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16

By default, the internal ADC of an Arduino / ATMega MCU uses the supply voltage as a reference. When you switch on a LED, more supply current is consumed and if your supply has some series resistance it could decrease a little bit in value. Possible solutions are: use the internal voltage reference for the ADC. make sure that the current through the LEDs ...


6

It should (typically) work to have ~410mV out at room temperature. So I suspect an error in the wiring or an incorrect or damaged part. Note carefully however that the OA1 is called upon to sink Vdiff/5K, so for 3V out it will have to sink about 62uA with an output voltage of about -160mV. Obviously, it won't do that with a single +5V supply. In fact, it ...


6

If the sampling rate of these sensors is reliable enough, I could just record the initial timestamp and the sampling rate and assume uniform sampling I spent 30 seconds looking at the datasheet (Ctrl-F "Frequency") and, well, it doesn't have an onboard crystal oscillator, so the internal clock is pretty inaccurate, and it will drift. Therefore, ...


6

That is an analog sensor with an output of 10mV/°C so a change in ground potential will have an effect on the ADC reading of the sensor. Make sure the GND common for the LEDs in your present circuit is run back to the power supply and not through the Arduino or any part of the sensor signal path. You could also consider adding external drivers for the LEDs, ...


6

An arduino uno is not the most noise free board for analog signals. The arduino does not separate or filter the analog section of the atmega microcontroller from the digital side. Depending on what you are doing, pwm, dirty input voltage, high current via a pin causing voltage droop or rise, etc your analog readings are going to vary. A proper board for ...


4

In response to David Mikeska's answer, and I do so because it's too long for a comment: I would think you would need to transpose your Wheatstone bridge's offset voltage across a resistance to induce a current across this resistance to produce the input signal. Sorry, but that makes no sense at all. The two measurement points are both voltages, produced by ...


4

What is the output voltage of the first two opamps and the voltage at the inputs of the finals stage? With only a 5V supply it is easy for the intermediate stages to exceed their output range or common mode input range. Are you actually using LM324 devices? The maximum output is only about 3.5V with the minimum about 0.7V if required to deliver any signicant ...


2

You'll need a linear current to voltage converter. simulate this circuit – Schematic created using CircuitLab Figure 1. Full schematic of a linear current to voltage converter. If the ADC is 0 to 5 V then set R1 to 250 Ω. Your 4 - 20 mA will give an input of 1 to 5 V so you'll lose 20% of your useful range but this is a small price for the simplicity. ...


2

A pretty standard fluid level sensor (optical, capacitive, ultrasonic, IR) will mount to a fixed point and look down at the fluid. If you must have the sensor float, consider measuring distance to some fixed point above the water (since your floating platform will be on the water, it is at water level). Laser rangefinders should work, although depending on ...


2

why ±10V is a common voltage range for commercial DAQ cards It probably stems back from analogue op-amp circuits being powered from ±15 volt power sources. 10 volts peak would be a pretty normal undistorted or unclipped signal that could be produced from an op-amp on this power rail. I think that using 10V instead of 1V on the output of the external sensor ...


2

I think it's worth answering with some form of reassurance that the circuit (as shown) should operate as expected. Here's a simulation using micro-cap 12: - So, given that the OP reports the output to be greater than 3 volts, it's highly likely that the problem is an implementation issue (faulty op-amp, wrong value resistor, bad connection, wrong connection,...


2

There's a somewhat more informative section in the Äkta Avant User Manual. Your E9 module is an accessory for the Avant. From page 147: If you leave a digital input unconnected, it will read as a digital high (logical level 1.) You have to intentionally pull it to ground to make it read a digital low (logical level 0.)


1

Figure 1. The digital input 9-pin pinout. You don't have to worry here. Your only option is to connect any of the digital inputs to signal ground. This can be done with a mechanical switch, an NPN transistor or a 5 V logic signal. You can assume that there is an internal pull-up resistor to keep the line high if unconnected. I do not understand the "...


1

Detection of a passive external switch must have internal pullup selected, added or automatically included by design in the datasheet specifications. Make no assumptions if uncertain! Measure Voc open circuit input voltage and Isc current to 0V. Also, check for ESD protection. added You did not include the detail "Closed Circuit = 0" in your ...


