# Coolmaster



## recharge (10/1/06)

I have recently built the silicon chip coolmaster which is currently running a chest freezer @12 deg. 
I check it every day and the temp is always spot on. But this evening i could hear a clicking in the brew room and noticed it was the freezer trying to click on. 
I had a look at the coolmaster controller and the led was flashing dimmly and then a little brighter when the freezer was clicking but wouldnt cycle on. 
As soon as i touched the sensor to warm it up a little the freezer started up straight away. 
All that said it obviously is eventually starting the freezer as temp is always spot on but should i be worried about the clicking but not starting. I thought the circuitry was designed to stop this behaviuor.

Thanks to anyone who can help.
Maybe something for others to watch out for

Cheers :beer: 
Richard


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## timmy (10/1/06)

sounds like the hysteresis (deadband) is too narrow. The relay is chattering until the temp gets high enough to keep the contact closed.


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## Simon W (11/1/06)

Thats what I was thinking, I seem to remember the article mentioning how to adjust this, either that or it was in 'Ask Silicon Chip' a few months later.


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## agro (11/1/06)

Assuming the Coolermaster is the same as the Tempmaster... VR2 (5k potentiometer) should adjust the hysterisis of the circuit. I set this to half way and have a .5 degree variance between the fridge turning on and off.

No relay in this circuit so it may be different. It uses a TRIAC (BT137F) to switch the mains.

Agro.


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## recharge (11/1/06)

Not sure if the same(KC5413) but it has a triac as you mentioned.
I have posted this on jaycars forum.
May try adjusting vr2.
The instructions say it is for balancing but give no guidelines except it should be fine in the middle.

I can feel a new hobby coming on tho.

Cheers all for replies

Richard :beer:


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## Simon W (11/1/06)

I'm not so sure now that a narrow band hysteresis is your problem. 

Does your freezer turn off shortly after starting, maybe a second or so? or is it on for a min or so then turns of?
If the later, hysteresis is not your problem.
If its only on for a sec, then turns off, then tries to turn on again, Hysteresis could be/is your problem.

I re-read the article last night.
VR2 is for 'balance', whatever that means! I would have to get the datasheet for the LM311 and nut that one out. I dont have the time right now tho.(Rental inspection tomorrow).
I think the idea of the balance is to adjust the offset voltage between the inverting and non-inverting inputs of the comparator. So instead of the comparator conducting when both inputs are the same voltage, one can be higher/lower than the other.
This would seem to be hysteresis, but it is not. It is just changing the temperature the circuit switches at. Pin 5 of the 'balance' control on the comparator appears to control the voltage seen by the non-inverting input, therefore pin 6 must be for the inverting input. Changing these with VR2 would not give hysteresis. 
However, the text says there is a feedback resistor in the circuit (the 33k) which is connected between the opto and VR2. This resistor creates the hysteresis.
It works by reducing the voltage applied to the pin 5 side of the balance control, and this only happens when the comparator is 'off' (its output is grounding) and therefore the led and opto are on, and so is the fridge/freezer. This means that the non-inverting input voltage is lowered, and the temp preset voltage is lowered.
As soon as the temp sensor reaches this voltage, the comparator turns on(output at +9v), the opto stops conducting(fridge off), so does the feedback resistor, and therefore the balance is returned and the non-inverting input is back to its original user-pre-set temp voltage waiting for the temperature to climb back up to meet it again - hysteresis.

This is confirmed in the Dec '05 issue in the 'Ask Siilicon Chip' on pg 106. 
There is an answer there for chaging hysteresis, and they recommend either increasing the value of the 100R resistor to 150 or so, or reducing the value of the feedback resistor(thereby flowing more current and lowering the balance voltage further) to around 27kohm, or both.

But, if hysteresis isn't your problem, it may be that the power surge/spike from your fridge is triggering the triac. The circuit has some protection against this but maybe it is not enough? I don't know. Im leaning away from this theory tho, because you say that the fridge kicks in as soon as you warm up the sensor.

Hmmm


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## recharge (11/1/06)

Sorry most of that went over my head tho i intend to read it a few more times.
Generally the led flickers for a while at the same time freezer sounds to be trying to click on then after a short time it will start. If i hadnt have heard the clicking i might never have known i had a problem as it eventually kicks in and fermenter in freezer is always spot on 12 deg.

Worse case scenario ill build another one and use this one to run a fan. Bit harder to stuff a fan i would guess.

Anyway thanks again.


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## stephen (12/1/06)

Simon W said:


> I'm not so sure now that a narrow band hysteresis is your problem.
> 
> Does your freezer turn off shortly after starting, maybe a second or so? or is it on for a min or so then turns of?
> If the later, hysteresis is not your problem.
> ...




