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Questions tagged [precision]

Use this tag to indicate that the topic is related to achieving the highest precision for a circuit. Examples include using 1% resistors instead of 5% or 10%. This tag also can be used in relation to measuring precision in a finished circuit.

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53 views

Paralleling Multibit current DAC: Improving Accuracy by Averaging

No doubt that if I put in parallel n DACs, multibit (i.e. 16 bit) current output R2R ladder chips, I get n-times higher current at the summing node and the output impedance is also reduced by "n". ...
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1answer
48 views

{enc28j60} Is the 50ppm crystal good enough

I have some 25MHz 50ppm crystals but I am not sure if they are good enough to be used with ENC28J60.
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1answer
100 views

Significant DC current on precision DMM despite not being connected to anything

Disclaimer: I'm not a EE professional (I have a background in physics though), so please bear with me if the question seems banal, obvious or just plain stupid. We have a Keysight 34465A DMM, which, ...
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2answers
27 views

Determining equivalent resistance to find the cutoff frequency

I am designing a low noise circuit for a precision application and require a stable voltage supplied to the circuit. I have determined that the MAX6250 voltage reference best suits my circuit. A ...
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1answer
173 views

Precision Adjustable Voltage Reference

Can a low-cost, low-resolution RDAC and a precision voltage reference by used to make a coarsely adjustable high-precision DC voltage reference? Consider for example the AD5121 7-bit RDAC with ±5ppm/°...
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67 views

Measurement of high voltage with low voltage circuit

Is it possible to make a high-impedance, precision measurement of a 10V DC signal (dynamic range requirement is only ±1V with a DC-1kHz BW) using amplifiers and an Sigma-Delta ADC supplied only by +3....
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2answers
168 views

Low-pass Filter with zero drift amplifier

Can an auto-zero or chopper amplifier be used in a low-pass filter to remove a high frequency carrier? I am trying to design an active low-pass filter with a 1kHz cutoff and very low DC drift, offset, ...
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2answers
142 views

Is this normal for a 12 bit Microcontroller ADC (STM32F303)?

I am using an STM32F303 with a 12bit ADC to read an output voltage using the ِADC itself.. as far as I know the Vref of the ADC is the same as the VDD of the device. Am I right? However, when feeding ...
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1answer
82 views

Dictionary: is PWM precision the same of PWM resolution?

I have an issue in identifying the meaning of PWM precision. I've always talked about PWM resolution, and to me seems to be 1/2^(n-1). Is the precision of the PWM just prequency precision? Or is the ...
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2answers
116 views

Is the HP206C really so precise?

I'm looking for barometer sensors for use in Arduino projects. One of the items I consider is the HP206C (at Reichelt, Germany). The vendor contradicts himself a little bit when he mentions 0.1 m and ...
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0answers
71 views

Would a current feedback op-amp work well as a precision ground reference?

I've been looking into precision ground reference circuits to form ±5V rails from a 10V supply for a project I'm working on, and noticed that current feedback (CFB) op-amps have some desirable ...
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1answer
83 views

How precise resistor value needed in feedback?

I'm trying to design an isolated feedback loop for a Flyback converter using TLV431 and an optocoupler. One of the TLV431 pins is the reference voltage, where the output's resistor divider (R1 and R2) ...
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2answers
109 views

Wide range and high precision current measurement

I need to measure current over a large range from a few µA up to 2A. The application is sensitive to noise at later calculations with the measured current. My idea is to use different shunt resistors ...
2
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2answers
180 views

Confusion about accuracy vs tolerance of an operating resistor

Let's say I bought a 100 Ohm resistor from a manufacturer with a tolerance of 10%. What I understand from the term tolerance here is that: it is the amount that a resistor may initially vary from its "...
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3answers
189 views

Precision of ADC

While I was studying for my exam I saw this question where he's given me a bunch of ADCs asking me which would work and which wouldn't He's given me the Minimum required Precision for the ADC and I ...
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2answers
52 views

How to synchronize two different precision measurement instruments?