1

The output stage of the LM35 is famous for being a little moody… in my experience it often tends to oscillate, if the signal line is longer than 5-10cm (typical if externally mounted). Also it is somewhat weak, as you already noted. Look with a scope at the output signal, if you see a sawtooth the LM35 is oscillating because of the excessive capacitive load (...


1

Because an inductive sensor is affected by all localized ferrous material in the vicinity of the probe face, when there isn't a missing tooth the relative peak-to-peak change in permeability as the teeth are passing is actually less then when there is a missing tooth passing by. The missing tooth inevitably generates a higher p-p voltage signal because the p-...


1

With great help from DKNguyen I will use two relays in series with the motion sensors: simulate this circuit – Schematic created using CircuitLab Thus each sensor trips its own relay. If both relays are switched to on, then the - signal can go through to the lights.


1

No, that is not correct. The datasheet specifically explains that READ ROM command can only be used with a single device on bus. But with a single device on bus, you don't even have to use the ROM address. When there are multiple devices on bus, you must go through the identification process to figure out which ROM IDs there are on the bus, and then each ...


1

You can't simply OR the two bytes together. First byte contains the low byte and the next byte contains the following byte contains the high byte of a 16-bit result. You need to shift or multiply the high byte to correct value to concatenate the two bytes into a 16-bit value. Basically what it means is that if you have a little-endian MCU, you could simply ...


1

Yes, it's needed, usually you don't want to argue with datasheet suggestions, they are there to make the device perform according to what is promised. These devices consume current in gulps based on clock they operate at, and any wiring you add will make voltage noise higher at the chips unless capacitors are used. Besides, Raspberry Pi has a switch mode ...


1

I think you find it hard to locate a more reasonable device than this: - So, don't be fooled by the name: -


1

As Mattman944 has mentioned in a comment, this design will not trigger until the smoke is very dense. The efficiency of LEDs and phototransistors will vary from batch to batch. So it's not possible to design a circuit with fixed resistors that will work reliably. So you will need to adjust the two variable resistors P1 and P2 up or down so that the alarm ...


1

Depends how big the jumps are. Your sensor outputs a signal which changes by 10mV per °C. The Arduino Uno really isn't great at measuring small changes like these. It has a 10-bit analog-to-digital converter, which means it can measure 2^10 = 1024 different voltage levels. Over a range of 0V to 5V this gives you a resolution of about 4.9 mV (5V / 1024), ...


1

Here's an inductive sensor with a claimed sensing distance up to 20cm: https://www.seeedstudio.com/Grove-2-Channel-Inductive-Sensor-LDC1612.html It uses the TI LDC1612 chip. MORE inductive finds: https://www.htmsensors.com/inductive-proximity-sensors/metalhead-all-metal-sensing-with-io-link/ https://www.automationdirect.com/adc/overview/catalog/sensors_-z-...


1

There are a number of sensors aimed at air quality monitoring, such as Sharp's GP2Y1010AU0F with an analogue output depending on the smoke density, or fancier units such as the Sensiron's SPS30 that has internal algorithms to give counts for different particle sizes. The problem you have with both of these is that they are intended for air quality ...


1

So I want to generate a brief signal "Analog In" 24V for my GPS/Modem ... I think you want a digital on-off for this, not analog. ... signal ... when the elevator arm moves UP and passes contacless sensor A first, then contactless sensor B. No signal when it moves down past B and then past A. When the arm moves down again past B first and then ...


1

I would think using an FFT or Spectral Density Analyzer is the most common way to measure noise to determine the amplitude and see if it is Gaussian or filtered Gaussian (Brown or Pink or White noise for example) or if there is a DC component... The filtering to obtain maximum SNR ought to be matched to pass the spectral density of the signal and inversely ...


1

This should clarify your doubts. As you know, we will only conduct current when there's a straight path to ground. Therefore, during your off/sleep scenarios you should check what the voltage levels should be.


1

As mentioned there isnt an open-source standard due to the time-cost benefits plus licensing if you want to sell your product. The easiest way is buying the stack which if I remember correctly is over 5000 USD, the benefit is you get technical support. Anyways just as a proof of concept I developed a hardcoded IO-Link stack, in case its of use to anyone: ...


1

First of all capacitive sensing doesn't rely on anything about body resistance. It works even with insulation in between. In fact, with glass it works better given it's dielectric properties (there is an appnote for the FDC converters working thru 10mm of glass, for example). That aside we are reasonably grounded (on the order of kiloohms), otherwise people ...


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