A magnetic pickup generates its own signal. As the teeth of a gear or a toothed wheel pass the sensor face, they disturb the field of an internal permanent magnet and induce a voltage pulse in the coil behind it — one pulse per tooth, giving a direct measurement of speed.
Variable reluctance sensing
The sensor contains a permanent magnet with a coil wound around a pole piece. A ferrous tooth approaching the face concentrates the magnetic flux; as it moves away the flux falls. That changing flux induces a voltage in the coil according to Faraday's law — no external excitation needed for the sensing element itself.
Signal amplitude rises with speed and falls as the gap widens, so both matter. Set the air gap as small as mechanical clearance safely allows, and check that the signal is still readable at the lowest speed you need to measure.
Key features
- M18 threaded housing — standard size, straightforward to mount and adjust.
- Brass-plated construction — durable and robust in service.
- Corrosion resistant for long-term reliability in harsh conditions.
- 2 m cable as standard for flexible installation.
- Simple, rugged construction with no electronics at the sensing face.
Technical specifications
| Parameter | Value |
|---|---|
| Sensor type | Magnetic pickup (variable reluctance) |
| Housing material | Brass plated |
| Thread size | M18 |
| Supply voltage | 25 V DC |
| Cable length | 2 m |
| Frequency | 50 Hz |
| Corrosion resistance | Yes |
| Power source | Electric (DC) |
| Target | Ferrous gear teeth or toothed wheel |
Typical applications
- Speed sensing on rotating machinery, gearboxes and turbines.
- Position detection on conveyors and motor shafts.
- Industrial automation — feeding pulse counts to PLC high-speed inputs.
- Tachometer and overspeed protection systems.
How to order
Tell us the sensing gap, the target material, your supply voltage and the output type your controller needs. If you are replacing an existing sensor, a photograph of the body markings is usually enough for us to identify an equivalent. We will confirm the specification and quote — normally the same day.
Related products
Frequently asked questions
What air gap should I set?
As small as you safely can — typically well under a millimetre, allowing for shaft runout, thermal growth and any end float. A wider gap weakens the signal, and the effect is most noticeable at low speed where output is already smallest.
Will it work at very low RPM?
Output voltage is proportional to the rate of flux change, so at very low speed the signal becomes weak and eventually unreadable. If you need reliable measurement near zero speed, a Hall-effect sensor is the better choice because its output does not depend on speed.
Does it need a power supply?
The variable-reluctance sensing element generates its own signal. The 25 V DC rating covers the associated conditioning circuit; tell us your readout or PLC input type and we will confirm exactly what is needed.
Need a quote for the Magnetic Pickup Sensor (M18)?
Send us your application — target material, sensing distance, supply voltage and housing constraint. We will recommend a part, quote it, and ship from Mumbai.