Jaycar Tempmaster Mk2

[Ade42]

Gday!

After quite a few "stalled" brew's Ive build one of the Jaycar Tempmaster MK2 kits.
Its a fine bit of kit and works quite well (i think...) apart from one annoying feature..

Im using the heating setting at around 18-19C, Ive got my beers in a room that gets the morning sun and heats up to around 23-4C so Ive got the tempmaster set for 19c (is that ok?)

Under the house (queenslander type) It gets cold all day and extra cold at night. so seeing Im now playing with heating belts and 240V "kits" I decided to brew em in the house under a smoke dectector and unplug when I go to work ( hence the warm room).
Sofar all good.. exept at night when the tempaster hits the "heat" temp.

The Relay in the kit chatters to death and keeps me awake, It chatters so much that some times it HUMS very very loudly.. Now ive made the kit to Sepc and double checked all components. I was an electronics Enginner in my previous job so this kit was a peice of piss to build.

Im just wondering if anyone else has had this "problem" I mean I know a thing or two about this and I think the life of this realy won't be very long!

So Im thinking of ditching it and upgrading to a TempMate. IS it worth the extra $$ and is it "silent"?

 

[Cannibal Smurf]

I looked at one of those Jaycar kits... very briefly. Do yourself a favour, go see Ross and get a TempMate ;-)
It heats AND cools, you can leave it on when you're at work and I haven't heard a peep from mine.

edit: typo

 

[LethalCorpse]

hmm...The relay shouldn't chatter - it should turn on and stay on for some time, the worst you should hear being a click each time it cuts in or out, and it shouldn't be doing that any more than once in ten minutes or so. Have you checked the hysteresis settings (I assume the silicon chip article gave some thought to hysteresis)? It will chatter if the hysteresis is too low, or if the temp sensor is too close to the heat source (it should be in the wort or at least touching the side of the fermenter, not on the heat mat or sitting in the bottom of the wort). If you have access to an oscilloscope it might be worth seeing the signal applied to the relay's coil - it's not getting AC instead of DC or anything silly like that is it?

A solid state relay wouldn't make any noise at all, so you could replace it with that, but I'm inclined to think the relay chattering is symptom, not problem.

 

[krusty_oz]

I finished mine yesterday and did some quick tests with it. I found it did the same thing on some instances, mainly when I didn't have the temp probe on the aluminium plate (thus having no 'thermal mass' to smooth out the temperature change).
I'm testing mine some more before connecting the fridge to it as the relay won't last long if it tries to rapidly switch the inductive load of the compressor. If I'm still not happy with it I'll probably swap out recon the 1K2 resistor providing feedback to the comparator with something a little bigger (or even a trimpot for flexability).

How have you got the temperature probe attached to the fermenter and what are you using for the 12V power supply?

 

[Verbyla]

Get a Tempmate and put your brew in a fridge with a heating pad.

You'll never have to do a thing and it'll never let you down!

 

[LethalCorpse]

I'm gonna have to design one and release the circuit, aren't I?

 

[avaneyk]

hmm...The relay shouldn't chatter - it should turn on and stay on for some time, the worst you should hear being a click each time it cuts in or out, and it shouldn't be doing that any more than once in ten minutes or so. Have you checked the hysteresis settings (I assume the silicon chip article gave some thought to hysteresis)? It will chatter if the hysteresis is too low, or if the temp sensor is too close to the heat source (it should be in the wort or at least touching the side of the fermenter, not on the heat mat or sitting in the bottom of the wort). If you have access to an oscilloscope it might be worth seeing the signal applied to the relay's coil - it's not getting AC instead of DC or anything silly like that is it?

A solid state relay wouldn't make any noise at all, so you could replace it with that, but I'm inclined to think the relay chattering is symptom, not problem.

+1 for hysteresis. I've built a similar kit, although when I put mine together it was a temperature switch that could be set to a wide range of temps and I adjusted it to 19degC. Mine has a hysteresis trim pot - surprised your's doesn't. I put another one together for my brother that was from a different kit - designed for controlling a fridge. This one also had a hysteresis pot but I can't remeber what the kit was called (probably tempmaster or something like that)

I've only ever used either of these for cooling, not heating, but they've always worked well once set up. I just set the on temp to 19 and the off temp to 16 for ales.

