ebay aquarium temp controller build - Page 14

sharpstick · 04-14-2010, 11:41 AM

Quote:

Originally Posted by Weissbier

I tried to wire mine up with an Auberins thermocouple and it didnt work. This model to be specific, http://www.auberins.com/index.php?main_page=product_info&cPath=3&products_ id=109 I would be interested to know if the controller would work with another probe as well. I had little luck searching for Replacement NTC Probes, this was about all I could find...

i've tried switching probes on digital oven thermometers and they weren't calibrated the same. so unless the specs match, it's a crapshoot.

**ubermick** · 04-14-2010, 07:30 PM

Okay, so I'm getting ready to wire this up. It's all really self explanatory, but I've got a question about adding a fan to the mix. Basically I want to include a fan in the fermentation chamber that fires whenever the heat or the cool is active. Here's my basic wiring (the blue and red circles represent lights that'll pop on whenever the controller is heating or cooling.. what can I say, I'm a sucker for more lights!)

The orange wires output from the heat/cool output terminals on the controller, are joined together by a wire nut, and then off to the 110v fan. But the more I think about it, the more I question whether this will work: because I'm thinking that, let's say the hot side fires, it'll provide juice to ALL the fan wiring, which will in turn provide power to the cooling side?

wyzazz · 04-14-2010, 07:44 PM

Quote:

Originally Posted by ubermick

Okay, so I'm getting ready to wire this up. It's all really self explanatory, but I've got a question about adding a fan to the mix. Basically I want to include a fan in the fermentation chamber that fires whenever the heat or the cool is active. Here's my basic wiring (the blue and red circles represent lights that'll pop on whenever the controller is heating or cooling.. what can I say, I'm a sucker for more lights!)

The orange wires output from the heat/cool output terminals on the controller, are joined together by a wire nut, and then off to the 110v fan. But the more I think about it, the more I question whether this will work: because I'm thinking that, let's say the hot side fires, it'll provide juice to ALL the fan wiring, which will in turn provide power to the cooling side?

Methinks you'll need a diode inline on each hot leg.

sharpstick · 04-14-2010, 07:53 PM

Quote:

Originally Posted by wyzazz

Methinks you'll need a diode inline on each hot leg.

that will work if the entire system is DC, but aren't the heating and cooling outputs AC?
the easiest way is to put separate fans on each circuit. or a switch to transfer the fans power line from one or the other. you won't typically be using both heat and cold at the same time anyway, right?

**ubermick** · 04-14-2010, 08:00 PM

Quote:

Originally Posted by sharpstick

that will work if the entire system is DC, but aren't the heating and cooling outputs AC?
the easiest way is to put separate fans on each circuit. or a switch to transfer the fans power line from one or the other. you won't typically be using both heat and cold at the same time anyway, right?

Yup, it is indeed all AC. I'd really rather avoid having separate fans in there, but wouldn't a switch mean the fan would be running 24/7 while the unit is on?

sharpstick · 04-14-2010, 08:16 PM

Quote:

Originally Posted by ubermick

Yup, it is indeed all AC. I'd really rather avoid having separate fans in there, but wouldn't a switch mean the fan would be running 24/7 while the unit is on?

no, i meant a double throw switch that supplies the power to the fan from either the heating or the cooling output. the fan will run only when it's respective circuit is energized.

**ubermick** · 04-14-2010, 08:23 PM

Quote:

Originally Posted by sharpstick

no, i meant a double throw switch that supplies the power to the fan from either the heating or the cooling output. the fan will run only when it's respective circuit is energized.

Gotcha. I'd still have to manually flip that switch any time the conditions changed from cooling to heating tho, right? (For example in the summer, cools during the day, heats at night?)

shushikiary · 04-14-2010, 08:32 PM

I dont think a diode would fix the problem. It's AC, so you'd only cut out 1/2 of the voltage wave.

If you wired it that way, when the fan turned on the current would run back up the other line and try to power both your heating and cooling element from one 10a output from the controler.

You need to have a switch that will turn off the connection to the opposite output when the other is on.... lol what you need is an AC OR gate, but as far as I know they dont make one.... hmm... I dont think you want to do AC-DC to use an OR gate to control a 3 way relay... so let me think if I can come up with something else...

I've got it... a normally closed relay would solve the problem for you:

http://www.onlinecomponents.com/buy/AMERICAN-ZETTLER/AZ2280-1C-120A/

You wire the power from one of either your cool or heater to the coil, then wire the one you wired to the coil to the closed contact when the relay is powered, then wire the other one to the closed contact when the relay is off... then wire the fan to the common contact.

I.E.

Given the above, you would wire say the heater switch hot output (pin 6 in your diagram) to 1 and 3, then wire the cooler switch hot (pint 8 in your diagram) output to 2, wire 5 to neutral, and 4 to the fan's hot input, and of course the fans neutral to neutral.

You'll have to use a volt meter to figure out which terminal is normally closed (the one connected to 4 when no current through the coil) and which one is normally open (the one connected to 4 when current is through the coil), and wire appropriately, unless they are labeled.

make sense?

wyzazz · 04-14-2010, 10:46 PM

If I'm not mistaken you can use a diode with AC voltage with a resistor wired in series like explained here.

shushikiary · 04-15-2010, 03:28 AM

Quote:

Originally Posted by wyzazz

If I'm not mistaken you can use a diode with AC voltage with a resistor wired in series like explained here.

The issue is that even with the resistor the negative half of the sin wave will pass through the circuit to the heater/cooler which ever one isnt on. Dependant on how they are built that could turn them on, or damage them. Most likely on the heater you'll end up running it at 1/2 power, minus what the resistor pulls out.

On the cooler side, if it has any DC powered elements in it, and the power supply was not designed robustly and is using a full wave rectifier then you can cause a "brown out" condition in which you can destroy the electronics in the fridge, else you can cause the compressor to waste power by not getting it to spin and possibly over heat coils, OR depenent on how the compressor is designed, you may run it at 1/2 its normal rotational speed.

next, putting the diode there would cut the other half the sin wave off to the fan, either making it not run, or making it run at 1/2 speed, depenant on how they designed the motor.

even so, in this case a resistor isnt needed because the diode is in series with the load, either the heater or cooler, which already have their own "resistance" (reactance), and you wouldnt burn the diode out due to over current as long as it was rated for 10 amps like the controller (and a greater than 169v reverse bias, as the 120 is RMS voltage so 120 * sqr root(2) = about 169)

it "could" work, but I wouldnt try it if I was you.... speaking as a EE.