below and attached it onto a PC power supply. PC supplies are great because they are cheap and plentiful and can supply both 5V and 12V at many amps. If needed, there is also a -12V rail and 3.3V rail for added versatility.

With our supply we decided that the 12V rail would be used to supply anything that was potentially noisy or demanded a bit of current flow. This includes things like relays, solenoids and motors. If these components needed a different voltage, say 5V, we would still use the 12V line and use a regulator to drop it. This design philosophy means that the 5V line can be used solely for logic (picaxe and any other logic gates needed) and can be suitably filtered to provide a clean rail that the picaxe demands.

We decided that a PC supply on its own was not as clean as we wanted, so the circuit below was added.

Click on the circuit for a full-sized version. The original ExpressPCB schematic file is available under files/HERMAN6/Design.

The circuit board was made using ExpressPCB software, which was the best I had available to me at the time. I'm happy to have pensioned it off though. Below is the mechanical drawing, but if you want to make a board you can find the *.pcb alongside the schematic.

The completed PC supply with extra filtering is shown below. The black wire link at the top rear right connected to the screw terminal block is the control to switch on the supply. The link here ensures it is on as long as mains power is supplied, but we intend to extend this switch to our control panel.

The image below shows wiring of PC supply components. It is the green wire on pin 14 of the left-most connector that is used to power the supply on and off. You can click on the image to see it full size.

Overall, we think the PC supply makes an ideal power unit for a picaxe based brewing sculpture.

With the mod from a RIMS to HERMS, the brewing machine needs some fine tuning of its control system.

RIMS controls are much more critical than HERMS. PID is pretty much essential for RIMS but not for HERMS. So I've decided to keep it simple and drop the PID coding, and replace it with a couple of IF-THEN statements.

These statements are to apply only if a target temperature has been set on the mash tun. This means that the system will be recirculating mash liquor in order to regulate mash temperatures.

So, using pseudo code:

'Regulate mash temperature by cycling pump on/off

IF MASH_TEMPERATURE >= MASH_TARGET THEN
     PUMP=OFF
ELSE
     PUMP=ON
END

'Ensure HLT can supply sufficient heating for mash

IF HLT_TARGET < MASH_TARGET + SYSTEM_LOSS THEN
     HLT_TARGET = MASH_TARGET + SYSTEM_LOSS
END

The main mechanism for regulating mash temperatures is turning the pump on or off. Obviously, when the pump is not recirculating liquor, no extra heat is added to the mash. When the pump is on, the liquor passes through the heating coil in the HLT and adds extra heat to the mash liquor.

I must admit I am not sure why many recirculating sculptures have more complex heating bypass systems in them. It seems way to complex, even for me, to have an extra solenoid or two to switch between heating and bypass path when just cycling a pump will do the same job. I've also seen systems where an attempt is made to control the speed of the pump to control the speed of liquor flow. Again, what could be more simple than turning a pump off when the mash is at temperature, and on again if it drops below?

The nice thing about a HERMS system, is that once you figure out the system loss you can pretty much set the HLT temperature and let the machine to the rest. This machine will do that, but by using the pump on/off cycling system above, it gives the option to shorten the time between temperature steps in the mash. This is explained in the example after the schematic.

The secondary mechanism for regulating mash temperatures is through setting a target on the hot liquor tun. The system loss component is the difference between the HLT temperature and the liquor flowing into the mash tun through the heat exchange coil. In my system this is around 3 degrees C. The coding of the second IF-THEN statement ensures that there will be enough heat supplied by the HLT whenever a mash target has been set. This can be manually adjusted up by the user but not down. (In actual practice, this just affects the target, the user can still deactivate the HLT if needed.)

As an example, suppose the mash is sitting at 67 C for a saccharification rest and we want to step up to 75C to perform a mash out. If the HLT was the primary means of regulating mash temperatures, we would need to wait until the end of the 67C step before setting a target on the HLT of 78C. Doing this is ok except that the thermal lag in the system means it will take a long time for the mash to reach its target.

Suppose now that 15 minutes before the end of the 67C step the HLT target is adjusted to 86C. As the HLT rises in temperature, the mash is prevented from over-heating by the pump turning off. Suppose that by the end of the 67C step the HLT has reached its target of 86C. At this point the mash target changes to 75C and the pump turns on because the mash temperature is now less than its target.

