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# Tag Info

6

After purchasing many DS18B20 sensors and probes on ebay I can assure you that price is a useless indicator for quality. Let me address the question in the title of this thread: Which one of these DS18B20 temperature sensors is fake? Fortunately, you can find out for yourself: you cannot proof that a part is authentic but if it behaves differently from an ...

0

Sensor fusion means using the input of multiple (different or similar) sensors to reduce the error compared to using only a single sensor. For MPU-9250, sensor fusion is typically done combining gyroscope, accelerometer and magnetometer data to get to an accurate representation of the orientation of an object in space, rather than its position. Perhaps - ...

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The resistor divider is used for making a reference voltage. When no voltage difference is present between A and B, you get half of Vcc on the analog pin - say 1.65V. When the voltage difference A-B is positive you get more than 1.65V on analog pin, meanwhile when voltage A-B is negative you get less than 1.65V. Between A and B you have to connect a burden ...

0

Indoor lighting usually has a large amount of ripple caused the AC voltage varying lamp brightness at twice the mains frequency. Depending on the particular bulb the variation might be anywhere from 5% to 100%, and could be many times larger than the signal you are trying to detect. A filter attenuates out of band frequencies that could overload the gain ...

2

Hall sensors "sensitivity" can be adjusted by with a flux concentrator / pre saturation which actually changes the magnetic field the sensor encounters. So for example you can use a small neodymium magnet on the backside of your hall sensor. Depending on which way you flip the magnet it will either reduce or increase the hall sensor sensitivity. The ...

1

Most - if not all - Arduino boards have serial connection to a PC, encapsulated in USB. The B in USB stands for Bus, so rather than a daisy-chain, it follows a bus topology. In other words, yes you can connect multiple Arduino's via USB, each of which is addressable from your PC as a serial device (maybe COM ports such as COM3, COM4 ring a bell). But of ...

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Thanks all for your great answers suitable for a variety of situations. In my case, I am trying to use items already on hand. Hence, the ADC with a restricted range. Also, the ADC works from a 5V supply, so originally I did not have a voltage above 10.1 as reference. For future reference, I see that it is dead simple to chose an ADC with an appropriate ...

0

Actually, the animation of the assembly is quite revealing. See the tiny slots on the inner rim of the wheel? The sensing technology is probably optical, just like the scroll wheel in mice and trackballs.

1

A 250 ohm resistor will give you 1~5V which you can low pass filter, clamp, and feed to your ADC. Subtract the 1V off digitally and scale to your engineering units as applicable. The pressure sensor will need a supply of at least 14V with 24VDC being more-or-less standard.

1

It seems that there is nothing wrong with the procedure after all. The problem seems to be that this sensor for some reason, has a high possibility of writing adjacent eeprom memory locations by mistake. Generally the behavior of the eeprom memory when trying to erase it or write it, is far from identical (reading is not problematic). In this particular ...

3

One way to get a low leakage clamp is to employ a BJT emitter-base junction. For example, simulate this circuit – Schematic created using CircuitLab Typical peak current at 4.2V is about 30nA leading to an error of 3uV with a 100 ohm source resistance. It clamps to typically about 5.2V with 12V applied with power dissipation of about 350mW, which ...

2

consider something like this simulate this circuit – Schematic created using CircuitLab

7

Zeners have a very 'soft' characteristic. As you discovered, they start drawing current well before their advertised voltage. The best way to limit overvoltage into an ADC is to use a silicon diode to a fixed voltage. Usually this will be the ADC rail, especially if you put a series resistor between the diode and the ADC to limit any current drawn, but you ...

0

For reasons of power dissipation and voltage load regulation , the most common current shunt chooses the R value to be 50mV at max current. (More or less) Then choose the Pd rating for the resisitor to be 2x pwr of 0.05V*I for 50% reduction of 120’C rise in temp. of the resistor. This is also used in high side current sense IC’s which use analog parts ...

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Yes. There is a trade off between range and precision of measurements in any ADC setup. Since current sensors only give us sensitivity in V/I and we care only about I, sensitivity is inversely related to precision. This also makes sense as more sensitive sensors ought to reflect smaller changes in current.

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I had to call the tech support at mathworks and it turns out that at this point in time the library does not support NI-USB-9162 interface with the NI-9219 which is causing errors in reading data and setting parameters which is a development issue and the team is currently working on a solution and they will contact me if the problem is fixed.

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So you will have a circuit like this, where M1 is your 4-wire device and U2 is 3-wire device: When accessing 3-wire device, you need to send and receive data on the same pin (MOSI). How to achieve this, depends on your MCU. When 3-wire device is sending data, other devices on the bus are not selected, so there's no issue. According to the datasheet of ...

