Home made electronic fan controller.

[mikyrc]

I installed an oil radiator with an electric fan and I didn't want to to hook it to the regular coolant fan to control it because both temps aren't the same.
So I designed an electronic fan controller for my oil radiator fan.

If anybody is interested in the schematics, just ask.
The only thing You need is an aftermarket oil temp gauge, so the circuit can know at what temp turn the fan on and off.

[Kapok6]

I installed an oil radiator with an electric fan and I didn't want to to hook it to the regular coolant fan to control it because both temps aren't the same.
So I designed an electronic fan controller for my oil radiator fan.

If anybody is interested in the schematics, just ask.
The only thing You need is an aftermarket oil temp gauge, so the circuit can know at what temp turn the fan on and off.

If you could post the schematics up for the forum to see that would be very beneficial to the community.

[mikyrc]

Ok, once I arrive at home I'll post it here.

[hakcenter]

using a op-amp to drive it ?

[mikyrc]

An op-amp as a comparator, a pair of transistors a relay and some other small stuff like resistors, potentiometers to set the temp, diodes and such.

[hakcenter]

very cool

[mikyrc]

Here it goes:




Any questions just ask.

[hakcenter]

obviously much more complicated than something I could create   

Really good job there sir, you ought to consider having a couple of boards made if you haven't already.

[mikyrc]

Thanks Hak, but it's not that complicated once You understand how it works.

It's just a doble comparator, one for the "FAN ON" temp and the other one for the "FAN OFF" temp.
But the circuit must "remember" it's last state when between the ON and OFF temps, and that was the hardest thing to design.
But I finally got it using a double circuit relay with NC and NO contacts.
Also had to add a pair of transistors to be able to drive the relay as the comparator itself doesn't provide enough current.

The 1Mohm resistor on the comparator is to create some hysteressis (smitt trigger) to avoid bouncing on the relay (that happens when the temp is so close to the switch point that the comparator switches back and forth).

About the boards, I haven't done anything, just the prototype.

[Kapok6]

Thought about making these to sell?  This stuff is WAY over my head to make myself.

[mikyrc]

The truth is It wouldn't be easy for me to do it without taking me a lot of time and effort. And just to sell 5 or 10 controllers.
I should find somebody that would make the printed circuit boards cheap and that doesn't require 500 units minimum or whatever.

[hakcenter]

The truth is It wouldn't be easy for me to do it without taking me a lot of time and effort. And just to sell 5 or 10 controllers.
I should find somebody that would make the printed circuit boards cheap and that doesn't require 500 units minimum or whatever.

BatchPCB, $2.50 a square inch for double sided. Great for prototyping.

If it becomes a hot item, you can get a platter from a place I know, 100square inches for $100.

[Kapok6]

I would definitely be interested in something like this.  I have an external ATF cooler and intend on running and aftermarket external oil cooler as will and if I could put fans on both that would be great.

Just a thought.

[citymunky]

Thought about making these to sell?  This stuff is WAY over my head to make myself.

+1, it would be cool to control the temp my fan for my rad. 

[John_H]

holy crap, the talent is coming out of the woodwork!!

Good job man!

Could you make it a 2spd/3spd operation?

some sort of resistor or even pulsewidth modulated?