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Related Manuals for Lascar DPM 160
Summary of Contents for Lascar DPM 160
- Page 1 Panel Instrument Application Notes Issue 3...
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Page 2: Table Of Contents
TABLE OF CONTENTS Table of Contents Installation and Operation - Section A 1. Basic Principles .............................3 The A to D Converter ..........................3 Multiplication & Division ...........................4 Specification ..............................4 Analogue Inputs ............................6 Differential Input ............................6 Differential Reference ..........................6 Analogue Common ..........................6 Common Mode Rejection Ratio CMRR ....................6 Eliminating Common Mode Errors......................7 3. -
Page 3: Installation And Operation - Section A
1.1 THE A TO D CONVERTER The vast majority of Lascar meters operate using the Dual-Slope method of conversion. Put simply, the technique involves charging a capacitor (CINT) (CINT) from zero at a rate directly proportional to the input voltage and for a fixed time (see fig. 1.2). This is the integrate phase. Then the control The vast majority of Lascar meters operate using the Dual-Slope method of conversion. -
Page 4: Multiplication & Division
VREF VREF The DPM 160 achieves either 200mV or 2V full scale reading (for a 1V reference) by digitally selecting either 10000 or 1000 clock pulses during the signal integrate period. Thus for a DPM 160 in 200mV scale:- READING = 10000 x VIN (1.3) - Page 5 PANEL INSTRUMENT APPLICATION NOTES Installation & Operation - Section A 1.3.2 4 ½ Digit Instruments DPM 160 uses the ICL 7129A TABLE 2 - ICL 7129 SPECIFICATION. l l u t f i ° 0 < < ° 0 µ...
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Page 6: Analogue Inputs
PANEL INSTRUMENT APPLICATION NOTES Installation & Operation - Section A 2. Analogue Inputs Differential Input The analogue inputs for VIN (IN HI and IN LO) respond to the voltage between them and not their voltage with respect to any other signal. Because of this, the inputs are said to be “differential”. -
Page 7: Eliminating Common Mode Errors
PANEL INSTRUMENT APPLICATION NOTES Installation & Operation - Section A Thus for a 4½ digit display the offset will only be a fraction of one count (with 200mV FSR the least significant digit records 10‘s of mV) Earlier designs of panel meter circuits used COM as the ground reference during integration. These had a lower CMRR of typically 86dB and ideally Installation Operation - Section A &... -
Page 8: Noise
V IN CIRCUIT IN LO WRONG UNDER REF LO TEST PANEL INSTRUMENT APPLICATION NOTES Fig 3.2 Errors due to supply impedances If we redraw fig 3.1 we will see that small impedances (Rs) in power supply lines will cause a volt drop (Vs) which will be subtracted from the reading, causing an offset. -
Page 9: Interfacing With Linear And Digital Circuitry
IN LO IN LO TEST (TEST) 4.1.3. SINGLE ENDED METER OPERATION Many Lascar meters generate their own negative supplies internally. Input POWER All LED meters do and so do all S-type LCD meters. These supplies Fig. 4.2.a Using COM to generate signal ground Fig. -
Page 10: Digital Signals
Fig. 4.2.c Buffering the ground. 4.1.3. Single Ended Meter Operation 4.1.3. SINGLE ENDED METER OPERATION Many Lascar meters generate their own negative supplies internally. Many Lascar meters generate their own negative supplies Input POWER All LED meters do and so do all S-type LCD meters. These supplies IN HI internally. -
Page 11: Power Supplies
(see sections 6). All mains powered meters have internal isolated supplies. Lascar manufacture a number of small PCB based supplies which are suitable for powering All mains powered meters have internal isolated supplies. Lascar manufacture a number of small PCB based supplies which are suitable for powering supply should be isolated. -
Page 12: Fitting An External Reference
8. LCD BACKLIGHTING Several Lascar LCD displays feature LED backlighting. This is an option on the DPM 1, 2, 3, 100, 125, 500 and standard on the DPM 700 and the 900 series. The DPM 100, 500 and 900 series lamps operate from 5V d.c.. The DPM 700 is supplied with either 5V or 9V backlighting. The 900 series will take 50mA (nominally) from the supply but can be supplied at up to 90mA from a higher voltage, provided care is taken to limit the current. -
Page 13: Commissioning The Meter
Installation & Operation - Section A Lascar meters do not normally need special handling precautions but they do contain CMOS circuitry and static should be avoided. When soldering, use irons with earthed tips and avoid applying excessive heat to the meter's PCB. The recommended tip diameter should be between 1 and 2mm and flat, not pointed. - Page 14 PANEL INSTRUMENT APPLICATION NOTES Installation & Operation - Section A Installation Operation - Section A & Installation Operation - Section A & Fit the bezel to the front of the panel and then locate the Fit the bezel to the front of the panel and then locate the meter into the bezel from behind.