Simon

Any chance you could post the circuit diagram or scan it and pm me. This sounds similar to a schmitt trigger type circuit operation. They can also have a serious hysteresis problem if not designed correctly.

Steve


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## Simon W (12/1/06)

Recharge, try something for me: unplug the fridge while its off and before the LED starts flashing. Then sit and wait for the circuit to cut in.
See if the LED flickers with the fridge unplugged or turns on full brightness straight away. This will help me eliminate one half or the other of the circuit.
Don't forget to plug the fridge back in 
If Bakers Hill wasn't so far away I'd drive up there and probe its innards!


Stephen, you are correct, thats exactly what it is. But I assume Jim Rowe(a very competent designer) has used a comparator(LM311) instead of a schmitt trigger IC because such IC's only have approx 0.8v 'backlash', whereas this circuit is adjustable.

The circuit wasn't available on the Silicon Chip website, I'll have to scan it tonight.

Simo


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## recharge (12/1/06)

Will do that tomorrow.
Watched it for 5 mins today trying to start up.

Cheers guys


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## Simon W (13/1/06)

Thanks Recharge.
I noticed no-one at Jaycar has replied to you yet, nice of 'em eh?
I'll see if I can track down Jim Rowe's email address.

BTW, Jim Rowe is kinda famous.....
"For the record Jim Rowe did not design the Microbee although he did join
the company for a short time around 1986. Jim did design EDUC 8 (1979 or
so) and legend has it that Jim's computer was probably the first
hobby-built PC in the world! It was published in Electronics Australia
just prior to the MITS Altair article appeared in Popular Electronics
the US. The editors of Popular Electronics did later admit, reluctantly,
that EA had published the first home PC design. " - Owen Hill.

Cool huh? Remember the Microbee? I think every school in Australia had them, and they were very popular right around the world, esp in Europe, before the IBM clones reigned supreme. Owen Hill was the designer-owner of Microbee Computers.


Stephen:







EDIT: ahhhh hello? Image?.... ahh there you are.


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## stephen (13/1/06)

stephen said:


> Simon W said:
> 
> 
> > I'm not so sure now that a narrow band hysteresis is your problem.
> ...




Just had a good look at the circuit. the LM311 is basically an OPAMP being run pretty well in saturation mode, ie. If one was to feed an audio signal into the input, the output would only switch between a high state and a low state or vice versa with no amplification of the original signal. VR2, the balance resistor sets the "gain" of the OPAMP which, in effect sets the hysteresis - the difference between the switch/switch off voltage or in this case when the temperatures when the fridge/freezer should be turning on and off. VR1 purely sets the voltage to be compared by the LM311 from the temp sensor through TS1 and the 10k resistor. So the area I would be looking at would be VR2 that sets the difference between the switch on/switch off temps.

If you have any further questions feel free to pm me or just place in the forum so we all can learn.

Regards

Steve

Disclaimer - I am relying knowledge I was taught in my technician course almost 25 years ago.


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## recharge (14/1/06)

Ok i had the plug out today and waited hours for it to turn led on (ambient temp in brew room currently 15 freezer set at 12) so decided to do a brew while waiting. What else !! 
Anyway back to the point. I didnt see it turn on but it was off one sec and on about 10 secs later when i looked, it doesnt do this when freezer is plugged in. 
I also tried holding sensor in the air by the wire so as not to put any rapid heat into sensor, definately cycled in properly with or without plug in on these occasions. 
Any idea which way to turn vr2 and by how much or will this just be a trial and error jobby.

Thanks again

Richard


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## stephen (14/1/06)

recharge said:


> Ok i had the plug out today and waited hours for it to turn led on (ambient temp in brew room currently 15 freezer set at 12) so decided to do a brew while waiting. What else !!
> Anyway back to the point. I didnt see it turn on but it was off one sec and on about 10 secs later when i looked, it doesnt do this when freezer is plugged in.
> I also tried holding sensor in the air by the wire so as not to put any rapid heat into sensor, definately cycled in properly with or without plug in on these occasions.
> Any idea which way to turn vr2 and by how much or will this just be a trial and error jobby.
> ...



Richard

Unfortunately the next couple of days/weeks are going to drive you insane. Not knowing the qualities of all the componants in the circuit I can't calculate an answer - and I no longer have my study notes to refer to. My suggestion to you is to set it mid way, make sure you fridge is full of cold beers and watch what happens and then make minor (approx one clock hour adjustment) and see what happens from there. If it is still having fun and games I'd probably start looking also at IC2 - the MOC3021 - it looks like an opto coupled Diac to switch on the Triac - BT137F.

Any questions please feel free to ask. If it all gets to hard take it back to where you got it from - there may have been a defective componant supplied with the kit.

