Cooler Fan Circuit Design (electronics People Wtd)

[MearCat]

After reading up a fair bit on intercooler sprays and fans, I want to make a circuit that does something similar to what's described in this Autospeed article http://www.autospeed.com/cms/A_2478/article.html . In this article, the fan is turned on when a certain air flow (voltage) is reached, but I think this functionality would be completely complimented with some logic that turns the fan on when this voltage is reached AND when the difference between the ambient temp and intercooler temp reaches a certain amount. There is no point in having the fan on when the intercooler is not warmed up! Even if you are sitting stationary in traffic.

The hysteresis of the circuit will be determined by the AFM voltage and differential temperature and doesn't really have be configurable.

Eg. - The fan is turned on (via a relay) when the intercooler core is ~10 degrees above ambient AND air flow voltage is less than 1 Volt (say this was the AFM voltage at idle). When either the voltage goes above 1 Volt OR intercooler temperature drops below the 10 degrees difference then the fan is turned off.

It will involve 3 inputs - the AFM voltage and 2 thermistors.

Can ayone help is designing a circuit like this? I am competent in building electronics kits/projects but designing is a little beyond me. I think a circuit like this would be great for anyone with an intercooler that wants to prevent heat soak (especially prevalent to those WRX owners with top mount coolers)

-MearCat

[Scribble]

Sounds like an interesting project. Im no certified engineer, but i might have a stab at it when i get some time. Even just a basic design for someone else to have a look at and throw ideas at.

[GTRsean]

jaycar kits are good for that.

they have one for that application.

[MearCat]

jaycar kits are good for that.

they have one for that application.

<{POST_SNAPBACK}>

Yes - they have some good kits. But what I actually want is a merge of Jaycar Kit KC5381 ( Economy Adjustable Temperature Switch ) and KC5377 (UNIVERSAL VOLTAGE SWITCH )

I'm actually thinking of using a PICAXE microcontroller and some DS18B20 digital temperature senders to make it a lot easier than trying to design an analog circuit.

[PHATR32]

wouldnt it be easier to have a temp switch on or in the cooler it self which turns the fan on when it his a certain temp?

[MearCat]

The whole idea of it was to make to more intelligent that just switching on a fan at a certain temp (as explained in the first post). Only wanting to turn it on when needed - reread the first post

Edited September 29, 2005 by MearCat