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Tytuł: Pomiar prądów faz silnika krokowego przez oscyloskop dwukanałowy Wiadomość wysłana przez: markcomp Lutego 03, 2011, 03:47:48 Pomiar prądów faz silnika krokowego przez oscyloskop dwukanałowy
jak równocześnie oglądać wykresy prądów faz?... trzeba jakoś oddzielić masy kanałów oscyloskopu (takiego tańszego bez separacji kanałów)... gotowe sondy do separacji kanałów są DROGIE... optoizolacja jest trudna do realizacji... można próbować zastosować wzmacniacz operacyjny... w celu odsymetryzowania sygnału napięciowego z rezystora do pomiaru prądu fazy... (http://freecircuitdiagram.com/wp-content/uploads/2010/09/Differential-Current-Sensing-Inside-H-Bridge.gif) http://freecircuitdiagram.com/2010/10/02/differential-current-sensing-inside-h-bridge/ datasheet ad8205 http://www.autex.spb.ru/ad/AD8205.pdf można zapewne próbować "obtanić" projekt przez zastosowanie normalnego wzmacniacza + rezystory o większej precyzji (tak jak to widać w datasheecie ad8205) ciekawe czy można to zrobić inaczej? Tytuł: ISO122 Wiadomość wysłana przez: markcomp Lutego 07, 2011, 11:24:03 ISO122
Precision Lowest Cost ISOLATION AMPLIFIER FEATURES 100% TESTED FOR HIGH-VOLTAGE BREAKDOWN RATED 1500Vrms HIGH IMR: 140dB at 60Hz BIPOLAR OPERATION: VO = ±10V 16-PIN PLASTIC DIP AND 28-LEAD SOIC EASE OF USE: Fixed Unity Gain Configuration 0.020% max NONLINEARITY ±4.5V to ±18V SUPPLY RANGE APPLICATIONS INDUSTRIAL PROCESS CONTROL: -Transducer Isolator, Isolator for Thermocouples, -RTDs, Pressure Bridges, and -Flow Meters, 4mA to 20mA Loop Isolation GROUND LOOP ELIMINATION MOTOR AND SCR CONTROL POWER MONITORING PC-BASED DATA ACQUISITION TEST EQUIPMENT DESCRIPTION The ISO122 is a precision isolation amplifier incorporating a novel duty cycle modulation-demodulation technique. The signal is transmitted digitally across a 2pF differential capacitive barrier. With digital modulation the barrier characteristics do not affect signal integrity, resulting in excellent reliability and good high frequency transient immunity across the barrier. Both barrier capacitors are imbedded in the plastic body of the package. The ISO122 is easy to use. No external components are required for operation. The key specifications are 0.020% max nonlinearity, 50kHz signal bandwidth, and 200mV/°C VOS drift. A power supply range of ±4.5V to ±18V and quiescent currents of ±5.0mA on VS1 and ±5.5mA on VS2 make these amplifiers ideal for a wide range of applications. The ISO122 is available in 16-pin plastic DIP and 28- lead plastic surface mount packages. http://focus.ti.com/lit/ds/symlink/iso122.pdf Tytuł: Sensor interface DIL-16, UTI-DIL16 Wiadomość wysłana przez: markcomp Lutego 07, 2011, 11:39:41 Sensor interface DIL-16, UTI-DIL16
Universal Transducer Interface (UTI) Revolution in Sensor Interfacing Features · Provides interfacing for many types of sensor elements: capacitors, platinum resistors, thermistors, resistive bridges and potentiometers · Measurement of multiple sensor elements · Single 2.9 V - 5.5 V power supply, current consumption below 2.5 mA · Resolution and linearity up to 14 bits and 13 bits · Continuous auto-calibration of offset and gain · Microcontroller-compatible output signal · Tri-state output · Typical measurement time 10 ms or 100 ms · 2/3/4-wire measurement available for almost all measurements · AC excitation voltage signal for all sensor elements · Suppression of 50/60 Hz interference. · Power down mode · Temperature range -40ºC to 85ºC · Die operating temperature up to 180ºC 1. General Description The Universal Transducer Interface (UTI) is a complete analog front end for low frequency measurement applications, based on a period-modulated oscillator. Sensing elements can be directly connected to the UTI without the need for extra electronics. Only a single reference element, of the same kind as the sensor, is required. The UTI outputs a microcontroller-compatible period-modulated signal. The UTI can provide interfacing for: · Capacitive sensors 0 - 2 pF, 0 -12 pF, variable range up to 300 pF · Platinum resistors Pt100, Pt1000 · Thermistors 1 kW - 25 kW · Resistive bridges 250 W - 10 kW with maximum imbalance +/- 4% or +/- 0.25% · Potentiometers 1 kW - 50 kW · Combinations of the above mentioned The UTI is ideal for use in smart microcontroller-based systems. One output-data wire reduces the number of interconnect lines and reduces the number of optocouplers required in isolated systems. Continuous autocalibration of offset and gain of the complete system is performed by using the three-signal technique. The lowfrequency interference is removed by using an advanced chopping technique. The function selection can be configured in both software and hardware. https://www1.elfa.se/data1/wwwroot/assets/datasheets/07308836.pdf |