I am trying to design a turbidity detector and this has to be sensitive to tiniest amounts of contamination present in a sample fluid. My setup consists of a 780nm laser whose current I control with ...
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2answers
86 views

Automated voltage measurement: Tradeoff between PLC and averages

I am setting up an automated voltage measurement of a precision device. In my case, I am using a Keithley 2000 and controlling it over RS232 from MATLAB. The voltages I am measuring have to be quite ...
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1answer
98 views

Single Ended Precision Variable Amplitude Square Waves and Charge Injection

I love to hear any thoughts about a good break-before-make analog switch with low charge injection or even even better any thoughts on generating precision amplitude square waves in general. As to ...
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1answer
397 views

Potentiometer minimal turning for high resolution

I have a 1 turn 10k Ohm Potentiometer attached to the analog input of an Arduino. Now, the full range of the pot gives me values from 0 - 1023, nothing new. The problem: I only want to measure ...
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3answers
276 views

Do the temperature coefficients of the resistors in the LM399/LM199 “Portable Calibrator” significantly effect the output stability?

I'd like to know how voltage reference stability is obtained in products like 6.5 digit multimeters that use LM399 as a voltage reference in spite of using two gain resistors. Let's assume an ideal ...
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1answer
92 views

Precision of estimating power consumption with a current sensor

When estimating power consumption with a current sensor, what is the usual precision that can be achieved for home appliances? I'd like to make a simple circuit using such a sensor and a ...
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3answers
76 views

Measuring ripple voltage using on-board components. Is it possible?

I am designing a circuit with a very sensitive analog part. In order to eliminate SMPS noise from a regular power supply, the device has its own non-SMPS power supply followed by an ultra low noise ...
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5answers
4k views

*Very* high precision, *very* stable current source

My background: experimental physics. Not an electrical engineer, but I have some experience putting together basic electronic circuits for physics experiments. So please be kind and explain as if I'm ...
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5answers
4k views

Why do some EMI/RF shields have holes on the top and some don't?

I am not talking about cutouts for tall components. I don't think they are for ventilation as they are often covered with manufacturer labels.
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1answer
690 views

What is a 4-wire voltage measurement?

I am working with a Fluke 8508A, an 8.5-digit table-top multimeter. To my surprise, one of the menu options is a 4-wire DC voltage measurement. I know how 4-wire resistance measurements work, but I ...
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4answers
322 views

Power supply for battery powered application with precision ADC

I’m designing battery powered application in the form of a sensor with an onboard high-precision (20 to 24 bit) sigma-delta ADC that measures a couple of load cells in a Wheatstone bridge. My question ...
2
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1answer
195 views

If I have 5% 100k resistors but wanted 1% precision, can I use 4 of them in series parallel to improve on the 5% precision? [duplicate]

I made an error on ordering and am receiving a shipment of 5% 100K resistors when I wanted 1%. This is for a voltage divider circuit. Would it help improve the precision if I put two each in ...
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1answer
2k views

DC motor RPM accuracy/precision

Small, permanent magnet, brushed tri-phase DC motors ('toy motors') may give a speed/torque curve, or at minimum a no load RPM. What is typical RPM accuracy relative to the datasheet, and how precise ...
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192 views

unstable magnetometer readings

I did the magnetic calibration here on the LSM303DLHC for a field roughly 48 uT. The method seems to have worked in that the combined bias (b) values went from ...
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3answers
260 views

SMD precision resistor color code (0805)?

We have specified some 0805 resistors to be 0.2ppm/C. On some boards/batches these are green. On others more "normal" looking. We specified Vishay. Is there some color code that indicates ultra-...
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5answers
861 views

Determining the current from an infrared LED used as photodiode

Let me talk in general first: I have two LEDs of the same wavelength (940 nm) placed opposite to each other. Between them is a 140 mg/dL glucose solution (only glucose + water). One LED is ...
3
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3answers
1k views

How to calibrate opamp to eliminate input offset/bias current and offset voltage?