Have fun

Steve


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## recharge (14/1/06)

Im gonna buy another one tomorrow as i want one to run a cooling fan anyway. 
In the mean time i will have a play with vr2 see if i can settle it down. I 

I was more concerned really with whether it would damage my freezer compressor, hate to wreck a good freebie.

Cheers :beer: 

Richard


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## stephen (14/1/06)

Hey Recharge

How much are these kits worth?

Steve


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## recharge (14/1/06)

$39.00


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## agro (14/1/06)

Don't underestimate the value of a lump of ice and your hand. I used some ice in a cooler, a thermometer and the head from my hand to test the one I built and to calibrate an external knob so I could more easily adjust the temperature.

Makes it real easy to vary the temp quickly, and you should see the LED turn on and off reliably at the threshold temp. Just don't leave the AC plugged while your playing...

Jason.


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## recharge (14/1/06)

Agro
It definately has no probs with rapid temp change as you describe i was just holding it against the cooling coil of freezer or in my hand, works fine. Seems to be a prob at the very slow rate my chest freezer increses in temp. 

No biggie cuts in eventually

Cheers
Richard


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## 2es (16/1/06)

I've been fiddling now for a week.Blown 4 triacs and solved the problem with a exhaust fan.Must be working as a spike control.Now have the problem of cutting in and out over 1/2 degree.Have had 3 new lm311s still the same .Pin5 voltage 8.79v pin6 8.91v .Will try tomorrow 150 ohm resistor.Jaycar only sells the produce but has no service after.


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## vlbaby (16/1/06)

recharge,
I think your problem is not hystersis. The circuit has clearly had a set level of hysteresis designed into it already ie 33k resistor.
I think you'll find that the fridge itself, being an inductive load, is causing a power supply spike that is reflecting into the mains and into your little circuit. One easy way of confirming this would be to connect the circuit to a simple incandescent light bulb. The light bulb is a resistive load and wont induce any spikes at all. 
Try heating up the sensor slowing and see if your light bulb flutters as it switches on, my bet is it wont.
If i'm right, then the only way to stop this is either fit a supressor to the fridge, or better line filtration to your circuit.
My own temperature controller i built suffers a similar problem of which i am to fix one day. My march pump starting is enough to set mine off crazy.

hope this doesnt confuse things more <_<


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## Uncle Fester (16/1/06)

> ambient temp in brew room currently 15 freezer set at 12)
> [\quote]
> 
> Ok you got me curious...
> ...


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## recharge (17/1/06)

mandrakar said:


> > ambient temp in brew room currently 15 freezer set at 12)
> > [\quote]
> >
> > Ok you got me curious...
> ...


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## recharge (17/1/06)

vlbaby said:


> recharge,
> I think your problem is not hystersis. The circuit has clearly had a set level of hysteresis designed into it already ie 33k resistor.
> I think you'll find that the fridge itself, being an inductive load, is causing a power supply spike that is reflecting into the mains and into your little circuit. One easy way of confirming this would be to connect the circuit to a simple incandescent light bulb. The light bulb is a resistive load and wont induce any spikes at all.
> Try heating up the sensor slowing and see if your light bulb flutters as it switches on, my bet is it wont.
> ...


Thanks for reply vlbaby
I will still try with a fan or light globe to see.
Any more info on a supressor or line filter or if you could point me in right direction would be appreciated

Cheers
:beer: 
Richard


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## recharge (17/1/06)

2es said:


> I've been fiddling now for a week.Blown 4 triacs and solved the problem with a exhaust fan.Must be working as a spike control.Now have the problem of cutting in and out over 1/2 degree.Have had 3 new lm311s still the same .Pin5 voltage 8.79v pin6 8.91v .Will try tomorrow 150 ohm resistor.Jaycar only sells the produce but has no service after.
> [post="102883"][/post]​




Jaycars forum aint much chop either
:beer: 
Richard


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## spambait (17/1/06)

recharge said:


> I have recently built the silicon chip coolmaster which is currently running a chest freezer @12 deg.
> I check it every day and the temp is always spot on. But this evening i could hear a clicking in the brew room and noticed it was the freezer trying to click on.
> I had a look at the coolmaster controller and the led was flashing dimmly and then a little brighter when the freezer was clicking but wouldnt cycle on.
> As soon as i touched the sensor to warm it up a little the freezer started up straight away.




I'm no Electronics expert... Just a guy who can read a circuit diagram well enough to be dangerous with a soldering iron  

I built this kit about 6 weeks ago and haven't really had any problems with it apart from working out how to set the thing to run the fridge at the temperature that I want. One thing I did notice was that I would get some funny results when I started mucking about with the the multiturn trimpot while it was plugged in to the fridge. I also tried testing the thing out with a light turned on, and found that the cooler master would act a little like a dimmer switch when I turned the trimpot up and down just past the point where the hysteresis comes into effect.