You can use a digital multimeter to check for ac across the relay - just set to ac volts and the ripple voltage will displayed.

Andrew.

{edit: typo}

 

[shonks69]

Hey All
I built one with not a great deal of success, the controller works fine on the 9v circuit but i can not get it to work on the 240v circuit. has anyone else come across this problem?
I am seriously thinking about cutting my losses and getting a TempMate as I reckon the Tempmaster (if working) would be a pain in the ass to adjust the temp. settings.

Cheers
Shonks

 

[Ade42]

Thanks for the replys..

I have made up the sensor to spec and have it pressed agenst the outside of my wort, in the middle, with a block of white polystyrene foam and a ocky strap.

Bugger there seems to be a bit of AC across the relay.. still the ONLY componet ive replaced/changes is the Pot,
I put a higher 10 turn one in so i could go past 20c.

Whgen I first built it, the "chart" said. the top would be 2.92V. mine only went to 2.78 volts. now im brewing "hotter" than lager so changes the trimpot to a higher value. That can't be it?!?!?!?..

The other oddity is the 1004 Diode in front of the relay.. in the instructions (not the scematics but the "pics") its reversed. I put it in as the printed PCB said. hmmmm..

still thinking of diching the 80$ "kit" and getting the real thing, and no more meters to figure out the temp!

 

[avaneyk]

Bugger there seems to be a bit of AC across the relay.. still the ONLY componet ive replaced/changes is the Pot,
I put a higher 10 turn one in so i could go past 20c.

What are you using for a power supply? I had to build my own - did yours come with an in-built one or are you using a plug pack? Lots of plug packs have a fair amount of ripple on them. I'd suggest getting a dc regulator ic and putting it between your supply and the kit. This will only cost a couple of dollars and will make sure your dc supply is really dc.

The diode across the relay is used to squash the high voltages that occur when the relay switches (impulse caused by magnetic field in the relay forming and collapsing) - this prevents damage to the switching transistor. It should have the cathode (side with the line) towards the positive supply - thats how mine works.

I'd stick with it for a bit longer since your $80 down - once its set up its not that hard to adjust. I've found the calibration data in the kit is a bit out but once you've worked out each temp setting (say 18deg, 12deg and 3deg) its easy to adjust between them...

Hope this helps,
Andrew

 

[LethalCorpse]

Bugger there seems to be a bit of AC across the relay..

Sounds like the problem is in your PSU circuit. Check that you've got the right filter capacitors installed, and that they're around the right way. The regulator Andrew suggested is unlikely to help, but you need to make sure your supply is clean

 

[technocat]

Ade .....you could try a 100uF electro across the coil to increase hysteresis and slow the response time. I diode across the coil is to stop destroying the driver transistor when the voltage collapses in the relay coil. Any ripple on the supply rail would also cause instability in the circuit. Posting a circuit diagram would help.

cheers :icon_cheers:

 

[Ade42]

Ade .....you could try a 100uF electro across the coil to increase hysteresis and slow the response time. I diode across the coil is to stop destroying the driver transistor when the voltage collapses in the relay coil. Any ripple on the supply rail would also cause instability in the circuit. Posting a circuit diagram would help.

cheers :icon_cheers:

Thanks for the tip. Will be trying that out very soon.
There is a circut diagram on this very forum... somewhere! I just cant find it! And have no scanner..

My psu is a regulated 400ma 12VDC plugpack. the kit requires 100ma.. I thought the Regulatted PSU the way to go..


The "chattering" last night was pretty appalling. Its now buzzing quite loudly.

another "fix" I atempted without any results was to replace the "bell wire" to the sensor with standard shielded single core audio cable. though there may be some interferance from a nearby computer. But it was all in vain.

If this helps its the New 2009 Revision.

Ill have another look later for the diagram. Its here somewhere!! and ill post it here

Ill have another close look at the board with a DMM and my trusty anolouge one.

Oh this may help. im only using it for heating and have it set up like this..

I have my probe attached to one wort (with a block of foam and ocky strap) a heating belt on that wort and another heating belt on another wort ( i pitch both worts at the same time) Im still figuraing out a brew that I like so I make 2 at the same time so i can find my "fav" one.