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Page 15: Using Pcb Links
9.4 USING PCB LINKS Many Lascar meters have programming pads to make circuit configuration quick and easy. Some pads are almost always closed by the customer and in Many Lascar meters have programming pads to make circuit configuration quick and easy. Some pads are almost always closed by the customer Many Lascar meters have programming pads to make circuit configuration quick and easy. -
Page 16: Typical Applications - Section B
PANEL INSTRUMENT APPLICATION NOTES Typical Applications - Section B Typical Applications - Section B Typical Applications - Section B 1. MEASURING VOLTAGE 1. MEASURING VOLTAGE 1. Measuring Voltage Because all meters measure d.c. voltage this is the simplest parameter to measure. The most common interface circuit is a voltage attenuator. Fig. 1. Because all meters measure d.c. - Page 17 PANEL INSTRUMENT APPLICATION NOTES Typical Applications - Section B Typical Applications - Section B Always ensure IN LO is not connected to COM. Fig. 2.b. gives the preferred application for LED and S-type LCD meters. Always ensure IN LO is not connected to COM. Fig. 2.b. gives the preferred application for LED and S-type LCD meters. µ...
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Page 18: Measuring Resistance
DPM 45, DPM 850S, EMV 1125, SP 100 and SP200. Alternatively the DMM 939 is available where resistors etc are already provided on-board. LCD 3½ LED 3½ LCD 4½ DPM 1 DPM 340 DPM 160** DPM 125 DPM 390 DPM 300** DPM 1760 DPM 959... -
Page 19: Thermometer Circuits
4. THERMOMETER CIRCUITS The simplest way is to use a Lascar panel mounted temperature meter (DTM 995 or EMT 1900). However it is also possible to use a DPM with front The simplest way is to use a Lascar panel mounted temperature meter (DTM 910, DTM 995 or EMT 1900). However it is also possible to use a DPM The simplest way is to use a Lascar panel mounted temperature meter (DTM 910, DTM 995 or EMT 1900). -
Page 20: Using Strain Gauges
PANEL INSTRUMENT APPLICATION NOTES Typical Applications - Section B Typical Applications - Section B Typical Applications - Section B 5. USING STRAIN GAUGES 5. USING STRAIN GAUGES 5. Using Strain Gauges The strain gauge circuit is a variation of the resistance circuit as seen in section 3 above. It gives a reading of bridge imbalance as a ratio of the applied The strain gauge circuit is a variation of the resistance circuit as seen in section 3 above. -
Page 21: Ac-Dc Converters
RMS values. The second is the true RMS converter. This can give the true The simplest way is to use a Lascar panel mounted AC meter (DPM 970). However it is also possible to use a DPM with front end circuitry. Two basic The simplest way is to use a Lascar panel mounted AC meter (DPM 970). -
Page 22: Autoranging
Fig. 9 Measuring Frequency www.lascarelectronics.com Issue 1_10-2016 Page 22 of 22 Lascar Electronics Limited Lascar Electronics, Inc. Lascar Electronics (HK) Limited Tel: +44 (0)1794 884567 Fax: +44 (0)1794 884616 Tel: +1 (650) 838 9027 Fax: +1 (650) 833 5432 Tel: +852 2797 3219...