Questions tagged [sensor]

Sensors convert a physical quantity (e.g. temperature, pressure) into an electrical signal.

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35 views

How do I correctly calculate my magnetometers hard iron bias?

Im using a LSM9DS1 9DOF IMU and I want to calibrate the magnetometer. Im reading the raw data, saving the min/max values for each axis while rotating it for like a minute across each axis. I calculate ...
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2answers
38 views

Break beam sensor to replace piezo transducer

I have a device intended to sound an alarm and flash a bright light when it detects a phone ringing (so you can hear the phone ringing in noisy environments like workshops). I want to repurpose it to ...
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1answer
39 views

Read proportional voltage with optoisolator with no ground loops

I have a variable output 0-5V which comes from a sensor and I would like to read it by using the analog input provided by my motor controller. The problem is that I need to avoid ground loops and so I ...
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1answer
85 views

Why don't commercial metal detectors clearly distinguish between iron and other metals?

I've read about how metal detectors work, and what I learnt here on EE.SE and other articles, the main principle is that ferrous metal will increase the inductance of the search coil, while non ...
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3answers
72 views

measurement errors: add up or cancel out?

Take an accelerometer, or a hall sensor, or a thermometer, or any sensor. It will have an accuracy, which means the readings will contain some error of this sort. My guess is that by taking a big ...
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34 views

How to write the algorithm for counting of coil in a machine on basisof sensor [closed]

I am stuck with two questions. I need to write the algorithm for generation of a coil on my sensor basis; i.e, if the sensor is on and the force is greater than 10kN and speed is greater than 2 m/min,...
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1answer
33 views

Saturation of Constant Temperature Anemometer

Continuation of this question, apologies for the schematic. Rwire and Roh are depicted in balanced state. This is a common Constant Temperature Anemometer circuit, however the diff amp output (...
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84 views

Distance monitoring under water

I would like to continuously monitor the position of a metal object that moves vertically up and down in the water, I have to place the sensor under the valve, by 20cm and measure through a small hole....
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1answer
31 views

Unvalid output voltage of LM35 temperature sensor

I have connected once the Vss and Ground of my LM35 sensor reversely wrong. After correction of this, the output voltage is 0.5 V which seems to be invalid in room temperature. I'm not sure if the ...
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1answer
41 views

Sensor Error Adjustment

I have been asked to improve the high end accuracy of a pressure sensor (Without modifying hardware). I have collected data from 30 samples and found a trend to the error. My question now is if it is ...
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0answers
25 views

How does one use Intel's ISH (integrated sensor hub) interface? [migrated]

I am interested in exploiting the integrated sensor hub on my single board computer (an Up Core). However, it is unclear as to what parts I can use and whether the drivers for this hardware already ...
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1answer
38 views

LVDT Measurement question

Is there any reason one might want to measure both the primary and secondary coils on an LVDT? I assume the primary coil excitation voltage would be constant, but I see circuits around that measure ...
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42 views

Why does my MAX30105 give wrong temperature reading?

I am using a custom made board for the MAX30105 sensor. I am checking with ESP8266 Arduino (Sparkfun max301505 library.) When the sensor is on, the temperature reading is 10 Celcius. It ...
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1answer
34 views

How to get a serial reading from an Ultrasonic Rangefinder on a Raspberry 3 B+?

I'm trying to set up a Maxbotix Ultrasonic Rangefinder (LV-EZ0) with a Raspberry Pi 3 B+. I've tried all the tips I could find: raspi-config disable serial interfacing for shell, but keep it on ...
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1answer
36 views

Understanding Plot Showing Impedance, Resistance, and Reactance

I am looking at part of the datasheet for a hydrophone I am using in a project. It includes this figure, which plots resistance, impedance, and reactance vs. frequency: Part of my project involves ...
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2answers
59 views

VL53L1X Time of flight sensor field of view implications

VL53L1X is a Time of Flight sensor, it measures distance via pulsed laser or so I understand. But upon reading its specs it has a field of view of max 27 degrees which is quite confusing for me. I ...
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2answers
63 views

