Hey everyone! This is my first post on the site and I need some help wiring a project.

I have a 2 wire 12v dc fan I want to control using two separate 12v dc fan controllers and a thermostat. I want the fan to always run at a lower speed set by one fan controller and if the thermostat reaches the set temperature then it will switch to the higher speed set by the other fan controller. Is there anything else I need or how should I wire them up? Thanks!

 

Only how to feed the fans either by Mosfet pwm or relay....Ideally if you have any information on the temperature controllers...

 

Realized I probably posted this question in the wrong section. Anyways it's a w1209 temperature control switch. I have a spdt relay I could use as well? Sorry I'm new to electronics projects.

 

Is there anything else I need !

I don't know about you, but what I need is information on the fan, information on the fan controllers, information on the power source, and information about what fan speeds you want to hold. Information such as pdf's or direct links.

For example, if you want a 12 V, 1 A fan to switch between 50% and 100% speed, then you *might* need nothing more than the thermostat, 1 resistor, and no "controllers".

ak

 

Fan: https://www.rpelectronics.com/cfa1212038mb-12vdc-ball-bearing-120mm-fan.html
Fan controllers: http://s.aliexpress.com/aqM3EbYb

I'd like the fan to be variable speed that's why I don't want to use just a resistor and I already have these parts. Im using a 12v 20a power supply. Most of the time I would want the fan at 45% and then switch to 75% if the w1209 thermostat races is set temp. Thanks for the help.

 

You're going to need a Speed controller similar to this...

https://m.ebay.co.uk/itm/3V-35V-12V...944706?hash=item2a5719f282:g:QwsAAOSw0JpV4L3y

Then your temperature module can override the slow speed with the relay output and a seperate speed pot.

 

Would this work? I would like something with a display.
http://s.aliexpress.com/ZvyUbMBR

 

Yes same thing, set the speed, and use your temperature module to control the boost override.

 

So how should I wire them? I was going to wire 12v in to the thermostat and a spdt relay, then the thermostat output to the relay coil, another 12v line running through the relay and each relay output would go into a separate speed controller. The outputs of the speed controllers would then both connect to the positive and negative wire on the fan. Is this correct? Can current flow back into the non energized fan controller if I have both positive wires and both negative wires connected?

 

Probably the best way is to have a controller that can output deviation or MV-SP (Measured value - Setpoint) or has a DEVIATION ALARM. The high speed is used when the deviation is greater than some value.

 

So how should I wire them? I was going to wire 12v in to the thermostat and a spdt relay, then the thermostat output to the relay coil, another 12v line running through the relay and each relay output would go into a separate speed controller. The outputs of the speed controllers would then both connect to the positive and negative wire on the fan. Is this correct? Can current flow back into the non energized fan controller if I have both positive wires and both negative wires connected?

Only one speed control is needed, use the thermostat pcb to switch in a separate potentiometer to set the fast speed, then when that kicks out back to low temperature, relay puts the original potentiometer back in circuit for slow speed.