Bulletin No. MP-L Drawing No. LP0020 Released 02/10 Tel +1 (717) 767-6511 Fax +1 (717) 764-0839 www.redlion.net MAGNETIC PICKUPS & IN-LINE PREAMPLIFIER SIMPLE, RELIABLE & ECONOMICAL PULSE GENERATORS FOR: SPEED SWITCHES DIGITAL TACHOMETERS FREQUENCY TO D.C. CONVERTERS FEATURES INCLUDE SELF-GENERATING, NO EXT. POWER NEEDED WIDE OPERATING TEMPERATURE RANGE EPOXY ENCAPSULATED, MECHANICALLY RUGGED IMPERVIOUS TO DIRT, OIL & WATER NO MAINTENANCE REQUIRED LOW COST M12 CONNECTOR (MODEL SPECIFIC) on gears, definitions and relationships, see the Sensing Gears Bulletin. DESCRIPTION OF OPERATION The 1-Volt Threshold Speeds are based on a 0.005 air-gap. In applications A Magnetic Pickup consists of a permanent magnet, a pole-piece, and a where this air-gap cannot be maintained or where the air-gap can vary due to sensing coil all encapsulated in a cylindrical case. An object (target) of iron, eccentricity of the sensing gear, a correction factor can be applied from the steel, or other magnetic material, passing closely by its pole-piece causes curve in Fig 2. The effect of electrical loading is usually minimal at low speeds distortion of the magnetic flux field passing through the sensing coil and pole- and low output frequencies, however, output voltage drop due to loading at high piece, which in turn generates a signal voltage. The magnitude of the signal frequency or with low impedance inputs can be estimated based on the Output voltage depends on the relative size of the magnetic target, its speed of Impedance data. approach, and how close it approaches. The polarity of the signal depends on Note: Magnetic Pickups are used primarily for tachometer and other speed whether the target is moving toward or away from the pole-piece. related functions. They are not normally used for counting since loss of Magnetic Pickups are most frequently used to sense passing teeth on a gear, counts will occur at low speeds. Therefore, counters are not designed to sprocket, or timing belt wheel, to bolt-heads, key-ways, or other moving accept outputs directly from conventional magnetic pickups. In special machine mounted targets. Typical targets and resulting signal wave forms are applications where counting occurs only at running speed or where low- shown below in Fig. 1. speed count loss is acceptable, a Model ASTC can be used, or a different type of sensor can be used as a substitute. SELECTING A MAGNETIC PICKUP Selecting a magnetic pickup is a matter of matching a pickup to a gear (or other target), to provide enough input signal to a tachometer, speed-switch, or TYPICAL APPLICATION EXAMPLE other device for operation at the required minimum speed. The open-circuit A Digital Tachometer, with an input sensitivity of 0.25 V is to be used with a output from a magnetic pickup is directly proportional to speed, and once the Magnetic Pickup and gear to indicate speed down to 75 RPM. What are the minimum operating speed conditions have been met, excess signal will always alternative choices be available at higher speeds. Since the input voltage required by the tachometer is only 0.25 V, the surface The 1-Volt Threshold Speed column in the Application and Ordering Table speeds and reference gear RPMs required would only be 2 of the 1-Volt (next