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Step 1) Get a serial terminal program (like realterm) Step 2) Set the device to your RS485 controller Step 3) Set the baud rate (the default for the temp controller is 19200 baud) Step 4) Set the stop bits and parity bits 8, N, 1 (8 bit, no parity, 1 stop) Step 5) EN26Parameter has the same meaning of cycle time for heating action .Parameter ...

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It looks to me like your Y-axis on "the waveform" is kind of ambiguous (what are the units of "Amplitude")? If I look at the numbers on that axis closely, it goes from 0 to 1.65 milli-something. Your MATLAB plot has a Y-axis of labeled "Voltage" and the scale goes from -30 milli-Volts to +30 milli-Volts. The "flat" line may just be an artifact of being "...

4

Expanding my comment into a tentative answer. There is a low power radio transmission system called the "inductive loop" which uses a large loop of wire as an antenna. It provides good signal strength within the loop, and virtually none outside. This allows induction loops to provide radio coverage e.g. within a building such as a concert hall or theatre ...

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The Arduino mega 2650 R3 board has MC33269-5 LDO as power converter if the board is battery powered. If you see its datasheet it can deliver 800mA(Max) current to load if the voltage difference (Vin - Vout) is almost 4V with LDO drop 1.35V. So, as per your question, it can deliver 4W(max) power if the Arduino board is powered by a 9V battery. Now, calculate ...

1

will basically measure the water depth and temperature. My general thinking was to encapsulate the whole thing (except the sensor) in wax to make it water proof. Could I use epoxy instead? What general consensus? Generally you'd use a waterproof housing and then also perhaps encapsulat e the PBA or use a conformal coating. Waterproof housings usually ...

1

Put your electronics inside of the rubber envelope filled with oil. The rubber and oil will keep the water away while transmitting the pressure and temperature to the sensors. The oil could be silicone oil, or mineral oil, as long as it's compatible with the rubber. The rubber could be a finger cut off from a glove. The sensor will be dropped to at ...

0

Well, add me to the long list of people who have wiring issues. I had connected the wires to the Pi on pins 1, 3, 5, and 7, but should have been using 9 instead of 7. The important thing to observe here is that I could successfully i2cdetect the sensor and i2cdump the sensor, but not able to i2cget or i2cset the sensor. Not sure why this is, but the facts ...

1

They come in all varieties, like induction switches, mechanical switches. They are all ridiculously expensive, moreover you need to connect them to a safety PLC or safety relay which are also ridiculously expensive, safety sensor without safety module (PLC, relay,..) has no safety functionality. Instead of using cover safety switches, you can bolt the cover ...

0

As Christian B says in the comments there is no need to use the D2XX driver. You can just stick with the default virtual serial port provided by ftdi_sio and port Adafruit's python code to C or C++. That should be pretty easy with termios. You can, of course, use that same python code as a reference and work with the D2XX driver but unless you are ...

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Yes, this kind of system is called an Inertial Navigation System. https://www.rs-online.com/designspark/what-is-inertial-navigation-for-adasadvanced-driver-assistance-systems-murata-accelerometers The measurement that an INS generates is relative to their last known position, so even after an inertial navigation system has been turned on for several ...

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It's a current transformer with 2000 turns. $N=\dfrac{I_{sec}}{I_{prim}}=\dfrac{100A}{0.05A}=2000$. At least that's what should be, the real situation is that numbers of turns are not exactly 2000, who knows why. Inside a plastic enclosure, there is also a voltage limiting zener diode, so you can unplug the cable without destroying the CT. Normally the CT ...

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From what I've seen from oscilloscope probes (i.e. much more expensive and hopefully accurate and sensitive than the unit you are referring to), these are sensitive to a tens of mA but I wouldn't really trust them below 10 or 20mA, even for units that max out at lower currents let alone 100A. There are, however, very low current level ones that are 1-5A but ...

1

The z axis doesn't have to be specified, because it can determined from the x and y axes. Per MPU6050 data sheet page 21, the axes follow right hand rule, so the z axis points towards you in the photo above.

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It is hard to guess intentions of board maker (maybe not enough space for the silkscreen?), anyway this riddle has a solution. You can figure out the Z axis from X and Y. Check the figure from datasheet. So, looking from top of the board (like your picture represents the board) the Z axis is directed towards the observer and the positive spin goes counter-...

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Solution 1: For simplicity and cost IR sensor + Arduino would be a good sensor. This solution has some cons: you would need a line of sensors, to observe whole line of goal. Also, a pair (IR light emitter and a receiver) needs to occupy left and right pole of goal (or bottom-top lines of the goal). Weakness of this system is here: When ball crosses the goal ...

2

These are some considerations that come to my mind: 1) Rats - they will chew down on any wires they will find tasty enough. Laying down metal shielded cables might be costly and difficult. 2) Range - Ethernet is limited to 100 meters (328 feet). That might be a challenge. 3) Cost - Ethernet might be more expensive than other technologies. 4) Failure - If ...

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