Am I over-complicating things... Data Logger and Air Conditioner Control

[fritzzz]

Data Logger and Air Conditioner Control

Hi,

I've just built a wine cellar room and would like to fit it out with something to monitor the temperature and humidity in there plus control the split system air conditioner that cools the room. I was looking at using a Picaxe and associated components and I wanted to know if I could do the following with it or if I am over-complicating things:-

• Four temperature probes
(1) & (2) Two located inside wine bottles filled with water to give the closest possible reading to the temperature of the wine – in two different parts of the cellar, logged over time
(3) One located inside the cellar measuring the air temperature – to control the split system air conditioner which provides the cooling. This one is required as the split system air conditioner will only cool down to 18 degrees C out of the factory – would like to disconnect the thermostat on the unit and connect it up to the cellar one – perhaps using an offset to trick it to run cooler
(4) One located outside the cellar measuring the air temperature

• Two humidity probes (not essential)
(1) One located inside the cellar to measure the humidity
(2) One located outside the cellar to measure the humidity

• LCD display would be mounted on the outside of the room so I can see the current temperature in there when walking past

• All of the measurements logged and then somehow periodically upload the data from the data logger to a PC
- Either have the PC on all the time and do it at regular intervals – advantage of this is that I could log in remotely and see what is happening but this is not critical
- Ideal would be for the data logger to transmit the data to the PC whenever it happens to be turned on – PC is in our study and it is usually turned on every couple of days

I think the options I have are:-

• Measurement, data logging and air conditioner control all done by Picaxe
• Stand-alone data logger feeding data to Picaxe which then controls A/C
• Stand-alone data logger feeding data to a PC running some sort of application which then controls the A/C

Work I am trying to work out is if this is over-complicating things by trying to do it all in a Picaxe, especially as I am no electronics whiz….

I would appreciate any suggestions as to what people think is the most logical, simple and reliable approach at a reasonable cost.

Many thanks

Chris

 

[Dippy]

Hello Chris,

All that can be done with PICAXE (or PICAXEs) and a bundle of other components.

Sadly, I haven't got the time to list out what you will need.

But step number 1 is to convert your textual requirements into a big schematic then break down each sensor section into a circuit design and parts list.

Quite a task and very interesting - this is going to be a long thread.
But keep at it.
If you can break it into modules then people can help.
As one long project you might get in a muddle.
Then the bits can be put together into a single system.

Questions that might help:
1. Your budget.
2. Your experience in electronics and programming.
If the answers to all of the above is "nearly zero" then we have a job on our hands

 

[Jeremy Leach]

Hi, interesting project ... a few initial questions ...

-What level of accuracy do you think you might need for temperature and humidity?

-How often would you want to take a sample and how many samples would you need to 'buffer' between uploads to your PC?

-What if you went on holiday and the buffer overflowed - would losing some data be a disaster?

-What control inputs does your Air con have and at what voltage level ?

?

 

[boriz]

I’d say yes. Overcomplicating it.

Why do you need 4 temperature sensors? The outside one is irrelevant and the three inside ones will all disagree. So which one does your program trust? What do you need humidity readings for? That won’t affect the wine will it?

On the face of it, the sensor-in-a-bottle idea looks good. But I think you’ll find that all you’re doing is slowing down the response of the sensor. EG: By the time the too-high-temperature has soaked through the glass and liquid and the sensor detects it, ALL the wine is too hot. Then after the cooler kicks in, you have the same problem again, all the wine will be too cool before the sensor catches up. So all the wine will be at the wrong temperature most of the time.

Better to use only one sensor, air coupled, and select its location carefully. And make sure the air temperature is uniform by moving it around the room with a fan. Good room insulation will probably help a lot.

If I were you, I’d start by getting a Picaxe 14M with one temperature sensor to turn an LED on and off at appropriate temperatures. That in itself should prove to be challenging enough for a newbie. I suggest a 14M because the next step, driving an LCD, can be done easily with Hippys code published someplace else on the forum.

 

[BeanieBots]

I agree largely with what Boriz says.
In particular, the bit about sensors. You only want ONE sensor for your control system.
There may be an advantage to having a second sensor in a "dummy" bottle, but only used to indicate what actually (may) have happened if your control system failed for a period of time. Do NOT use the "dummy" sensor for control for the reasons given by Boriz.

