Speed dependent switch operation

I want to make a cicuit with following features:
Speed of a car is sensed by a axle generator( it is not a part of my ckt) which generates speed dependent frequeny or voltage. It is to be rectified and fed to my ckt. this ckt has to operate three switches or relays at three pre desired speeds e.g. at 15 kmph relay 1 will operate, at 30 kmph 2nd relay and at 45 kmph third relay will operate,
please send me details of components and ckt diag,
thanx alok

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please send me details of components and ckt diag,
thanx alok[/quote]

You don't ask for much do you? :wink:

I'll give you some ideas but leave the ckt diagram and components for you to work out

Feed the output from your drive shaft sensor to a 2907 tacho chip. This converts the pulses to a voltage. Feed this voltage to a 3914 chip and use the appropriate LED outputs to drive your relays (via a transistor). You may have to experiment a little to fine tune the exact speed/ relay operation.

Good luck,

Klaus