Power Instruments 1891-M Digital Phototach Operating Directions

The Power Instruments 1891-M Digital Phototach is a portable, battery-powered optical tachometer designed to measure the rotational speed of shafts, fans, motors, or any reflective surface without physical contact. It uses a light beam and reflective target method to determine revolutions per minute (RPM) with high accuracy and reliability. Model: 1891-M Type: Digital “Phototach” Non-Contact Tachometer Function: Measures rotational speed (RPM) via reflected light beam Measurement Range: 10 to 100,000 RPM (depending on reflectivity and marking method) Accuracy: ±0.5% of reading ±1 digit Display Type: Digital 4-digit LED display (RPM indication) Measurement Distance: ⅛ in to 25 in (3 mm to 635 mm) from reflective target Sensing Method: Photoelectric optical sensing using light reflection Target Marking: Uses reflective tape (Scotchlite) or half-black adhesive label for contrast Memory Function: Stores last recorded reading for recall Power Source: 1 × 1.5 V “D” cell battery and 1 × 5.4 V TR134-R battery Battery Life: Approx. 40 hours continuous operation Probe Lamp: G.E. 222X miniature incandescent bulb (replaceable) Maintenance Access: Bottom-mounted screws for battery compartment and probe lamp replacement Housing Material: Powder-coated aluminum enclosure Operating Temperature: 0°C to +50°C Storage Temperature: -20°C to +60°C Dimensions: Approx. 200 mm × 110 mm × 70 mm (7.9 in × 4.3 in × 2.8 in) Weight: Approx. 800 g (1.75 lb) with batteries installed Indicators: “Target Eye” LED illuminates when beam contacts reflective surface Included Accessories: Reflective tape, operating instructions, and carrying case Application: Motor speed verification, fan RPM testing, machine rotation diagnostics, and vibration system calibration Manufacturer: Power Instruments, Inc. Address: 7352 N. Lawndale Avenue, Skokie, Illinois 60076 Country of Manufacture: USA Please review pictures carefully and let us know if you have any questions!