Another thing worth mentioning is that I have a a friend who is an electronics engineer who built his own controller based on this circuit, but replaced the optocoupler and the mains part of the circuit with a solid state relay. The interesting thing is that this device caused my fridge to make a funny chattering sound, but failed to allow the compressor to fire up. His explanation was that the while the fridge's running current is quite low, the draw-down current is quite high (blew a 3Amp fuse in his circuit), and his relay must have had some sort of protection circuit built-in. 

Even more interesting though was that the Coolermaster worked fine. Two things that I noticed though... first was that I needed to give it a slightly wider setting for the hysteresis (can't remember which way to turn VR2) because the fridge would sometimes behave like it did with my friend's controller. The second thing was that I had to ensure I had given the curcuit enough power to do the job, but not so much that it would cause any of the capacitors to start smoking. I'm running the Coolermaster off a 12v regulated plugpack rated at 1Amp. I found that my other unregulated plugpack pushed too much power into the circuit (had to replace that monster 2200f cap due to burning it out), and a 9v supply was too weak to drive the 7809. The other thing I did was to make sure that the temperature sensor was fully sealed against moisture (does funny things if you touch the LM335Z's pins with damp hands!!) and to place the sensor against the fermentor so that the brew temperature would be measured rather than just the fridge - I got a mate to make up a nice little copper plate with the sensor attached that I can mould to the shape of the fermenter, which replaces that aluminium block that came with the kit). Brew temp will change more slowly than the air in the fridge, meaning that the controller won't try and turn the fridge on more often than it needs to.

Like I said, I'm no expert. Just thought it might be nice to share the experiences as it were. I've got the controller running with about 50 litres of pilsner, maintaining a perfect 11C... just try doing that without the fridge in a Melbourne summer !!!

Working with this controller has given me a second obsession... now it's Beer AND Electronics (My missus is going to kill me!). I'm now working on a microcontroller based circuit that will allow me to heat as well as chill, and with a selectable temperature and hysteresis... Got most of the parts and I've written the software, and I'll post the design and code once it's finished.

Salut.

S.


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## Simon W (17/1/06)

Recharge, *DO NOT* adjust VR2. It DOES NOT adjust the hysteresis. All it will do is change the temperature(very slightly) that you spent lots of time getting VR1 spot-on 12 degree's!



> I think your problem is not hystersis. The circuit has clearly had a set level of hysteresis designed into it already ie 33k resistor.
> I think you'll find that the fridge itself, being an inductive load, is causing a power supply spike that is reflecting into the mains and into your little circuit. One easy way of confirming this would be to connect the circuit to a simple incandescent light bulb. The light bulb is a resistive load and wont induce any spikes at all.


Yep, exactly. I suggested unplugging the fridge to see what happens.
The fact that the circuit does not behave the same when the fridge is unplugged, proves hysteresis is not the problem here.

I suspect the surge current from the fridge motor may be switching the triac off, then the triac tries to switch on again and so on. MAYBE. This problem is mentioned in the article, and protection is provided. I suspect this protection may not be enough for your fridge. But can't say for sure.
A more unlikely theory, there might be noise generated by the fridge motor that the temp sensor is picking up and triggering the circuit. The comparator is comparing very small voltages, a swing of no more than 10 or 20 _thousandths_ of a volt, any noise induced in the very long sensor lead(acting like an antenna) could quite easily be this large. You may need to shield the sensor wire somehow, or even buy two-core screened cable(approx 80c/metre at Jaycar catWB-1504).
When I got that issue of SC and read the article, I was surprised at the long length of unshielded cable.
Having said that, I don't know exactly what's happening, but It's more likely to be the triac and surge.


Stephen, 
I just read the datasheet for the LM311, and it confirms my circuit analysis a few posts back.
The 33k feedback resistor generates the hysteresis, not VR2.
The inputs at pins5 and 6 are an 'offset ballance'. This means that the comparator will trigger when the pin 2+3 inputs are of a different voltage, as determined by pins 5+6. This is not hysteresis. If the 33k resistor is not in the circuit, the offset is still there, but the hysteresis is gone, the circuit will turn on at say, 12degree's, and turn off at 12degree's... oscillation.
The 33k resistor is changing the offset only when the fridge is on and cooling.
Adjusting VR2 will change the temperature the circuit triggers at, but will not change the hysteresis bandwidth.
It seems that VR2 is only included here because this is a copy of an example circuit provided by National Semiconductor in their datasheet, not the whole circuit, just the support componentts for the comparator.
According to the datasheet, a 5k VR2, fed by a 3k resistor will only adjust the offset by approx 8mV, this is a span of around 0.8 degree's! A handy 'trimming' 

