Air Pressure Relay Trigger

All,

I was on the Auto Speed website (Australia) the other day and they had a series of articles on using an airpressure sensing device to control a whole host of things (air cleaner indicator, intake water injection controller, speed triggered controller.) What I had in mind was a device to shut down the electric fans once the car achieves around 45mph.

Unfortunately, the pressure sensing device is no longer available through Auto Speed. I contacted the manufacturer, but they mainly sell to OEMers. In order to do a direct purchase, I would have to buy 20 of these sensors at around $15/each. The remainder of the circuitry is fairly simple and could probably be purchased at Radio Shack for less than $20 or through Auto Speed for around $5 plus $8 shipping. (This circuitry provides an anti flutter shut off delay and a transistor controlled step up relay so that an automotive rated relay can be triggered.)

Click here to see the article Auto Speed Pressure Switch

The question is would enough people be interested in this to warrant purchasing the minimum quantity of sensors??

I just got an email from one of the editors from Auto Speed telling me that they had found a supplier for what he said was a better pressure switch than the one they had previously offered. The cost was quoted at around $8 USD. That would make the cost of the parts to build this controller at around $13.00 USD. Not bad for a controller that will sense the speed of the car with what is in essence a pitot tube and deactivate the fans at selectable speed.