 

[kevrus]

I would recommend that you ensure the thermostat is just a simple thermostat as some 'stats' for AC units also have time delays built in so as to stop 'short cycling' of the compressor which would lead to damage...3 to 5 mins is a common delay period that I have come across (i'm not an AC engineer so I stand to be corrected)

 

[fernando_g]

Congratulations on your idea, it is a very worthwhile (and PICAXE-able) project. I also enjoy wine with my meals, but I'm not a connoseur by any stretch of the imagination....I can't afford the expensive wines, let alone a full fledged wine cellar.

Since by your own account: "I am no electronics whiz" perhaps the shortest way to go is to purchase the AXE110 dataloger. This will provide you with a test bed, has exactly the functions your are looking for, and can be easily expanded, including the LCD-display capability.

I cannot overemphasize the fact that a fully functional and debugged hardware platform removes many headaches when developing a project like the one you are planning to tackle. It will allow you to concentrate on debugging and optimizing the software.

I would also suggest that you get the real time clock option, since that would allow you to log additional information; I.E. how long your air conditioner operated, to estimate energy usage costs.

I was puzzled by your statement that the air cooler will only go to 18_C, what is the optimal temperature to store a wine?

 

[fritzzz]

Hello Chris,

Questions that might help:
1. Your budget.
2. Your experience in electronics and programming.
If the answers to all of the above is "nearly zero" then we have a job on our hands

Thanks for the response - answers to your questions!
1. Around Aus$750
2. Virtually nill in both although I have built kits before and I can edit other people's code

Hi, interesting project ... a few initial questions ...
-What level of accuracy do you think you might need for temperature and humidity?
-How often would you want to take a sample and how many samples would you need to 'buffer' between uploads to your PC?
-What if you went on holiday and the buffer overflowed - would losing some data be a disaster?
-What control inputs does your Air con have and at what voltage level ?

- temperature accuracy around ± 0.2 C
- humidity accuracy around ± 3 to 5% RH
- sampling perhaps once every 5 minutes
- buffer in the order of a couple of weeks - then I could do the upload manually before the buffer is full
- no real drama if some data was lost
- not sure - that is tonight's job to pull some covers off and have a look

Why do you need 4 temperature sensors? The outside one is irrelevant and the three inside ones will all disagree. So which one does your program trust? What do you need humidity readings for? That won’t affect the wine will it?

On the face of it, the sensor-in-a-bottle idea looks good. But I think you’ll find that all you’re doing is slowing down the response of the sensor.

Better to use only one sensor, air coupled, and select its location carefully. And make sure the air temperature is uniform by moving it around the room with a fan. Good room insulation will probably help a lot.

If I were you, I’d start by getting a Picaxe 14M with one temperature sensor to turn an LED on and off at appropriate temperatures. That in itself should prove to be challenging enough for a newbie. I suggest a 14M because the next step, driving an LCD, can be done easily with Hippys code published someplace else on the forum.

Only two of the four are essential:-
- the one measuring air temp which controls the A/C - this is the critical one
- the one in the bottle which shows the temp of the wines and this one would be used to refine the control
- the other two are nice to have - outside air shows how well the cellar is insulated from day-to-day variations, having another one in a bottle gives me an understanding of the gradient from top to bottom in the cellar, the A/C unit has a sweep function for stirring the air but I don't know how well it works

Humidity is a nice-to-have - not so critical with most wines being screw tops but about 30% of mine have corks and they like things around 75% RH

Even as a newbie I'd prefer not to buy one kit and then have to buy another if possible. I would just rather start with the "right" one and work on one sensor input at a time

I would recommend that you ensure the thermostat is just a simple thermostat as some 'stats' for AC units also have time delays built in so as to stop 'short cycling' of the compressor which would lead to damage...3 to 5 mins is a common delay period that I have come across

You are right - running the unit to a lower temp may require some control for switching it on and off to both stop it icing up and to stop it being cycled too frequently

Since by your own account: "I am no electronics whiz" perhaps the shortest way to go is to purchase the AXE110 dataloger. This will provide you with a test bed, has exactly the functions your are looking for, and can be easily expanded, including the LCD-display capability.

I cannot overemphasize the fact that a fully functional and debugged hardware platform removes many headaches when developing a project like the one you are planning to tackle. It will allow you to concentrate on debugging and optimizing the software.

