Fan Tray Mod Question

wildest_jjk said:
So the power that is going to the thermostat will not power the fans? It will need an external power source?

Sounds pretty cool, would you be using something like the circuit you posted above?

Not to worry if you cannot find the probe, don't want to cause you any extra hassle :)

Thanks for all the help.
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1. No it won't. Your fans will need their own power source. It's convenient though as you'll just plug it in to a mains outlet. The connecting pins are recessed inside the body of the device so there's no danger unless you go shoving metal things in there.

2. Maybe, I haven't proven the design yet and investigated what sort of real world loads it can take. I did look into a 555 based design for the temperature based element and it can be done easily but I think I would need matching opposing pairs of thermistors. Not a huge issue but I was hoping to make this without needing to buy any additional parts and just make it all from stuff I've salvaged or already have to hand. I can also use a 555 and a Opamp to get the same result with just a single thermistor but would need some work on the balancing.

I'm looking at making a fan controller that uses about 3 or 4 methods to control all manner of fans from automated PWM control to manual dial DC control. I may integrate an Arduino or at least a microcontroller to give me tach feedback on a 7 segment LED display (salvaged from these very devices). It'd be nice if I could use Nixie tubes but I'm not sure if I want to go there just yet. I might make a project log out of it eventually. :)

3. I may have cut the probe I have in the garage off one of these devices I stripped for parts so it may be the right one.
 
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Gave the temperature controller a quick test and it powers up, shows the correct temperature, switches on the relay and my fans start. Sadly I can't change any of the settings at the moment. I'm following the manual and nothing works as it should. Maybe this is defective and likely why it was under the bench in the office. Will try the other later.

If I were you I'd order your own as originally planned. I'm not hopeful of these things.
 
Ok no problem but thanks for all the help and spending your time looking at it :)

I think you have answered this question already but I am still unsure about how the power works. In terms of the thermostats I was talking about do I need a 12V or a 240V? I am guessing the 12V as this is the same as what will be outputting to the fans?

How do I power the thermostat and the fans? Seperate power supplies?

Thanks for your patience :)
 
1. It's up to you. 12v may be easier if you already have a 12v power supply for the fans and you won't kill yourself wiring it up like you could when fiddling with mains stuff.

2. One would do it. The temperature controllers aren't that heavy with power although the relay does use some power it won't be that much. Maybe a 12v 2A if you are only using 2 or 3 fans, more like 5A if you want more.

You just feed the 12v into the controller in paralled with the fan load. Break the power lead to the fans and feed either side of the break to the relay. So when the relay is switched on the wire becomes whole again and the electrons can flow.

Thinking about this electronically though the circuit you need is quite different to that which I detailed above. What you are looking to use can be done with a comparatpr set up as a schmitt trigger, a few passives and maybe a MOSFET. A schmitt trigger allows hysteresis as it will turn on and off at preset thresholds.
 
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Tealc said:
1. It's up to you. 12v may be easier if you already have a 12v power supply for the fans and you won't kill yourself wiring it up like you could when fiddling with mains stuff.

2. One would do it. The temperature controllers aren't that heavy with power although the relay does use some power it won't be that much. Maybe a 12v 2A if you are only using 2 or 3 fans, more like 5A if you want more.

You just feed the 12v into the controller in paralled with the fan load. Break the power lead to the fans and feed either side of the break to the relay. So when the relay is switched on the wire becomes whole again and the electrons can flow.

Thinking about this electronically though the circuit you need is quite different to that which I detailed above. What you are looking to use can be done with a simple schmitt trigger, a few passives and maybe a MOSFET.
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Can I get away without buying a 12V supply then? It's just I don't actually have one at all yet.

Thanks
 
Ok so I have got a Bitfenix Recon off of the forums. I know the max amperage for the fans I am going to get but how do I know what the controller needs?

I have a 12V 2A adapter but I'm not sure if that's enough.

Thanks :)
 
The recon doesn't use much. The screen uses two LEDs for illumination, it has a couple of ICs and some EEPROM on board and uses a similar circuit to my PWM converters so is quite efficient. Maybe 2 or 3 watts tops I reckon plus whatever your fans draw at a given speed.
 
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