As the pump continues to recirculate liquor, a significant amount of heat is drawn out of the HLT and its temperature drops rapidly. As this happens, the mash liquor temperature is increasing more quickly than if the HLT was slowly heating up to 78C. If the system is balanced, as the mash approaches its target of 75C, the HLT will be close to its target of 78C. Should this happen, the pump will constantly recirculate liquor in the system without the need to cycle off.

That's enough for theory. We intend to brew on the weekend so will test it out in practice.

After about three weeks of preparing for an overseas holiday and then enjoying Malaysia and Singapore, it was nice to get back to some HERMAN work. Last brew day I encountered a disturbing problem. Despite best efforts to clean the inside of the heat exchanger coil, flaky dried wort found its way into the fermenter and clogged up the plate chiller.

The good news is that the Belgian Wit is fine despite the unwanted flavour addition. It also seems that the oxidising cleaner soak I gave the plate chiller over the last two weeks has eaten away any remaining flakes.

This morning I began to think about altering the plumbing to improve the flushing path through the chiller. This meant moving the 'hot liquor in' line close to the chiller, ensuring the high pressure hot water did not go via the heat exchange coil, bringing flaky debris with it.

I posted a revised layout in a recent blog but realised a problem with the layout. If a connection was made at the plate chiller, there would be no way of stopping flow into the kettle if the hot liquor solenoid was on. The schematic below fixes this issue. It shows the hot liquor line connecting on the pump side of the backflush valve. Each vessel can now be individually isolated via valves.

The schematic has been refined a little to make the plumbing layout clearer. The full picture is available as a downloadable jpg file, and the original corel draw file can be downloaded as well.

Next steps include building some shallow walls on the bottom shelf of the machine to hold stray water (as they say 'leak happens') and stop it running directly onto the laundry floor. I'm also intending to do some picaxe code tweaking to account for the change from RIMS to HERMS configuration. Beyond that a new switch panel for the control system and then final testing and building a picaxe 28x1 based control system. That will more than see my final week of leave out.

Things have been quiet on the HERMAN front for a few weeks as Ani and I have been visiting family and holidaying in Malaysia and Singapore. With Melbourne getting cold, it was always time for a beer wherever we were in the tropics .

Tiger beer is popular in this part of the world, and although it is meant as an easy drinker, in my opinion it is much nicer than most megalagers in Australia. I would drink it any day over the locally made Carlsberg as well. One of the quirky things is that you have to specifically ask not to have ice in your beer in these places. It makes sense because it warms up so quickly that ice is standard serving practice.

A can of Tiger costs around 60 cents Australian locally. It was a bit of a shock to see a slab of 24 cans in my local liquor shop back in Melbourne for $45.

Night view of Singapore

Anyway, for a city, island and country that is very fussy about being neat and proper, where chewing gum is illegal, beer and other alcohol runs a plenty. Once the city began to wake up (at around 8pm at night), the mall closest to where we were staying was having a vodka party. The cocktail waiters were dancing and spinning their mixers with great fanfare. We decided that vodka shots was not our style though, and headed for Brewerkz on the river.

Enjoying an award winning IPA at Brewerkz.

The beer at Brewerkz was excellent, with about half of them collecting awards this year at the Australian International Beer Awards. The double IPA goes down too easily in this climate! They even had a hand-pumped English ale on tap. The waitress knew enough to warn me it would be flat.

While the beer was great and the atmosphere quite nice, they do not run tours which was disappointing.

We only had about 24 hours in Singapore, and nothing was open the next day until after noon. We couldn't even find a place to eat breakfast except for our hotel. By noon we were thirsty again, so found our way to the Pump Room brew pub. We didn't stay there long, but the bohemian pilsner was excellent and preferred over their own pump room lager.

The pump room at Clarke Quay.

Our next stop was the Paulaner Brauhaus. There was not much happening here so no tours but we were allowed to take lots of photos.

The place was more impressive than their beer which was a touch disappointing after our previous stops. I'm sure that the quality is much better in Munich as well.

Lots of shiny equipment to salivate over behind the bar.

The place we were most interested in seeing was our final stop before flying out. Raffles hotel is an icon of the British empire. One of the 'must do' items listed in the lonely planet is to visit Raffles, order a Singapore Sling, and throw peanut shells on the floor. Of course we did the tourist thing, and enjoyed the ambience of the place.

Sipping a Singapore sling at Raffles.

After two weeks of travelling, two weeks and two currencies, it was time to come back home. Now it is time to add a few refinements to HERMAN and brew again this weekend.