I would also suggest that you get the real time clock option, since that would allow you to log additional information; I.E. how long your air conditioner operated, to estimate energy usage costs.

I was puzzled by your statement that the air cooler will only go to 18_C, what is the optimal temperature to store a wine?

I thought the AXE110 with buffer, real time clock, LCD display would be a good start as it gives me four inputs.

How would I do the A/C control?

With storing wine it is more about minimising short term fluctuations, so at the moment my cellar keeps things very stable around 18 degrees C, this is better than keeping it at 16 but having it go down to 12 and up to 20 each day. People's opinions as to the right temp vary but 16 seems to be a good basis to start with.

 

[lbenson]

Temperature accuracy of .2 decrees C is likely to be difficult with the sensors typically used in picaxe circuits. The DS18B20 will give measurements to .0625 degrees with readtemp10, which is fine resolution, but how close to a calibrated measurement? Do you have something to check with which gives that degree of accuracy, and is it calibrated? Is there a practical need to have accuracy to more than a degree or two C? That should be achieveable without too much difficulty.

The DS18B20 data sheet is reported to specify an accuracy of +/- 0.5°C (I confess to not having read it, not needing that degree of accuracy).

 

[BCJKiwi]

In what is (presumably) a virtually closed environment and hopefully not damp, there should not really be any icing issues as condensate should be delivered outside and the space will become quite dry over time assuming the aircon does not have any re-humidification capability.

 

[fritzzz]

In what is (presumably) a virtually closed environment and hopefully not damp, there should not really be any icing issues as condensate should be delivered outside and the space will become quite dry over time assuming the aircon does not have any re-humidification capability.

You make a very good point which I hadn't thought of so that is good news - potentially one less thing to worry about unless it gets too dry which isn't likley.

 

[fritzzz]

Temperature accuracy of .2 decrees C is likely to be difficult with the sensors typically used in picaxe circuits. The DS18B20 will give measurements to .0625 degrees with readtemp10, which is fine resolution, but how close to a calibrated measurement? Do you have something to check with which gives that degree of accuracy, and is it calibrated? Is there a practical need to have accuracy to more than a degree or two C? That should be achieveable without too much difficulty.

The DS18B20 data sheet is reported to specify an accuracy of +/- 0.5°C (I confess to not having read it, not needing that degree of accuracy).

I'll take a look at the datasheets to see what they say. The sensor in the liquid would ideally be more accurate than the one in the air. The one in the air could be +/- 0.5°C and that would be fine.

Any less accurate than that wouldn't be much good as I am trying to avoid lots of short term fluctuations which are the enemy of storing wine, e.g. 18 C +/- 0.1C per day would be better than 16C +/- 2C per day.

 

[MPep]

Yeah but the temperature in the bottle would respond very slowly to temperature changes.
Although it would show the typical temperature of all the wine bottles stored (averaged), any short-term variation that occurs would not reach this sensor. The thermal lag would be too great to have much effect.

I suspect you need some form of PID controller. Alas, I am not the person to ask how they work.

 

[fernando_g]

"How would I do the A/C control?"

Since you're performing all the monitoring and control functions with the PICAXE, perhaps the best approach is to have a qualified service shop bypass the unit's thermostat completely. He could also install a power relay (if not already equipped with one) which usually have a 24 VAC coil. You can easily mange this coil with a TRIAC optocoupler or another smaller relay.

The PICAXE can then drive this small relay, to control the temperature with a far more sophisticated temp-control scheme, and it could additionally provide the 3~4 minute delay to prevent frequent compressor cycling, and even frost protection.

Just an idea.

The important thing is that once you have PICAXE'd your project, you can start with a basic control, and later upgrade and make refinements easily. For instance, you could add a LDR photocell, which would tell you how many times the cellar has been visited. Thinking about that, it will tell you if someone has been drinking from your wine!

 

[boriz]

"18 C +/- 0.1C per day"

Day and night...summer and winter...

WOW. You don't want much do you

A hermetically sealed NASA space lab would be proud to achieve that!

 

[Jeremy Leach]

I'm beginning to think that the temperature stability will be limited not so much by your sensor accuracy but by the response of the air-con unit. The air con thermostat will have some in-built hysterisis that is bound to be >>0.1 degrees. Even if you eliminated the inbuilt thermostat and controlled the air-con directly from the picaxe system there will lags in response in the control system as a whole. A difficult problem.