Simo


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## recharge (17/1/06)

Well i bought a new one today though now it is called a Tempmaster, it has a slight design change allowing you to set up for heating OR cooling. 
I will add a couple of small switches i think to enable the change. 
I will also add an rca plug wired to pin 4 and point b in the link position to measure set voltage from outside the case. (maybe a little screwdriver epoxy'd to vr1 for easy adjustment.
Anyway i will see if this one does the same when finished. (Next night shift)

Cheers for now :beer: 

Richard

PS i run it with a 400mA plugpack


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## stephen (17/1/06)

Simon W said:


> Recharge, *DO NOT* adjust VR2. It DOES NOT adjust the hysteresis. All it will do is change the temperature(very slightly) that you spent lots of time getting VR1 spot-on 12 degree's!
> 
> 
> 
> ...



Simo

I stand corrected. I did not have the luxury of any datasheets or the circuit analysis. I was relying on my memory remembering circuit theory taught to me nearly 25 years ago as a trainee Radio Technician in the RAAF. From what I have learnt from this forum is that I will do away with the Triac and IC2 and the 240V side and look at a low current relay between the 100 ohm resistor and LED1 to switch my fridge on and off. I may have to recalculate the value of a replacement for the 100 ohm resistor dependant on the current draw of the relay coil.

Regards and beers

Steve

BTW TRIAC1 is only rated at 8 amps - the switch on current draw of a compressor can easily exceed this, though for a brief momentr


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## stephen (17/1/06)

To add further to the above, if you suspect any interferance from external sources messing up your signal from the sensor, just wrap the lead with alfoil for the entire length of the sensor lead, leaving only the sensor exposed and link the end with the earth, say pin 4 or 1 of IC1 and see how it performs. The alfoil only has to cover the lead, ie. a strip about 1-1.5" wide and wrapped completely around the lead is more than ample. You may have to use multiple strips to achieve this.

More beer to drink

Steve


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## recharge (17/1/06)

Stephen,
Could you post your mods when finished and let us know how they go.
Cheers

Maybe we should start another thread just for modifications as there are others posted in different threads, we could get them all in one place for future reference/users.

Cheers all 
:beer: 

Richard


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## stephen (17/1/06)

Recharge

More than happy to post any "mutilation" I do to any project that I do, however, I hope that when I do post them that anyone reading them and trying to emulate me does so on their own back. I will not be held responsible for any "oops!" (My disclaimer)

Steve


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## recharge (17/1/06)

Stephen,
I would like to think that would go without saying, but you never know i guess, best to cover your ass.
As for me i can put things together and tho i dont understand it all i know that 240 volts hurts.
As for stuffing one up well at 39 bucks i think they were designed for us to play with, im already learning stuff just from this one kit. This electronics stuff is pretty cool, why didnt i pay more attention in school.

Thanks again for your input

Cheers :beer: 

Richard


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## Simon W (17/1/06)

Ooh yeah, 240v hurts like hell, and a good jolt leaves you well shaken up for a day or two. One thing I've noticed is that you realise how stupid whatever it was you were doing was AFTER you did it....... 'I'll just adjust thaBZZZZZT!!'
Electronics is great fun, I've been playing with it since I was 6, but the main thing I've learnt after doing 3 years of electronic engineering at TAFE, this is definatelly one of those things where the _more_ you learn, the _less_ you know! It can get rather frustrating at times! Ohm's law helps ya get through most things though.

Stephen, great idea with the alfoil. I'm not entirely comfortable that the sensor would be picking up noise, as the capacitor across the comparator's inputs will short any AC, but a transient would probably get through. Alfoil is a cheap way of eleminating this possible cause tho. Nice.


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## stephen (17/1/06)

Simon

I am very familiar with the "kiss" of 240V. 

The foil "fix" I suggested will only work if all pieces are joined together to ensure continuity. If this proves to be the fix then I suggest, like you said, to use some shielded, insulated pair cable (twisted will suffice) with the sheild connected to circuit earth, ie. pins 1 or 4. 

I think that if this a problem, I would look at, "Is there another fridge, freezer, clothes dryer etc" nearby that could be inducing the false signals.

For those out there that probably don't know what I'm talking about, I apologise. For those you who learnt something, then I have taught. For those of you who want to know more, feel free to ask and I wiil endeavour to answer your questions as best I can.

More Beer

Steve


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## recharge (18/1/06)

Well it definately isnt picking up interference from another appliance as my brew room is about 50+ meters from any other fridge etc.
Might try making a new sensor with some cat5 being twisted pairs i think it should suffice and would fit better into provided plugs etc. Might be a bugger to get under the seal.

