Re: RE: Deep electronic question..

From: Don (y2kota@y2kota.us)
Date: Sun Jun 20 2004 - 23:11:08 EDT


I've heard about the micro switch and flat piece of of something
before. I was hoping for a voltage from some where to throw a relay.
The idea of the use the VSS is what I might start looking at. I have a
toggle switch now that I use, but it sucks when I forget to turn it
back on.

Don

On Sunday, June 20, 2004, at 03:40 PM, jon@dakota-truck.net wrote:

>
> Don <y2kota@y2kota.us> wrote:
>
> : I trying to find a way to turn off the ele. fan at speeds above 40mph
> : and turn on when below 40mph.
>
>
> I have heard of people accomplishing this in the past by hanging
> "something" in the airstream - where exactly, depends on the particular
> vehicle - perhaps next to the radiator, perhaps somewhere in the air
> dam area, etc. Anyway, the "something" is basically a flat piece of
> metal, plastic, etc. whatever you might happen to have handy. You set
> it up such that as it is blown back, it triggers a microswitch (which
> is used as the input to a relay to interrupt the fan circuit). You
> just need to play with the size of the flap until you get it to the
> point where it is triggering the microswitch at 40mph. (Picture
> something, perhaps the size of a playing card, hanging under the
> truck, with a hinge at the top, and a microswitch positioned behind it
> such that it will trigger it when it is blown back far enough.) I
> don't recall now where I saw this, but as I recall, it was quite
> effective.
>
> It might also be possible to use something similar to a Hall type
> air speed indicator (popular on ultralights due to their light weight
> and low cost) Basically, its a vertical tube, with a ball in it,
> and at the bottom, a pitot tube facing into the wind. As you go
> faster, the air pressure pushes up on the ball, and raises it in the
> tube. The tube then has marks on the side showing what speed
> you are at when the ball is at that point. (An actual air speed
> indicator would normally use a flat disk which rides on a pin,
> but if you are going the DIY route, a ball would probably be
> simpler.) In your case, you wouldn't need the graduations, just
> a microswitch at the level which corresponds to 40mph.
>
> The slickest solution would be the one already offered by other
> DMLers - use electronics to count the pulses from the VSS or an ABS
> sensor. However, if you aren't handy with electronics, one of the
> above methods might be a way to get it done.
>
> --
> -Jon-
>
> .-- Jon Steiger ---- jon@dakota-truck.net or jon@jonsteiger.com --.
> | 1970 Barracuda - 1990 Dakota 'vert - 1992 Ram 4x4 - 1996 Dakota |
> | 1996 Intruder 1400 - 1996 Kolb FireFly - 2001 Ram QC 3500 CTD |
> `------------------------------------ http://www.jonsteiger.com --'
>
>



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