 

[boriz]

You’ll need to seal the room, modulate the coolers/heaters precisely, wear a space suit, use an airlock...

 

[slimplynth]

Conventional air furnaces/ drying ovens use PID control to maintain a temperature as close to setpoint as possible by monitoring a single fixed position thermocouple.

This works well but with some vacuum furnaces, the control is often done by monitoring the temperature using job thermocouples.

Typically this means monitoring:

* A sensor in a heat sink representative of the smallest section of the material being heat treated - to prevent overshoot.

* A second sensor representing the largest section, to ensure complete treatment throughout.

* A third sensor placed in close proximity to the heating elements.

For some vac furnaces where thermal lag of the job is an issue... something more than PID control is required - which is where cascade temperature control is employed.

Attached are the PDF's from the Eurotherm website, maybe they'll help you figure out how (tricky) to use a Picaxe to achieve this.

edit: DS18B20's have a fair bit of lag, i'd use thermocouples but sometimes thermal lag is a good thing. I spent a few years surveying furnaces.. upto 20 thermocouples distributed through the working volume, some high temp furnaces benefited from having the control thermocouple in a ceramic sleeve (mainly to prevent oxidation/contamination of the sensor). Lower temp curing ovens having bare wire control thermocouples surveyed better, as they matched the sensors surveying them - overshoot of the surveying sensors was less likely.

 

[eclectic]

One of the things that I enjoy
about this site,

is the level of erudition shown by many of the participants.

Even if I don't need the knowledge,
or even, indeed, if I don't understand the answer,

it's still good to know that the expertise is there.

e

 

[slimplynth]

On reflection, get as many sensors in there and survey it to see what the current situation is, make some nice graphs over a period of days/weeks (get to know the beast). Might also want to consider doing a good job of insulating the room too.

 

[BeanieBots]

Good advice slimplynth.
Characterise the PROBLEM not the solution.
Controlling to the levels described will be quite impossible as Boriz so nicely points out.
The reason wine is stored in a cellar is because the environment is inherrently stable down there. However, there will be significant stratification. Shoving in an air circulating air-con unit could easily make things WORSE!
You might need to consider something along the lines of radiators with cooled water. This would keep air flow low yet still allow a constant temperature to be maintained without having negative effects on humidity.

 

[slimplynth]

I'm currently storing red wine in my stomache picaxe and wine, something i now avoid. I found the link attached a nice read...

 

[inglewoodpete]

Just some thoughts on using a sensor "in a bottle of water in the wine rack".

For the air temperature to have much affect on the wine in the bottle, a significant amount of time would need to pass. I imagine that 15 to 30 minutes would typically be required to get a cellar temperature to change much outside the bottle, let alone inside.

Also, liquids being liquids: the sensor inside the bottle would need to be at the highest point of the liquid to best detect changes. At least, any temparture change within the bottle would find the sensor fairly quickly, through convection!

Finally, I think I'd need a glass or two of red with a few PICAXE-savvy friends to contemplate the problem and come up with the best solution. And appreciate the wine, of course.

 

[Jeremy Leach]

Perhaps put the picaxe design effort into a robotic wine bottle selector/transporter that can deliver a bottle through a tiny door - this way you won't get a huge temp fluctuation when you open the cellar door .... Or just have a long straw ?

 

[demonicpicaxeguy]

i think prior to any temprature control project it would be a wise idea to log say 1 weeks worth of bottle and and air tempreature inside this room, to see how much cooling or heating it may need

what kind of wine is it?
where on this planet are you located?
how is the wine corked?
what have you done to limit the amount of natural light entering the room or is it an underground and windowless room
have you even stored and aged wine before?

 

[fritzzz]

I'm not sure what a lot of the comment have to do with solving the problem but here are some answers to the various questions and less than helpful comments....

The cellar is already built and is well insulated with polystyrene walls etc. It is located internally in our house and it receives no heatload from the walls, floor or ceiling space. There is no natural light getting into it.

The air conditioning unit is in there already and is doing a great job of holding the temperature stable around 18 degrees C having recorded it for the past twelve months with a less than desirable unit. I don't need to calculate the heat load, I have done that when I sized the unit.

