The 14-pin DIL IC is extremely easy to use since Vltsubgt OUTltsubgt Fltsubgt I Nltsubgt x Vltsubgt C Cltsubgt x VR1 x C2 where VR1 is the resistance between pin 3 & ground & C2 is the capacitance in Farads between pin 2 & ground. Features include ground referenced tachometer whose input interfaces directly with magnetic variable reluctance pick-ups op-amp comparator with floating relays solenoids meters or LEDs etc frequency doubling with low ripple tachometer with built-in hysteresis for either differential or ground referenced input built-in zener for accurate & stable frequency to current conversion & linearity typically plusmn 0.3. Applications include overunder speed sensing tachometers speedometers breaker point dwell meters h&-held tachometers speed governors cruise control touch or sound switches etc.