LM2907 and LM2917 devices operate when the input frequency reaches or exceeds a selected ratio. are monolithic frequency-to-voltage converters with a high-gain op amp designed to drive a relay, lamp, or other load.
The op amp is fully compatible with the tachometer and its output It has a floating transistor. This feature allows ground or supply source load up to 50 mA. The collector can be taken above VCC up to a maximum of 28 V VCE.