Might look into building a digital thermometer next, a little mini project to pass some quality time at work.

And yes i know the sting of 240v too [ "I thought you switched that fu#$%r off"] always check myself now.

I have a mate who is an electrician who once told me that a little knowledge is far more dangerous than none at all. 

Richard


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## Simon W (18/1/06)

Actually, I was thinking of possible noise from _the_ fridge, as the motor tries to start up 
It's a long shot, but it's another thing we can try to eliminate.
the more things we know it's not, the more likely we are of finding the real culprit, but my money is still on the triac false triggering.

Simo


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## recharge (28/1/06)

Ok built a second unit and it does the same as the first. Starting to think they're a peice of crap.

I got to watch it do its thing a couple of times today and they both flicker etc even with nothing plugged in so i assume this would rule out the freezer being the problem.

I did make a few small additions to the second unit so i can switch it between heat and cool option and also read set and fridge temps(voltage) via an rca plug that goes to my DMM.

Oh well they do at least work 

Richard :angry:


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## ruserious (28/1/06)

Simon W said:


> Ooh yeah, 240v hurts like hell, and a good jolt leaves you well shaken up for a day or two.
> [post="103134"][/post]​



i got a zzzzzap off 415V once at work. (Air Arc Gouger).

gave me heart palps for two days.

gggood nnow thoughhhh....... :blink: :blink: :blink: 

be careful.

imserious


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## recharge (29/1/06)

> i got a zzzzzap off 415V once at work



Dont be doin that again in a hurry  

:beer:
Richard


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## vlbaby (29/1/06)

recharge said:


> Ok built a second unit and it does the same as the first. Starting to think they're a peice of crap.
> 
> I got to watch it do its thing a couple of times today and they both flicker etc even with nothing plugged in so i assume this would rule out the freezer being the problem.
> 
> ...



you get some major points for persistance recharge. Seems strange that your still having probs even with no load connected. How do you know it is flickering with no load connected? 
Is it possible that your 12V supply your using is the cause? Maybe you should try it with a battery supply to see what the result is.

VL.


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## recharge (29/1/06)

vlbaby said:


> recharge said:
> 
> 
> > Ok built a second unit and it does the same as the first. Starting to think they're a peice of crap.
> ...


It has a red led which shows when it is on.
Did have thoughts about power supply today may try another.

Cheers 
Richard


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## muga (29/1/06)

I use these in my chest freezer and two fermenting fridges and don't have any problem, just made it like the kit said and they work fine.


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## recharge (29/1/06)

muga said:


> I use these in my chest freezer and two fermenting fridges and don't have any problem, just made it like the kit said and they work fine.
> [post="105209"][/post]​


But have you watched and or listened as they turn on?
As i mentioned earlier mine work but click in and out for a while before finally starting freezer.


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## Screwtop (29/1/06)

Muga, would seriously be looking at the 12Vdc supply. Not the voltage as this is regulated internally but the waveshape. Try a car battery (nice smooth 12V), see what happens.

Cheers


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## recharge (29/1/06)

any chance a car battery would burn one out??


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## stephen (29/1/06)

recharge said:


> any chance a car battery would burn one out??
> [post="105383"][/post]​


Recharge

The simple answer is no. A fully charged car battery is actually 14.4 vdc which, if memory serves me correctly, is within the input voltage range of the voltage reg - REG1 7809. Diode D1, 1N4004 is quite a robust bit of kit - 400v reverse polarity and can handle 1 amp so wont be a problem: These are often used in high voltage power supplies (200-300 v) for that very reason.

If you are still blowing these little babies up then I would look at the TRIAC1, BT 137F. These are rated at 8 amps. The switch on current of the compressor in your fridge/freezer will momentarily exceed this rating - normally this should not be a problem as the current spike is too short (time wise) to do any damage. If you have an old fridge or freezer These may take a little longer to start up and the current spike is long enough to do some roasting of TRIACs. If this the case you may want to substitute it with a higher rated triac - SC151D. This little beauty is rated at 15 amps! If you do substitute then make sure you check the pin configuration and the case design. These may not conveniently replace the existing Triac: eg. The mounting tab of the original Triac is not connected to any of the pins so this makes it simple to mount to a heatsink. The replacement I have suggested appears to have the mounting tab connected to one of the pins so should be isolated (electrically) from the heatsink. If in doubt or not sure what to do -

DON'T TOUCH A THING - THIS IS THE 240V SIDE OF THE CIRCUIT AND THESE VOLTAGES CAN CAUSE DEATH AND/OR SEVERE DAMAGE IF NOT TREATED PROPERLY!!!


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## recharge (30/1/06)

stephen said:


> recharge said:
> 
> 
> > any chance a car battery would burn one out??
> ...