 

[krusty_oz]

Another thing to try - does it chatter if you put the probe between something hot (relay should be off) then something cold (relay should be on), where the hot and cold things are say a cup of hot water and ice.

 

[Ade42]

No it dosent! Its a clean switch. Its only when its "on the wort" it chatters..

secondly. It was chattering it's head off just then and I pulled the Power (for the heater belts) and it was a clean switch, the noise stopped.

Ive also checked and rechecked the components and thier layout with DMM and all is fine?!?!

 

[krusty_oz]

Interesting it stopped when you unplugged the power for the belt, there could be some electromagnetic interference coming from the belts causing the interference to the circuit. I don't have belts so I can't check. I'm away from home for work so I can't do any measurements on my circuit till the weekend.

Another idea comes from when I looked at data from a temperature data logger in my keg fridge a few weeks back. I noticed that the air temperature drops several degrees when the compressor is on but there is less variation on keg temp due to it being a large body. What you see is air temp zig zagging and beer temp doing a gentle ripple.
With this in mind, it may work better having the temp probe close to the belt so the probe measures a wider temperature range (ie gets heated by the belt) instead of trying to pick up the small changes further from the belt. Initially system will turn on and off more but the fermenter will stay at the same temperature.

 

[Gulf]

OK, I'm taking a guess here but from what you describe it's possible that the current draw from the heating belt switching on is causing a momentary voltage drop that affects the temperature control circuit. I've seen something like this on simple circuits I've built myself, despite using regulated plugpacks. Better regulated psu's helped (eg. a computer power supply), but didn't totally eliminate the problem.
I'm assuming you're running a long extension cord under your house, and powering both the heat belt and plug pack off it. As a check, you could run another extension cord for just the heat belt and connect it to a different power point, on a different circuit in your house if possible.

If that eliminates the problem then... hmmm I don't know... :/
You could try reducing the power of the heat belt with a light dimmer switch in series, or somehow try to reduce that voltage drop to the tempmaster, I guess one way would be to hook the tempmaster up to a 12V SLA battery and charger (effectively one bigass capacitor).

 

[technocat]

Yes you could try a line filter to knock out any transients. Your PSU whether it be linear or switchmode design may not be up to the job and as been suggested a 12VDC battery or another PSU could be tried. If you have put this together yourself, check the values of components are correct as per circuit diagram and orientated right way. Get another pair of eyes to check as well. Not trying to tell you how to suck eggs but you would be amazed how the human brain will miss a mistake over and over even with the simplest of circuits. I have looked at a repair late at night which absolutely defied logic and given up in disgust and gone to bed, only to look at it next morning and the fix was that evident that blind freddy couldn't have missed it.

Cheers

 

[Ade42]

Thanks guys, Ill do that tonight..

At the moment the gear is inside and its on a 1m ext cord. Ill use another outlet (in another room on a diff curcit) for the belts and visa versa.
Ill get the GF to reckeck all components.. I agree about a 2nd look.. when I was in the ciema industry (13$ an hour!) and had to repair all manner of electronic gear and built a suprising amout of kits, there would always be the one dud job that you could swear blind that was ok. looking at it while a collegue is checking over with his cro usally did the trick. suddenly that cappy did a polarity swicheroo while you wern't looking..

Ill change the psu as well and tryout a regulator kit inbetween "plugpack" and unit
will get a KC5446 (jaycar) or a k3592 (Dse)
and play around tonight..

Ill also get a 100uf cappy like suggested on another post and thry that as well!

 

[krusty_oz]

An update. I had my Tempmaster start to chatter. Was using a switchmode plugpack PSU so I changed it to an older transformer type. It made some improvement but not enough.
I simulated the circuit in an electronic simulator program and found the circuit was suscpetable to ripple and small transients (fridge compressor turning on or in my case a fluro light on occation).
Substituting a couple of the capacitors in the circuit will help eliminate the problem. I couldn't be arsed pulling it out of the jiffy box so I just did as Beernut suggested and stuck a capacitor (I chose a 16V 1000uF electrolytic) across the relay output terminal block. It now takes about a second for the relay to shut off (after disconnecting power) and it has eliminated the chatter.