G Series OHW OHWG Wiegand sensor General Description OHWG series wiegand sensor is new-type magnetic sensor based on wiegand effect. It can convert the magnetic signal into voltage output without additional power supply, so it is also called zero power magnetic sensor. Wiegand sensor is composed of magnetic bistable function alloy wire made by special processing and induction coil winded outside. When an alternating magnetic field of proper strength is applied to the Wiegand wire, the magnetic field of the core switches polarity and then reverses, causing the Wiegand pulse to be generated.Magnetic switching occurs when the wire is in the presence or alternating longitudinal magnetic fields. The pulse amplitude is not totally dependent on excitation field strength and orientation.The alternating positive and negative magnetic fields of equal saturating strength are used to magnetize and trigger the Wiegand wire. These alternating magnetic fields are typically produced by magnets which are affixed to the rotating or moving equipment, by a stationary read head and moving Wiegand wires, or by an alternating current. This remarkable technology offers new capabilities in proximity sensing, tachometry, rotary shaft encoding, speed sensing, and many other applications. Features · No additional power supply during operating time · When trigger magnetic induction intensity is 2mT, the output voltage amplitude could reach 1V. When 8mT, the output voltage amplitude could be higher than 4V · Amplitude of output signal has nothing to do with the change rate of magnetic field, achieving “zero speed” sensing · No touching point, enduring erode, water-proof, explosion-proof and having a lifespan of 2 billion times · Achieving electrical signal long-distance transfer by using telephone line and coaxial line,etc. Applications Wiegand sensors are used in water, gas, and electric meters for electronic indexing. They also havemany automotive applications such as antilock braking, speed sensing, and position indicators. They have been used in anemometers and other wind speed applications, machine controls, shaft speed sensing, and numerous rotational counting applications. Nanjing Ouzhuo Technology co., Ltd Tel：86-25-52312738，86-25-83247886 Page 1 www.ohhall.com FAX: 86-25-52312738 www.zbling.com E-mail: [email protected] G Series OHW OHWG Wiegand sensor Characteristics Trigger Magnetic Flux Density ( mT ) Min Best Value Max Output Voltage VO（V） OHWG112 2.5 7～8 12 ≥1.5 10～50 -20～+125 OHWG113 2.5 7～8 10 ≥2.0 10～50 -20～+105 OHWG113A 2.5 7～8 10 ≥2.0 10～50 -20～+105 OHWG115 2.5 7～8 12 ≥1.5 10～50 -20～+125 OHWG214 2.5 7～8 12 ≥1.5 10～50 -20～+125 OHWG311 2.5 7～8 12 ≥1.5 10～50 -20～+125 OHWG312 2.5 7～8 12 ≥1.5 10～50 -20～+125 Type Typical Pulse Width Valueτ （μS） Operating Temperature RangeT（℃） Structure and dimensions type size Location of Sensitive wire material leads OHWG112 12.8×4.5×4.2 Distance from bottom 2mm Plastic casing Tinned copper hard leads High temperature plastic soft wire OHWG113 11×φ3.6 Central axis Both ends are provided with magnetic beads OHWG113 A 12.8×4.5×4.2 Distance from bottom 2mm Plastic casing, Both ends are provided with magnetic beads Tinned copper hard leads OHWG115 9×6.5×7.5 Distance from bottom 3.2mm Plastic casing Tinned copper hard leads OHWG214 13×7.4×8 Distance from bottom 2.7mm Plastic casing with fixing hole Double color High temperature plastic soft wire OHWG311 11.5×φ4 Central axis Aluminum casing Tinned copper hard leads OHWG312 8.8×4.8×5.8 Distance from bottom 2.5mm Aluminum casing Tinned copper hard leads Nanjing Ouzhuo Technology co., Ltd Tel：86-25-52312738，86-25-83247886 Page 2 www.ohhall.com FAX: 86-25-52312738 www.zbling.com E-mail: [email protected] G Series OHW OHWG Wiegand sensor Wire bonding method Two leads of wiegand sensor can access to the post-stage signal processing circuit without distinguishing positive and negative. Dimension OHWG112/113A OHWG113 OHWG115 OHWG311 OHWG312 OHWG214 Trigger Mode and Installation Method Work with Magnetic Ring Nanjing Ouzhuo Technology co., Ltd Tel：86-25-52312738，86-25-83247886 Work with Bar Magnet Work with Magnetic Particle Page 3 www.ohhall.com www.zbling.com Work with Bar Magnet FAX: 86-25-52312738 E-mail: [email protected] G Series OHW OHWG Wiegand sensor Magnetic Circuit Design The right and reasonable magnetic circuit design is very important for the operation of wiegand sensor. 1) Dual magnetic poles ( N, S ) should trigger Alternately. The distance between poles should be close to or larger than the length of the sensor. For example, ferrite toroidal magnetic ring ( φ9.5 mm ) can be used in water meter, it also can apply a pair of alnico. The distance between the two poles should be not less than 9mm. 2) When installing magnet, make sure the direction of the magnetic line parallel to the sensor wire( refer to the triggering mode and the installlation method ) 3) The triggering magnetic flux density in the position of the Sensitive wire should between the min and max value in the characteristic list. In some application, such as calorimeter, the magnetic intensity should be the best value. Since the magnetic intensity will reduce with the increase of ambient temperature and the longer distance between the magnet and sensor. 4) Magnetic shielding is necessary to prevent ambient stray magnetic field interference. But the distance between shielding cover and magnetic ring or sensitive wire should be not less than 10mm, and no other magnetic materials, such as iron screw. Electric Circuit Designing In order to avoid some possible intreference and assure the accuracy of counting, some suggestions is offered as follows: 1)The output signal of Wiegand sensor should be shaped by wave shaping circuit first, and then input into the two tnterfaces Io1 and Io2 of single-chip microcomputer. After signal haping and amplification, there is a low output voltage similar to a rectangle on the output side Vo1 (note: it is not a negative pulse), and a high output voltage similar to a rectangle on the output side Vo2. Amplitude of the square wave is equal to supply voltage, and the width is 20 to 30μS. 2 When designing the software, make sure that counter plus "1" after collecting both low and high output voltage. That is meaning, the signal-chip microcomputer I 01 only need to collect the first low output voltage and ignore others. The same as the signal-chip microcomputer I 02 which only collect high output voltage. 3)The software can be used to recognize the output signals and interference signals, The Pulse Width of output signals are usually fixed, however the pulse width of interference signals are no rule. Nanjing Ouzhuo Technology co., Ltd Tel：86-25-52312738，86-25-83247886 Page 4 www.ohhall.com FAX: 86-25-52312738 www.zbling.com E-mail: [email protected] G Series OHW OHWG Wiegand sensor Typical Application Circuit Introduction Wave shaping circuit of sensor output signal ( as follows) can be used by electron flow meter directly. To improve the resistant ability to electromagnetic interferece, positive and negative signals are recommended to be adopted. s e n s o r Nanjing Ouzhuo Technology co., Ltd Tel：86-25-52312738，86-25-83247886 Page 5 www.ohhall.com FAX: 86-25-52312738 www.zbling.com E-mail: [email protected]