I am doing on a project using opamp OP07 to amplify a current. Here is my schematic: The problem is, the output I obtained is not highly precise as I expected. For example in the figure above the \$ ...
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2answers
137 views

Precision with opamp in transimpedance amplifier configuration with LED as photodiode

I found this circuit in searching for a circuit that uses LED to measure absorbance What I want to ask is: in order to "accurate" the readings from \$ V_{out} \$, for example: assume that the current ...
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1answer
296 views

precision current sink for battery discharge

I'm trying to build a precision computer-controlled current sink to discharge a battery. The maximum discharge current is to be 2mA (at the moment; I might go to larger currents later) and the battery ...
0
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1answer
79 views

Component manufacturing and placement accuracy/precision

I am involved in a community project where I need to employ computer vision on common smartphone models (Samsung Galaxy S 5/6/7, iPhones etc.). Doing that involves calibrating the phone's camera for ...
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3answers
217 views

Precise Clock Signal

I'm working on a project where i try to make a normal clock.Everything is finished and ready except for the main signal coming from the oscillator. I'm making a relaxation oscillator of course but i'v ...
1
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1answer
336 views

Voltage regulator or reference for a Wheatstone bridge excitation voltage?

I will have a circuit which will be amplifying a Wheatstone-bridge(strain gage) signals by an instrumentation amplifier. I read that the noise of a Wheatstone-bridge(strain gage) has very much to do ...
0
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1answer
369 views

LiFePO4 16-cell stack precision dc volt measurement LTC2400 MUX

I would like to build a highly precise volt meter (5 digits; e.g. +/- 1mV) to measure each cell voltage in a LiFePO4 battery stack of 16 cells (<60V). I am content with measuring the cell between 3 ...
3
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1answer
249 views

How do I find capacitors for low dielectric absorption?

I'm looking through digikey's option on polypropylene capacitors. None of them seem to specify dielectric absorption. This is for a low voltage sample-hold circuit. Low leakage is good, but low ...
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0answers
85 views

Simultaneous Cathodic Protection and 4 Wire Resistance Measurement

I am making an electrical resistance sensor for erosion rate measurement using the Arduino. Since my sensing element is a thin strip of carbon steel, I have to ensure that it is protected from ...
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3answers
187 views

Cheap precision sense resistor

I need a precision low value sense resistor to make current measurements e.g. 10R 0.01R. Looking for precise resistors e.g. Vishay, show that these are expensive e.g. $35 for a single 0.001-0.005% ...
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3answers
367 views

Measuring mOhm resistance using LT006 precision amplifier and 4-Wire Method

I am trying to use the 4-wire method to measure the resistance of small strip of carbon steel, which will have a resistance of about 0.3 mOhms. I am currently trying to test my circuit with a known 0....
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3answers
583 views

Electrometer amplifier circuits - surface mount or traditional

I have looked at a number of electrometer amplifiers and they all seem to use big through hole passive components and through hole DIL packages. Is there a reason for not using surface mount?
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2answers
68 views

Instrumentation: Measurement Noise

I have a Tektronix DPO2014 and I'm trying to get a feel for what I can expect in terms of precision and accuracy performance on a clean and stable voltage. I'd like to be able to accurately and ...
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0answers
184 views

The precision of internal voltage reference in PIC

I am designing some circuit with PIC16F18345 and I need some voltage reference (±0.5% or better). I can add some external reference or use built-in internal voltage reference in that MCU (that means ...
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2answers
562 views

Measuring the precision of a clock

I have worked on a project using high precision clocks for some time now. I have yet to find a clear description on how manufacturers and scientist confirm and verify the precision of clocks like ...
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2answers
109 views

How repeatable is the output from an opamp

I'm having difficulties finding information on how repeatable the output of an opamp in this simple comparator configuration is. Give the following schematic: simulate this circuit – Schematic ...
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4answers
2k views

Multimeter precision on low battery

Recently I measured some voltages with my cheap digital multimeter while it was showing the low battery indicator. Later I purchased a replacement battery and decided to redo my measurements. I found ...
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1answer
986 views

Very precise way of measuring small distances?

I am looking for a somewhat cheap way of measurin small distances ( >0.1 inch) between an object and a sensor, are there any good ways to do this? I am considering the component from a flatbed scanner,...
3
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1answer
986 views

Ceramic capacitors microphonic bandwidth

I need to use some relatively high value (10uF) capacitors in a discrete switched capacitor circuit and I need them to precisely store their voltage for a small amount of time (about 5us). The ...