Stephen i havent blown any up, they both work but are having the same problems as in original post. They both do it even with freezer unplugged. My major concern is long term effect this jittery(for want of a better description)starting will have on freezer. Have decided anyway to go for a Tobins type thermostat as discussed in other threads. And use jaycar ones for running fans for aircooling ales etc.

Cheers
:beer: 
Richard


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## stephen (30/1/06)

recharge said:


> stephen said:
> 
> 
> > recharge said:
> ...


Recharge

I guess I'll have to wait until I pruchase one and have a play before I can provide a definitive answer. So far all my theorising has been based soley on the circuit diagram and a bit of reverse engineering. 

Until I buy my Coolmaster and tinker with it I can't provode any more answers.

Steve


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## recharge (30/1/06)

cheers stephen.
They call it a tempmaster now, same part number though.


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## stephen (30/1/06)

recharge said:


> cheers stephen.
> They call it a tempmaster now, same part number though.
> [post="105392"][/post]​


Always moving the goslposts!!! Damn it!


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## recharge (30/1/06)

Fingers crossed i can put this thread to bed now.

Changed power supply to 9vAC 1000mA today and seems to have fixed problem, i watched it switch on cleanly 3 times today.

Heres hoping.

Cheers all
:beer: 

Richard


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## Simon W (30/1/06)

Well there you go. Well done Richard!

I had considered the power supply, but decided the circuit had ample supply filtering with the two stiffening caps.

Now I'm sorry I didn't mention it.  
Call me nasty names if you want


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## recharge (31/1/06)

Would never call you nasty names Simon, your input was valued and whilst i dont understand it all i learned a few things along the way. Thank you and all others who replied

Cheers 

Richard


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## recharge (13/3/06)

Thought i'd post an update.

OK here's the deal - two different controllers, two different chest freezers sometimes they switch on cleanly sometimes they dont. 
I think the 9v ac 1 amp power supply is better than the 12v dc 300mA one i was using previously.
I spoke to a fridge shop who says the prob with a lot of digital conrollers is they dont give the freezer enough off time, this sorta fits my probs.

So my verdict = dont waste your money on this controller for a chest freezer (just my opinion based on my experience)
Bought two Tobins during the week from All Controls (thanks Chilla) perfect!!

They wont go to waste as i'll now use them to drive pumps for my future jacketed fermenters.

Many thanks again to all who tried to help.

Cheers :beer: 

Richard


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## Tony M (14/3/06)

There is no reason I know to have your fridge operating in a narrow +or- 0.5C band if you only wish to hold the fermentor at 12C. The thermal mass of the beer is so great that the air temp around it could cycle several degrees without any measurable temperature fluctuation in the fermentor. The same applies to keg storage. 
If you set the hysterisis wide, the compressor will be much happier as it will get a decent run.


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## recharge (17/3/06)

Tony M said:


> There is no reason I know to have your fridge operating in a narrow +or- 0.5C band if you only wish to hold the fermentor at 12C. The thermal mass of the beer is so great that the air temp around it could cycle several degrees without any measurable temperature fluctuation in the fermentor. The same applies to keg storage.
> If you set the hysterisis wide, the compressor will be much happier as it will get a decent run.
> [post="114289"][/post]​


I agree tony but although i can solder and built the kit, i believe the hysterisis is preset and i wouldnt know how to work out values to change it.

Cheers

Richard


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## thunderleg (19/3/06)

I built one of these Tempmaster units. It was working fine and I was really happy with it for about a month. Then it just crapped out. The fridge got really cold and was running even when the LED on the unit was extinguished. A few probes with the multi-meter (AC unplugged) shows that the DC side is working fine, but the AC side just wants to power up the fridge all the time. :angry:


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## vlbaby (19/3/06)

thunderleg said:


> I built one of these Tempmaster units. It was working fine and I was really happy with it for about a month. Then it just crapped out. The fridge got really cold and was running even when the LED on the unit was extinguished. A few probes with the multi-meter (AC unplugged) shows that the DC side is working fine, but the AC side just wants to power up the fridge all the time. :angry:
> [post="115237"][/post]​


Sounds like you've blown up the triac in the circuit. Dickie smith will sell you a new one.
vl.


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## 2es (2/4/06)

I blew several triacs solved problem with extra fan across fridge lead.Had false operation when working in shed grinding etc so fitted 4700mfd capacitor across sensor to flatten out spikes.Seams to work now.


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## thunderleg (4/4/06)

vlbaby said:


> thunderleg said:
> 
> 
> > I built one of these Tempmaster units. It was working fine and I was really happy with it for about a month. Then it just crapped out. The fridge got really cold and was running even when the LED on the unit was extinguished. A few probes with the multi-meter (AC unplugged) shows that the DC side is working fine, but the AC side just wants to power up the fridge all the time. :angry:
> ...



