Silicon Chip Coolmaster Temp Controller

[agro]

Made up the Coolmaster temp controller from silicon chip

http://www.siliconchip.com.au/cms/A_104576/article.html

The kit can be bought from Jaycar among others for $39 and it takes approx 1 hour to assemble. I modded the kit to add an external temperature adjustment (*Very* simple mod) and I couldn't be happier.

I believe a number of people on this forum are already using the jaycar kit.

Anyhow... end of my parade

Cheers
Agro.

 

[muga]

I have got several of them for my fermenting fridges and chest freezer.. would be intrested in how you did the external temp adjustment, it's a pain to get it set right.

 

[agro]

Simply a matter of replacing the 500 ohm trimpot with a case mounted pot. In this case I picked up a 1K pot from dick smith and wired in parallel with a 1k resistor to give me a 500ohm resistance through the pot.

The paper is for marking the various temps. This first cut hack is a little more sensitive than I would ideally like, the next generation will have a range switch and a smaller pot so it is a little less sensitive.

In terms of calibration you can either measure the voltage across pins 2 and 4 on the LM311 using the temperature chart provided with the kit - or as I do sit beside the fridge for a little while noting where the controller turns on and off at a selected temperature.

 

[recharge]

So does the external dial only move that small distance or make full rotations first like the original trimpot. Mine is about a full turn for each .1 volt.

cheers
:beer:

 

[Chilled]

Agro

Been looking for the kit on the Jaycar website but it's not too user friendly if you don't have the kit#. Did searches on 'coolmaster' 'controllers' 'temperature' etc etc and ended up having to search through the Kits section. But I couldn't find it in the 179 kits listed!

Do you have a kit# for it?

 

[muga]

Chilled,

KC5413 is the kit number, it's under 'wine cooler'.

 

[agro]

I get a full rotation on the dial, although for some reason I can not yet fathom the action isn't linear.

I will be getting a second kit for experimenting as I would like the temperature range I want (2-30 degrees) spread fairly linearly over the full rotation of the dial. The kit can be wired for both cooling and heating applications, a dual pole switch should make the heating/cooling function selectable.

I am even considering moving to a 20 position rotary switch using resistors for preset temperatures. This would be far more accurate.

For now this does the job.

The kit number is KC5413 - Tempmaster Temp Controller.

Note - there is an additional 2.2k resister in the kit, this is an error. Don't panic when you have one left over.

Agro.

 

[recharge]

I panicked about most of the resistors including the spare one, evetually found out about spare resistor on silicon chip website.I think im going colour blindtho I wish i had a multimeter with me when i was building it to double check all the values as some of the colours looked the same like brown and red. Easy enough to build tho and ive never done much electronics beore.

 

[Joel]

Agro, you won't get a linear response from your psuedo-500ohm pot. The voltage divider network you've created gives a kind of upside down logarithmic response. ie. when you set the 1k pot to half way you'll get 333ohms from the network rather than 250ohms as from a straight 500ohm pot.

As for getting a 2 - 30 degree temp range that should be an easy matter of modifying the voltage divider network reference on the other input pin of the comparator.

 

[vlbaby]

I get a full rotation on the dial, although for some reason I can not yet fathom the action isn't linear.

[post="100317"][/post]​

agro,
when you wire a fixed resistor in parallel with a pot, the action will no longer be linear. I think its hyperbolic or something from memory. You'll need to buy a 500 ohm pot if your to keep it linear.


vlbaby.


oops joel beat me to it.

 

[altstart]

:beer:
Hi people
I posted the following mod for the Jaycar wine cooler previosly.

Gooday people
I have made a simple modification to the Jaycar Temp controller to make it easier to change the set point for different fermentation temps.

First Disconnect from mains voltage.

