AI-Tek 70085-1010-056 Passive Magnetic Speed Sensor | Variable Reluctance Pickup
Engineering Background
AI-Tek Instruments (formerly Airpax) has been a benchmark manufacturer of variable reluctance (VR) speed sensors since the 1960s. The 70085-1010-056 belongs to the 70085 series — a field-proven passive magnetic pickup family widely deployed across industrial drives, turbines, and precision motion control systems. No external power supply is required; the sensor generates its own sinusoidal output signal through electromagnetic induction as ferrous gear teeth pass the sensing tip.
Product Positioning
Designed for procurement engineers and OEM integrators who require a drop-in, specification-matched replacement or new-build component. The 70085-1010-056 delivers reliable frequency output proportional to rotational speed, making it the preferred choice for tachometer feedback loops, overspeed protection circuits, and closed-loop drive control in demanding industrial environments.
Complete Technical Specifications
- Part Number: 70085-1010-056
- Manufacturer: AI-Tek Instruments (Airpax)
- Series: 70085 Variable Reluctance Speed Sensor
- Sensor Type: Passive Magnetic Pickup (Variable Reluctance)
- Output Signal: Sinusoidal AC voltage, amplitude proportional to speed
- Operating Principle: Electromagnetic induction — no external power required
- Coil Resistance: Refer to OEM datasheet (typically 150–3000 Ω range for 70085 series)
- Target Material: Ferrous gear/toothed wheel
- Thread Size: Refer to OEM datasheet (standard 70085 series: 3/4-16 UNF or M18×1.5)
- Housing Material: Stainless steel / nickel-plated brass (series standard)
- Connector: Integral cable or Packard/Deutsch connector (verify per suffix -056)
- Operating Temperature: -40°C to +150°C (series standard)
- Weight: 650 g (packaged)
- Country of Origin: USA
Proven Application Environments
- Industrial variable frequency drives (VFD) — speed feedback
- Gas and steam turbine overspeed protection systems
- Diesel engine tachometry and governor control
- Conveyor and rolling mill drive monitoring
- Marine propulsion shaft speed measurement
- Wind turbine gearbox RPM sensing
- CNC machine tool spindle feedback
- Compressor and pump protection panels
Engineering Advantages
- Self-powered: No auxiliary supply needed — simplifies wiring and eliminates power-supply failure modes
- Robust sinusoidal output: Compatible with virtually all industrial speed controllers and PLCs with frequency input cards
- Wide temperature range: Suitable for both ambient-temperature panels and high-heat engine compartments
- Stainless steel housing: Corrosion-resistant for washdown, outdoor, and chemically aggressive environments
- Direct OEM replacement: Suffix -056 ensures dimensional and electrical compatibility with original installation
- Long service life: No moving parts, no electronics — MTBF exceeds 100,000 hours in typical installations
System Architecture & Signal Flow
The 70085-1010-056 operates on the variable reluctance principle: a permanent magnet within the sensor body creates a static magnetic field at the sensing tip. As ferrous gear teeth pass through this field, the reluctance of the magnetic circuit changes cyclically, inducing a sinusoidal voltage in the coil. Signal frequency (Hz) is directly proportional to shaft RPM and the number of gear teeth:
f (Hz) = (RPM × Teeth) / 60
The output feeds directly into a speed controller’s frequency input, a dedicated tachometer card, or a PLC analog/frequency module. Signal conditioning (Schmitt trigger, zero-crossing detector) may be applied downstream for long cable runs or low-speed applications.
Sourcing & Quality Verification
- All units sourced from authorized distributors or verified OEM surplus channels
- Each unit inspected for coil continuity, housing integrity, and connector condition prior to dispatch
- Original manufacturer packaging preserved where available
- Traceability documentation available upon request (lot number, date code)
- Counterfeit-risk assessment performed — AI-Tek 70085 series is a known target for grey-market substitution; Konmask.com applies strict incoming inspection protocols
Procurement Process
- Confirm part number suffix (-056) matches your existing installation or OEM BOM
- Verify thread size and cable length against your mounting bracket specification
- Add to cart and complete checkout — HKD pricing, international shipping available
- For bulk orders (>5 units) or project quotations, contact support@konmask.com
- Lead time: in-stock units ship within 1–3 business days; ETA confirmed at order
Technical FAQ
Q: Does the 70085-1010-056 require an external power supply?
A: No. It is a passive sensor — it generates its own output voltage through electromagnetic induction. No 24 VDC or other supply is needed at the sensor.
Q: What is the minimum detectable speed?
A: Minimum speed depends on gear tooth count and the input threshold of the receiving device. Typically >30 RPM with a 60-tooth gear produces a reliable signal. For very low speeds, consider an active Hall-effect sensor instead.
Q: Can I use this sensor with a PLC frequency input card?
A: Yes, provided the PLC input card accepts sinusoidal or zero-crossing AC signals. Verify input impedance (>10 kΩ recommended) and voltage threshold compatibility with your specific PLC module.
Q: What is the difference between the -056 suffix and other 70085 variants?
A: The suffix designates specific dimensional, cable, and connector configurations. The -056 variant has a defined cable length and connector type per AI-Tek’s internal part numbering. Always match the full part number to your OEM specification.
Q: Is a certificate of conformance (CoC) available?
A: Yes, upon request for orders of 2+ units. Contact support@konmask.com with your order number.
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