Speed Alarm Monitors Tach Pulses From Nine Fans

The SmartFan TachScan-9 digital fan speed alarm monitors tach pulses from up to nine dc or ac fans or blowers. The compact 5" x 1.5" alarm provides both individual and ORÕd pass/fail signals and is compatible with any fan that provides open collector or voltage source tach pulses. Three trigger speeds are user selectable via an on-board jumper. When fan speed falls below the set trigger speed, alarm signals are generated to drive LEDs, logic, optical isolators or MOS relays. The alarm accepts any supply voltage from 6 to 60 Vdc and distributes power to dc fans through the same header used to sense tach pulses. It can also be used to power the dc tach circuits built into ac fans and provides simultaneous NO and NC isolated outputs from a dual-pole MOS relay, which can sink up to 100 mA of current to drive heavy loads. For additional information and pricing, contact Jim Quirk at CONTROL RESOURCES, INC., Littleton, MA. (978) 486-4160.