Step1 replace the 3K resistor that is in series with the 500 0hm trimpot with a2.6kohm resistor. Step 2 remove the 500 ohm trimpot and connect two leads to the circuit board from the the connection points that held the trimpot. Run the leads to a point in the case where you can safely mount a 10 turn 1k ohm potentionometer. Step 3 take two leads from the set points as described in the instructions and route this lead to a socket mounted in the case. Step 4 make up a short lead with a suitable plug and two banana plugs to plug into your meter.
Before closeing case make sure that nothing you added will come in contact with the circuit board in particular pay close attention to the 240volt section.
The 10 turn Ikohm pot is available from RS spares Cost is approx $26.00 this mod will give you lower temps.

Cheers Altstart

I have used this unit to control my ferment fridge with no problems for about 4 months.
Cheers Altstart

 

[delboy]

Ok
like all you lads i want to use one of these jobbies to but i am as frustrated as most of you all are and have been about modding one to suit our applications and make it more flexable for largering and fermenting and storage so i have go off my bum and sent a letter to silicon chip mag asking them for help using there wide range of techs and enthus in this field of electronics .
i am sure they will help or reply with some sort of positive feed back so lets wait and see.

if they come up with a stable true temp controller for this devise then i will invest and build it it is good to see some of the mods out there but as i have read some of them are a little hard to use when it comes to temp settings when using an external pot .

i will do some work on these my self in the near future and try and work out some more stable mods and easier to use selector but at this stage i will wait to here from the gurus at SC MAG

DELBOY :beerbang:

 

[Joel]

I've added this file before on another thread (don't remember which). It's and excellent read if you want to make your own thermostat or digital thermometer.

View attachment Electronic_Thermometers_for_Brewers.doc

I built mine with a LCD readout so I can read the 'set temp' (the temp I set the pot to) and the actual temp of the fermenter with the flick of a switch. My temps read in farenheit. I still have some changes I want to make to the circuit, but thats all part of this homebrewing obsession of mine!

 

[agro]

agro,
when you wire a fixed resistor in parallel with a pot, the action will no longer be linear. I think its hyperbolic or something from memory. You'll need to buy a 500 ohm pot if your to keep it linear.

Pretty much what I was thinking. Ihave also tried a 500 ohm pot and I'm not entirely happy with the accuracy - probably accurate enough for 90% of uses, I guess I'm just that kind of person

It's all good fun

Cheers
Agro.

 

[recharge]

Im no electronics wizz so this may sound like a dumb question but here goes.

Would there be any reason not to run a couple of wires from pins 2 and 4 of the ic to the outside of case (maybe to a couple of pins or an rca type plug) for checking voltage when setting temps?

If ok would a couple of strands of cat 5 be good enough?

I dont mind fiddling with the little trimpot but trial and error has got to go and setting by the voltage is pretty damn accurate.

Cheers
:beer:

 

[agro]

No reason at all. Just don't solder to the IC - solder to the socket.

Cheers
Jason.

 

[recharge]

Too late for that. I soldered IC in before i realised it had a socket.(it didnt mention a socket on instructions or if it did i missed it but it was pretty obvious what it was for when left over not so for the extra resistor)
All works fine tho.
Dont think ill mess with this one as it will end up on chest freezer as a serving fridge so will put socket and additional rca plug into next one.

Cheers
:beer:

 

[agro]

Should be OK if your careful. The comparitor is easily damaged by heat which is why they provide the socket.

Jason.

 

[recharge]

Cheers for reply Jason. Will add socket to next one anyway.
And to think i was more concerned about damaging the sensor as i used a lighter to heatshrink tubing, hairdryer just wasnt doing it.

:beer:
Richard

 

[mazdacs]

Pretty much what I was thinking. Ihave also tried a 500 ohm pot and I'm not entirely happy with the accuracy - probably accurate enough for 90% of uses, I guess I'm just that kind of person

It's all good fun

Cheers
Agro.

Hi Recharge, Can you tell me how to locate pin 2 and pin 4 as I am having trouble with mine and I want to set the temp by voltage ?

chooks