Use magnetic field to estimate distance - best sensor type

I want to measure the position of something that movies along a single axis over a range of 150mm at a frequency of roughly 1kHz. You can imagine that it is the piston on a shock absorber. I could ...
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1answer
86 views

Trouble starting a Constant Temperature Anemometer

I made a Constant Temperature Anemometer using this and this as reference. However, I'm having trouble in making it work properly. To get the circuit started I need the emitter voltage (Bridge Top) to ...
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40 views

Designing a wireless network of sensors

I'm designing a network of wireless sensors for an outdoor enviroment. It will consist of aprox. 30 sensors powered by battery (6 months autonomy), taking measurements with a low frequncy (max 10 ...
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1answer
46 views

STM32L0x1 incorrect temperature reading

I'm having trouble reading the temperature, its values are incorrect. The temperature in the room is 22C and the temperature of the sensor shows 55C (selfheating and the measurement error cannot be ...
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1answer
22 views

Static and dynamic behaviour of a sensor

On a slide, i read that i can model the static behaviour of a sensor as: whereas it's dynamic behaviour as: Is correct to say that the static behaviour is the steady-state behaviour, while the ...
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1answer
38 views

capacitance vs impedance measurement

I've been trying to design precise distance measurements similar to the digital caliper or dial micrometer for my CNC project by capacitance sensing between prob and base metal. I can connect base ...
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1answer
42 views

How can I override a capacitive touch on-off switch? [closed]

I bought a floor lamp for use with a mechanical timer that turns electricity on and off using a set schedule (for example, when you're away but want to convince others that you're still at home). ...
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10answers
3k views

Best practice in transmitting sensor analog signal over longer distances (approx. 100') — in cost sensitive products for microcontrollers

I'm looking for best practices for transmitting an analog sensor signal over long distances to a microcontroller such as the Arduino running at 3.3v or 5v. Keeping costs low is imperative. SPI and ...
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1answer
38 views

How do I read a simple touch sensor value from Arduino? [closed]

I suppose instead of connecting to the LED it will connect to A3 on the Arduino for example but I'm having a hard time making it work. I don't know which point on the circuit should be connected to ...
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1answer
48 views

Ebike brake lever cutoff switch / interrupt switch : How does it work? [closed]

When pressing the brake lever on my ebike the BLDC motor controller (aka ebike controller) 'cuts power' to the motor until the brake lever is released again/sensor is deactivated. I would love to know ...
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0answers
38 views

Open circuit showing 1-15MΩ of resistance on multimeter

I'm trying to understand a phenomenon I observed while troubleshooting a system. There are airflow sensors with wires connected to common and normally open so that the circuit closes when air is ...
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1answer
108 views

Why are capacitors used parallel to transistors

In the circuit attached. There are two capacitors. One is parallel to "PWR LED". Although I understand it delays the turning on and off of the LED, why would you need that? Also, the other capacitor ...
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1answer
29 views

Capacitor on sensor output purpose

I'm currently using a demo-board from sparkfun for quick prototyping of a hall-effect sensor application. The specific chip I'm using is the ACS723-5AB, a Hall-Effect sensor that can measure between -...
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1answer
45 views

Sharing a single ground wire across multiple RTDs

Consider the following, simplified schematic for a single, two-wire RTD sensor: simulate this circuit – Schematic created using CircuitLab The two wires from the RTD sensor plug into pins 1 ...
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0answers
55 views

Inductive toroidal conductivity sensor doesn’t work with enclosure on toroidal inductor

I’m building a inductive conductivity sensor using the principle shown in this image. I built a 4khz sine wave generator and connected it with the drive coil and look at the voltage across the pickup ...
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0answers
38 views

ESP12e: analog reading not working with voltage divider

I'm trying to read from an analog sensor (a capacitive soil moisture sensor). I'm using a ESP12E, not a development board, so the ADC pin can only take 1V max. Since my sensor can output up to 3V, I ...
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4answers
872 views

A passive sensor does not need any additional energy source?