I want to cool it to 16 degrees C and as such I need to override the controls on the A/C unit which cool it to a minimum of 18 degrees C. If I could work out how to send a 2 degrees C offset to the unit I would just do and I wouldn't need all of the other stuff apart from a data logger but I can't.

The cellar contains a mixture of red white, white wine, ports, muscats and other nice things. I am in Melbourne, Australia. The wine is a mixture of corks and stelvin seals (screw tops)

I'm not sure what the question "have you even stored and aged wine before?" has anything to do with answering the question.

My conclusion is that it is doable but I'm going to have to work it out myself.

 

[hippy]

The air conditioning unit is in there already and is doing a great job of holding the temperature stable around 18 degrees C ... I want to cool it to 16 degrees C and as such I need to override the controls on the A/C unit which cool it to a minimum of 18 degrees C. If I could work out how to send a 2 degrees C offset to the unit I would just do and I wouldn't need all of the other stuff apart from a data logger but I can't.

It should be possible to get the cooler to cool to a lower temperature by faking the temperature it perceives to be 2'C higher than it is. It would be worth contacting the manufacturer to see if there is a simple way to make it cool to 16'C, failing that a circuit diagram or reverse engineering the unit could reveal what needs to be changed. If it uses an analogue sensor it may simply be a case of increasing or lowering resistance for the sensor.

 

[BeanieBots]

Many units are a simple bi-metallic contact. No electronics (except perhaps a relay) is involved.
The bi-metallic trip point is calibrated by use of a set-screw.
A few turns of the set-screw should be enough to offset the calibration by a few degrees.

OR, as Hippy suggests, fool it.
That could be done with a small local heater (1/5W resistor) close to the sensor. PWM control of the resistor would give proportional control over temperature.

If you can't find an obvious bi-metallic contact, look for a copper coil about 3/4" in diameter and maybe 1" long.

 

[demonicpicaxeguy]

I'm not sure what a lot of the comment have to do with solving the problem but here are some answers to the various questions and less than helpful comments....

The cellar is already built and is well insulated with polystyrene walls etc. It is located internally in our house and it receives no heatload from the walls, floor or ceiling space. There is no natural light getting into it.

The air conditioning unit is in there already and is doing a great job of holding the temperature stable around 18 degrees C having recorded it for the past twelve months with a less than desirable unit. I don't need to calculate the heat load, I have done that when I sized the unit.

I want to cool it to 16 degrees C and as such I need to override the controls on the A/C unit which cool it to a minimum of 18 degrees C. If I could work out how to send a 2 degrees C offset to the unit I would just do and I wouldn't need all of the other stuff apart from a data logger but I can't.

The cellar contains a mixture of red white, white wine, ports, muscats and other nice things. I am in Melbourne, Australia. The wine is a mixture of corks and stelvin seals (screw tops)

I'm not sure what the question "have you even stored and aged wine before?" has anything to do with answering the question.

My conclusion is that it is doable but I'm going to have to work it out myself.

i'm sorry if my questions came across as patronising/offensive, but there is some reason to the madness

in most wine cellars i've been into and had anything to do with, the temperature has been anywhere between 10 to 14 degrees, depending on how long the wine is to be stored,

you'll find it almost impossible to maintain a wine cellars air temperature at a perfect 16 degrees, i'll be suprised if even the currently setup doesn't fluctuate by 1 or 2 degrees, every time the circonditioning turns on and off, ideally you want to be aiming closer to the 10 to 13 degree mark that way any fluctuations in temperature caused by the airconditioner and or opening doors or ventilation, are still within a comfortable range

the other concern is that even if you find a simple way of giving the airconditioner a offset temp reading, this will put an extra load on the air conditioner, your compressor will have to run longer, certain parts will get hotter and certain parts will get colder and there could be other problems that could come up as a result, eg worst case scenario a refridgerant leak (i think that stuff can leave you impotent)

i'd maybe get the advice of a professional airconditioning guy who knows these units back to front and know the limits or performance

at the end of the day modifying an airconditioning is akin to modifying cars and it generally pays to be carefull and do it properly

 

[papaof2]

Couple of things that may be of interest.

Most A/C units deliver air from the evaporator somewhere around 12-14C. When enough cold air has mixed with the room air, the thermostat is happy and turns the unit off. The assumption is that the unit is sized to provide enough cooling for "people space" and the thermostat works for people space. Was your unit sized to cool to wine temperature or people temperature?