I just bought an mtc2120 coolroom controller, so I don't think I'll bother repairing the Coolmaster. The mtc was $41 delivered to my door. $1 more than the Jaycar unit and I:

1. didn't have to go anywhere to get it.
2. don't need an additional DC power supply for it
3. can adjust it easily
4. can see what temp the fridge is at
5. don't have to build it from a bag of components.


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## 2es (29/4/06)

Thermostat sounds OK.Do you have any pics or where did you get it from?


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## jeremy (29/8/06)

Hey all,

Sorry to drag up an old topic but I have purchased this kit from Jaycar and assembled it. POSITIVE I have done it all right, but cant get the thing to work. Can anyone suggest what I may have done wrong? What is a common mistake?

I haven't got anything plugged into the power socket in the side of the case, as I assume this is only needed for testing the circuit, is this correct? Or does this also need to be plugged in?

A couple of concerns I have at the moment are that I may have cooked the temp sensor when I did my heatshrink with a cigarette lighter, or buggered one of my capacitors as I initially had it soldered in the wrong way round.

Can anyone help me out? Thing cost me $40 and I would love to get it to work! Any suggestions of how to test it?

It seems to be sometimes on and sometimes off, but can initiate a change by holding ice to the sensor etc.


Thanks.

Jeremy.


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## chimera (29/8/06)

I can try to be of assistance jeremy.

Problem with that sort of thing is that it tends to require a whole lot more specialised equipment & understanding to test these things than it does to make/break them..

If you're anywhere around Melb I can offer my assistance, PM me if you like


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## jeremy (29/8/06)

It's alive!

After writing my post, and reading over it I thought, maybe it is the socket on the side of the case. The instructions only refer to this when they mention testing the circuit, but they dont say it DOESNT need to be plugged in. Bought a 12V power pack, and now its working.

Thanks very much Chimera for offering assistance!

Another question though, does anyone know how cold it can be set to? The instructions imply that 4 deg is the coldest, and in another place it kinda suggests you can set it to 0 deg. I intend to use this to convert a freezer into a keg dispensing machine so around 1-2deg would suit my purpose. The instructions on the front of the pack suggest that the unit can be used to turn a freezer into a fridge, and this is part of the reason why I bought it!

If it cant go colder than 4, is there any simple way to change the circuit such that it can?

Thanks again,

Jeremy.


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## chimera (30/8/06)

Once again jeremy, there appears to be numerous sources where people have modified the circuit to add an external temperature selector, or to modify some of the circuitry to change the range of the controller

Gald to hear you got it going Jeremy


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## alexbrand (25/11/07)

G'day mates!

Does anyone of you have a copy of this article? I am interested in reading it.

Alex


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## Simon W (26/11/07)

Most public libraries have Silicon Chip.
June '05 issue.


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## Doogiechap (26/11/07)

Simon W said:


> Most public libraries have Silicon Chip.
> June '05 issue.


Including ones in Germany bloke ?
:lol:


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## Simon W (26/11/07)

Good point, sorry Alex.
_Maybe_ a Technical College or University library has it? It's a popular magazine worldwide.
I have the mag but don't have a flatbed scanner.


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## geoff_tewierik (26/11/07)

Got a digital camera? Take a shot of the page at Hi-Res and upload it somewhere.


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## alexbrand (26/11/07)

Simon W said:


> Good point, sorry Alex.
> _Maybe_ a Technical College or University library has it? It's a popular magazine worldwide.
> I have the mag but don't have a flatbed scanner.



Well, I searched our uni lib for this magazine, but it is not listed. Not printed, not electronic. :-(

So that you have this issue at home is a good beginning... 

Alex


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## Simon W (26/11/07)

EPE (Everyday Practical Electronics - UK publication) is basically a clone of Silicon Chip, but a search of their online version doesn't show a hit for the Coolmaster.

Will have a go photographing but have never had much joy before with glossy paper.
Stay tuned....


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## Simon W (26/11/07)

Alex, check your PM
The photo's were a bit tricky, they are a bit blurry in places but should do.


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## alexbrand (26/11/07)

Simon W said:


> Alex, check your PM
> The photo's were a bit tricky, they are a bit blurry in places but should do.



Thx for ur help!!! 

Alex


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## geoff_tewierik (26/11/07)

Simon, care to shoot me a PM of the pics too? Be interested in reading the article as well.

Cheers,

GT


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## Simon W (26/11/07)

For Australian readers, I refer you to Post#68

I don't want to push my luck with the copyright laws.... especially considering the Editor wrote a column sometime last year(?) about it.
Back-issues and Photocopies of the article are available from Silicon Chip for $8.80(from memory)


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