I am currently studying the textbook Handbook of Modern Sensors - Physics, Designs, and Applications, fifth edition, by Jacob Fraden. In this textbook, the author states the following: All sensors ...
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43 views

Ball impact and distance sensor

I am new to electronics, and a professional programmer. I want to develop a sports IoT App and for this app, I need to detect how far a ball hits the ground from the sensor. There can be other ...
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1answer
35 views

Recommendation on Optical Sensor (being used for Fingerprint Scanning)

When I have researched available optical fingerprint sensor modules, every one comes with a processor that takes the sensor image data and processes it. They all appear to keep the fingerprint data ...
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1answer
40 views

hall current sensor potential failure mode

I was curious what are potential common failure modes for hall-based ac current sensors in a mains ac environment? Specifically those like the acs712 and acs723. Assume you have a 5amp current sensor, ...
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1answer
58 views

infrared and K-Type temperature sensors badly disagree [closed]

They are both cheap. There is a piece of PCB balanced on top of the K-type thermocouple's probe; there is also a red laser light from the infrared thermometer right in the middle of the same PCB where ...
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1answer
35 views

Possible to measure EEG signals with an AM receiver antenna/circuit?

I'm having trouble understanding the importance of placing EEG electrodes directly on the skin. I used to think the reason for this was to pick up voltage differences between points on the skull, the ...
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1answer
29 views

Force-Sensitive Resistor Break When Pressure is Constantly Applied

My question is mainly the following: Is there a force-sensitive resistor that can handle pressure (like 50kg weight) constantly on it? While not having its response curve altered because of this? ...
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1answer
87 views

Running out of I2C channels on microcontroller [closed]

I am building a signal acquisition system that has a lot of sensor. These sensors communicate with the microcontroller by I2C interface. I'm running out of I2C channels on the microcontroller. Is ...
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0answers
39 views

STM32duino can't detect MPU6050

I'm currently trying to read values from an MPU6050 using an STM32duino, but using an I2C scanner code, the STM32 can't detect the sensor. I've checked all the connections using an avometer and it all ...
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2answers
81 views

Humidity sensor connection “HIH-4000”

Why do we need a load resistor connected between the output pin and ground? reference to a detailed description of the sensor
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2answers
88 views

How to mux 10 sensor units with 4-pin that must communicate with a single unit with 3 programmable input

I have 10 sensor units, each unit has 4 pin Vcc, Gnd, Digital out and ...
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1answer
60 views

Designing a CANbus+DC power network of sensors

I'm designing a network of sensors to be placed in an outdoor environment, see the attached diagram. The network will consist of 30 data acquisition boards (very low power consumption), divided in 10 ...
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2answers
71 views

Why does the MAX30102 only work on a finger?

I am using a MAX30102 sensor with Sparkfun library for heart rate monitoring. It does work for a finger, but when the sensor is mounted on chest I am not getting a reading. Why is that?
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56 views

Noise level detector circuit design (AC to DC to PWM)

So I'm building a sound level detector. Design requirements are: Only basic circuit elements No IC's, except for op-amps Sound level will be displayed with a blinking LED Blinking LED will be ...
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1answer
67 views

Optical displacement sensor noise and current to voltage conversion

I'm currently involved in a project with the aim of measuring the tremor of mice limbs (displacements of about 100 um). The sensor my group has chosen is TCRT5000 (Vishay), but we are facing several ...
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1answer
52 views

What parameter of this sensor necessary to decide about the required ADC resolution?

From the datasheet of this accelerometer, I need to decide about the adequate ADC resolution. If my reasoning is not wrong the output noise floor of this accelerometer will decide the adequate ADC ...
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29 views

IR Proximity Sensor Not Responding

I'm trying to build an IR proximity sensor using a simple tutorial found online. Here is the schematic and here is the link of the tutorial : https://www.instructables.com/id/IR-Proximity-Sensor-1/ ...
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1answer
29 views

piezo element vs accelerometer

I'm looking at options to detect forces applied to a car door. An accelerometer seems by far like the most popular option, but I was also considering placing several piezo elements inside the car door,...

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