Getting truly even air distribution in any space is not easy; doing so in a space with air blockers (the wine racks) may be more difficult. One or more small fans that run continously at a low speed may be required to keep the temperature even (top to bottom, side to side) as in a convection oven. The best way to determine this would be to log the temperature at several locations in the room: every few feet along the wall about one foot from floor and ceiling and halfway up the wall, 1/3 of the way across the room (grid pattern) at the same levels. Or just install a small ceiling fan with a speed control and run it a slowly as possible ;-)

Ever see the telephone/cable/etc guys set up the enter a manhole? They follow a very specific procedure to ventilate the space (to clear any possible flammable/toxic fumes) before entering. The placement of the blower hose and the direction of the air output are determined by the shape of the space and the minimum "clear" time before entering the manhole is determined by its size and the blower's output (cfm). (Yeah, I know, more than you wanted to know - happens when you get a technical instructor / course writer involved.)

John

 

[Jeremy Leach]

My 'joke' about robotic selector also had a serious side - because I can see that the simple act of opening the cellar door will be such a major temperature change event that even the most amazing control system won't be able to cope. So improving your temperature stability might have just as much to do with your access frequency/duration etc as the actual control system??

For instance, let's say you go in your cellar twice a day and each time you flood the cellar with warm air that takes 5 minutes to stabilise to 16 degrees again after you leave. Maybe this is so significant that it makes the pursuit of careful monitoring and control pretty pointless?

I'm probably way off here, but just injecting it for consideration

 

[Dippy]

I can see the subject of specific heat capacity of bottles of wine vs Air about to emerge.....

 

[Jeremy Leach]

This explains the background quite well ...
http://www.thewinedoctor.com/advisory/buystoreidealcellar.shtml

Getting the specs/datasheet of the aircon will be the best start I think....

 

[Mycroft2152]

For instance, let's say you go in your cellar twice a day and each time you flood the cellar with warm air that takes 5 minutes to stabilise to 16 degrees again after you leave. Maybe this is so significant that it makes the pursuit of careful monitoring and control pretty pointless?

I'm probably way off here, but just injecting it for consideration

That is why they have double door air-locks.

 

[Dippy]

Blimey, this is getting well OTT and OT.

If this is a normal cellar aren't we getting a little carried away?
Down the stairs, open the door, walk in and close the door.
A waft of warm. Big deal. No great hurricanes.
If there aint too much lag/hysteresis on the thermostats then this can be sorted easily.

At this rate Fritttzz is going to regret ever asking the question!
Good luck mate

 

[Mycroft2152]

Blimey, this is getting well OTT and OT.

If this is a normal cellar aren't we getting a little carried away?
Down the stairs, open the door, walk in and close the door.
A waft of warm. Big deal. No great hurricanes.
If there aint too much lag/hysteresis on the thermostats then this can be sorted easily.

Let's get Nesbit drunk!

 

[slimplynth]

Heat rises, opening the door isn't going to let warm air in.. it will let what little heat is in there, out.

I still think conducting a survey with as many sensors as possible is the best way to start. put a sensor in each corner of the room, one in the middle and some in dummy wine bottles... record for as long as you feel necessary, possibly a constant feature (what I would do)

From the graphs you'd hopefully see that opening the door for seconds possibly many minutes would have very little impact on overall conditions.

Not sure of your picaxe/electronics ability but a datalogger is definitely a good project to start with, plenty of previous threads to research, make it wireless too?

Good luck and let us know how you get on.

Regards

 

[Dippy]

I know that Kwai Chang Caine could walk the rice paper and leave no mark, but I didn't know that Slimplynth can open a door without causing a waft...

 

[kevrus]

Not really relavent to the topic but heat doesn't rise, hot air rises...heat will travel in all directions..warm up a length of steel from the centre and the heat will travel in both directions.

Opening any door or window will cause some air movement hence a change in temp/humidity, however slight. The ice build up in a fridge primarily comes from the moisture removed from the air due to the cooling process. Opening the door allows partial /complete air changes to take place hence more moisture to be condensed out and frozen.

 

[Dippy]

Ah, thanks for info on convection kevrus.

"Opening any door or window will cause some air movement ...."
- not when slimplynth does it

I think frittzz has got fed up and gone off to have a go. I don't bame him.