pg.) provides a convenient guide for estimating minimum operating Threshold Speeds listed. The MP-25TA with a 60-tooth, 24 D.P. reference gear speeds. This value is the linear surface-speed of a reference gear required to would obviously fall short since this combination will not develop 0.25 V until generate a 1-Volt peak, open-circuit output at an air-gap of 0.005 . The the reference gear speed reaches 250 RPM. reference gear listed for each pickup is near the optimum size for that pickup, The MP-37CA with the 60-tooth, 20 D.P. reference gear would both prove as defined by the criteria in Fig. 1B. The RPM listed is for a reference gear with suitable since they would deliver the required 0.25 V at 50 and 45 RPM 60 teeth running at that surface-speed. Gears with larger teeth provide about the respectively. They would also provide some additional margin for air-gap same or somewhat more output at the same surface-speed, while gears with variation. The curve of Fig. 2 shows a typical output drop of about 25% when smaller teeth or fewer number of teeth yield lower outputs. Figures 1C - 1F need the air-gap is increased from 0.005 to 0.0075 . Since the minimum operating a very high surface speed to generate a 1-Volt peak. The Minimum Gear Size speed in this application is 75 RPM, the additional sensitivity can be traded for column lists the Diametral Pitch size at which the output drops to 40-60% of the a wider air-gap allowance. output when the reference gear is used. Gears with very small teeth in relation The MP-62TA and MP-75TX with their respective reference gears would to the pole-piece diameter, deliver greatly reduced outputs, as shown in Fig. 1A. allow operation at even lower speeds. With both of these pickups it would be Threshold outputs when using targets other than gear teeth can be estimated by possible to drop to a smaller gear pitch for this application. their relative size with respect to the reference gear teeth. For more information 100 (A) (B) (C) (D) (E) (F) SMALL MAG. OPTIMUM POLE LARGE SHAFT BOLT CAM 75 GEAR PICKUP GEAR DIA.=d GEAR KEYWAY HEAD d d 3d 50 25 + LEADING LEADING EDGE EDGE 0 TRAILING TRAILING EDGE 0 5 10 15 20 25 EDGE - AIR GAP (INCHES x .001) FIG. 1 OUTPUT WAVEFORMS WITH VARIOUS TARGET SHAPES & SIZES FIG. 2 TYPICAL OUTPUT/AIR-GAP 1 OUTPUT VOLTAGE REL. OUTPUT %MAGNETIC PICKUP APPLICATION & ORDERING INFORMATION 1-VOLT MINIMUM TEMP. OUTPUT MODEL NO. DIMENSIONS THRESHOLD GEAR RANGE PART NUMBER IMPENDANCE SPEED (1) PITCH (2) C 0.687 0.01 0.313 135 in/sec 48 D.P. -40 to +107 130 20% MP25TA00 6.0 (17.45 0.254) (7.95) (152.4) 1000 RPM 15 mH REF. 0.040 (1.016) MIN. 28 AWG. DIA. POLE TIP 60T 24 D.P. MP-25TA VINYL LEADS Ref. Gear 0.02 (0.51) 1/4 -40 UNS-2A THREAD 0.812 0.01 0.439 6.0 33 in/sec 32 D.P. -40 to +107 340 20% MP37TA00 (20.62 0.25) (11.15) (152.4) REF. MIN. 200 RPM 44 mH 0.094 (2.387) DIA. POLE TIP 60T 20 D.P. MP-37TA 28 AWG. VINYL LEADS Ref. Gear 0.02 (0.51) 3/8 -24 UNF-2A THREAD 3/8 -24 UNF-2A THREAD PIN 3 33 in/sec 32 D.P. -40 to +107 340 20% MP37TAC1 PIN 2 0.094 (2.387) DIA. 200 RPM 44 mH * POLE TIP See Note 7 60T 20 D.P. MP-37TAC1 45 for pin-out 0.02 (0.51) PIN 4 information 0.812 0.01 Ref. Gear PIN 1 (20.62 0.25) 1.60 0.025 (40.64 0.635) +2.0 0.094 0.005 30 in/sec 32 D.P. -40 to +107 