My ‘Water to Air’ heat exchanger has twin Spal fans mounted to it for slow moving traffic. Using a hot wire sensor I measured the fans move the air at a speed of 19kmph, so an Arduino controller will switch off the fans at 20kmph when accelerating and switch back on below 20kmph.
I setup an oscilloscope in the car connected to the Speedometer input to measure the frequency at set speeds. Unfortunately at speeds below 30kmph it reads 30Hz which does not sit well with an Arduino (doesn’t like anything below 30Hz).
So all I could figure was to make my own tooth wheel and mount it on the diff flange. Then use a sensor to supply a much higher frequency at low speed.
I had the wheel water jet cut out from steel and then tac welded the two halves together so I could machine it. Once machined i just folded it in half to break the tac welds like a biscuit.
I mocked up the VSS bracket from MDF before sending the file off to be laser cut from stainless steal. Once folded into position it was then fusion welded together. (Will have everything plated black)
