Thermostat/Thermistor Question - SOF Chiller

[discooby]

I keep bumping this cause I wanted to know. And now I do... maybe someone else will too.

I just built a chamber using the 6020 ritetemp and it works great. I’m using battery power, left the default jumpers in place (reply if you want to know what they are cause I cant remember with all the hm cider right now), and wired it:

Power-wall-wort (hot) to G on Rite Temp, RH to hot fan, ground from fan back to 12 vdc wall-wort. And it works great! Don’t forget about the two minute delay between turning the fan on when changing temps on the thermostat.

Also, don’t forget to take out the temp controller and rewire that sucker to a longer cord. But it’s in the instructions… while they last. Also, good luck finding a 6020, I think that may burry this one… but then again, I assume all thermostats use the same crazy G, RH, etc.???

 

[Ppeg34]

These things are actually on Amazon for $16!

I am gonna go ahead and order it, but I think I am a little confused about what all I need.

Do I just need the thermostat and a wire lead or do I need a relay and other confusing things?

This seemed like it would be pretty straightforward until I read this post.

 

[discooby]

If you are using it for a SOF then you need a thermostat (RiteTemp 6020), a 12VDC computer fan, a 120V AC to 12V DC wall plug, some spare electrical wire (24 or-so gauge), some shrink tubing (you can find that at O’Reilly, Checker, or any auto parts store – cheaper than Radio Shack- You will need a hot air source like a hot blow dryer to shrink the tubing), a pencil-point solder gun (like $10 at RS or wallyworld), and some solder wire (I used .032 dia.). -I tried posting links to the shrink tubing, solder gun, and wire solder but right now HBT only likes Amazon links!!!!

If you are using it for something else (to control a freezer) then you might need to look at other posts/threads.

There is no need for a relay or any other confusing things. For the 120V AC to 12V DC wall plug you could use a cell phone charger or better yet, if you have an old Linksys router use the wall plug for that… those are 12V DC. Some cell phone chargers pump out only around 6-9 V DC which will work but make the fan run slower. Use the same size wire of the power supply (or pc fan) as a guide for the rest of your wires.

Follow the instructions that are online or see my post above. As far as the OP’s problem, I suspect the wiring was wrong or it was a bad thermostat. As I posted above, it was super easy to do (I even soldered it with little to no experience). Use youtube for instructions on how to solder if you’re new at it.

Hope this helps! Let me know if you have any more questions

 

[TSB]

One thing to check is the output voltage on your power supply when it is not connected to anything, and then put a known load on it (say a 2K, 1/ watt resistor). Place the load across the output wires or terminals, and measure the voltage again. If it is not 12 V in either case you have what is called an "unregulated power supply." These are the most common kind, and each is designed for a specific load. If this is the case, you must fix it before we can do anything with your other readings, because voltage is not being held constant, so the addition of the thermostat and then the thermistor will change the voltage present, and hence the readings you are obtaining.

A simple fix for under a $2.00 is (first check that your open circuit voltage is about 14.5 VDC) to put a 1000uF/25V capacitor across the power leads, then connect the positive and ground leads to a 7812 power controller in a TO-220 case, then put a 10uF/25V capacitor (possibly tatalum) across the outputs (positive and ground) or the voltage regulator. Connect the grounds all at one position, by the way. Protect the regulator by placing an inexpensive silicon signal diode (e.g., 1N914, 1N4148, etc.) from the chip output to the chip input (pointing backwards, or so it seems when you draw it). Now you have 12 V to about +-3% regardless of the current in the system as you attach other components. If you are going to draw more than about 50 mA, use a heat sink on the TO-220 package (which will then allow up to 500 mA, much more than you would need). Some lower-cost sources for the partsare noted below.

Regards,
Tom Bellows
TSB Engineering Co.

www.bgmicro.com
www.allelectronics.com
www.mpja.com