300 30% MP37CA00 8.0 -0.0 2.50 0.03 (63.5 0.76) (2.39 0.13) +50.8 (203.2 ) -0.0 180 RPM 65 mH DIA. POLE TIP MP-37CA MP37CA FLUSH WITH CASE 60T 20 D.P. 20 AWG. +0.000 +0.000 Ref. Gear 0.373 (9.474 ) -0.005 -0.127 VINYL LEADS 0.625 10 0 0.115 0.015 2.125 0.01 10 in/sec 24 D.P. -40 to +107 1200 20% MP62TA00 (53.98 0.25) (3048) (15.88) (2.92 0.38) 50 RPM 400 mH MIN. DIA. POLE TIP 24 AWG. MP-62TA 60T 16 D.P. VINYL JACKETED Ref. Gear SHIELDED CABLE 0.02 (0.50) 5/8 - 18 UNF-2A THREAD 2.00 0.01 0.02 (0.50) 0.625 (15.88) REF. 10 in/sec 24 D.P. -40 to +107 1200 20% MP62TAC1 (50.8 0.254) PIN 2 PIN 3 50 RPM 400 mH * 0.115 0.015 See Note 7 (2.92 0.38) MP-62TAC1 for pin-out 45 60T 16 D.P. DIA. POLE TIP PIN 4 information PIN 1 Ref. Gear 5/8-18UNF-2A THREAD 2.125 0.01 0.625 10 0 20 in/sec 24 D.P. -40 to +107 1200 20% MP62TB00 (53.98 0.25) (3048) (15.88) BLIND END SHELL MIN. 100 RPM 400 mH 0.106 (2.69) DIA. 24 AWG. MP-62TB EFFECTIVE POLE TIP 60T 16 D.P. VINYL JACKETED SHIELDED CABLE Ref. Gear 5/8 - 18 UNF-2A THREAD 1.25 1.875 36.0 (914.4) 30 in/sec 12 D.P. -73 to +93 230 20% MP75TX00 BLIND END SHELL (47.63) (31.75) LEAD LENGTH MIN. MP-75TX 100 RPM 100 mH 0.187 (4.75) 18 AWG. Explosion DIA. POLE PIECE 60T 10 D.P. FLEXIBLE LEADS Proof (3) Ref. Gear 0.5 INTERNAL PIPE THREAD 3/4 20 UNEF-2A THREAD Magnetic Pickup signal leads should never be run in conduit, troughs, or NOTES: bundles with other power or control voltage lines. 1) Surface speed of listed reference gear to produce 0.8 volt peak min., open- 6) Lead length of magnetic pickup should not be extended. An in-line pre- circuit output 0.005 air-gap. amplifier (ASTC) can be placed on the end of the provided length which 2) Gear pitch where output will drop to 40-60% of that generated by the would allow longer length after the in-line pre-amplifier. reference gear size, at the same surface speed. 7) M12 unit color codes for 1 meter cable is: 3) UL Listed CSA Certified, Class I Group A, B, C and D Class II Group E, F PIN 3 - Blue (-) and G. (AI-TEK Instruments) PN AIRPAX/70085-1010-005, UL File PIN 4 - Black (+) PIN 2 E40545 (N), CSA File 042648. PIN 3 PIN 2 - NC N.C. 4) Polarity, all pickups: white output lead goes positive with respect to black - PIN 1 - NC when target approaches pole. 45 5) 2-Wire shielded cable is recommended for all magnetic pickup outputs. PIN 4 Connect the shield to the COMMON or GROUND terminal of the PIN 1 + instrument being used and leave the shield un-connected at the pickup. N.C. ORDERING INFORMATION The following cables are for use with magnetic pickups MP37TAC1 and MP62TAC1, which have M12 connectors. MODEL NO. DESCRIPTION PART NUMBERS CCM Mating Cable With M12 Connector, 1 Meter In Length CCM12S01 Red Lion Controls Red Lion Controls India China Red Lion Controls Red Lion Controls 54, Vishvas Tenement Unit 101, XinAn Plaza Headquarters Europe GST Road, New Ranip, Building 13, No.99 Tianzhou Road 20 Willow Springs Circle Printerweg 10 Ahmedabad-382480 Gujarat, India ShangHai, P.R. China 200223 York PA 17406 NL - 3821 AD Amersfoort Tel +91 987 954 0503 Tel +86 21 6113-3688 Tel +1 (717) 767-6511 Tel +31 (0) 334 723 225 Fax +91 79 275 31 350 Fax +86 21 6113-3683 Fax +1 (717) 764-0839 Fax +31 (0) 334 893 793 MP37TAC1 MP62TAC1 MP37TA MP25TA MP62TA MP62TB00