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

"Best practice" and "inexpensive" are both subject to opinion. In all cases, I'd put a really inexpensive little processor at the sensor, and have it talk digital. The 1950-1975 way to do it would ...
TimWescott's user avatar
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Best practice in transmitting sensor analog signal over longer distances (approx. 100') -- in cost sensitive products for microcontrollers

The other solution can be I2C — there are extenders, allowing to create buses up to 100m (300ft). One of them is NXP P82B96. It is very useful in amateur constructions, because it is not expensive and ...
VillageTech's user avatar
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7 votes

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

I've had excellent results transmitting sensor data using the Controller Area Network (CAN). I have a 16-bit microcontroller with a built-in CAN that interfaces through SPI to a 24-bit A/D converter. ...
Paul's user avatar
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6 votes

AC/DC power supply module with 20mA output current

I am powering medical tool so output current must be max 20 mA because sometimes the patient have to touch so If i wamt (sic) to be safe it must be max 20mA. No, for medical devices you don't use ...
Transistor's user avatar
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5 votes

Need more current than 4 mA in 4/20mA loop current

You can increase the voltage drop and use a (very efficient) DC-DC converter to convert the higher voltage drop to a higher current. For example, if you need 3V at 20mA (60mW) you could drop 17V or so ...
Spehro Pefhany's user avatar
5 votes

How do 4-20 mA receivers work?

They are many loop powered sensors, so it is possible that you may need only 2 wires to the sensor. You have not included details to your sensor so it's hard to know what you have. Providing the ...
Jack Creasey's user avatar
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5 votes

how to get 4-20mA output

While the other answers address the inappropriate choice of op-amp, there is another significant problem. instead of n-MOSFET i use CL100 transistor and for p-MOSFET i use CK100 You can't just ...
jms's user avatar
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5 votes

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

I share your reluctance to put a whole CPU per sensor, however ... RS-485 for Cost-Sensitive Sensor/Output Communications I can recommend the following, which is how I now do these kinds of sensor/...
jonathanjo's user avatar
5 votes
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How does a 4-20mA bus powered sensor work?

A two-wire 4-20mA transmitter has its own voltage regulator to be able to handle high loop voltages, uses less than 4 mA for its own operation, and has a circuit to adjust the additional current that ...
CL.'s user avatar
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4 votes
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4-20mA Current Loop - Multiple Sensors

The best way to understand this is to look at wiring diagrams from actual vendors. For instance, Acromag has such a diagram, if you look here p7/8 you will see that your 2 loop transmitter can share ...
Auberon Vacher's user avatar
4 votes
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How do 4-20 mA receivers work?

Despite the title, your inquiry seems to apply more to the transmitter design. The receiver, after all, can just be a 250 ohm (or whatever) resistor connected to ground. The other wire would be ...
Spehro Pefhany's user avatar
4 votes

how to get 4-20mA output

You substituted an inadequate op-amp- at 4mA the common mode voltage is within 1V of the positive rail. Either use a better (and much more expensive) op-amp or redesign the circuit to work with an ...
Spehro Pefhany's user avatar
4 votes

Conversion 0-20mA to 0-5V

simulate this circuit – Schematic created using CircuitLab Figure 1. A 0 to 20 mA to 0 to 5 V conversion can be done with a single resistor.
Transistor's user avatar
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Is a current varying output or voltage varying output for a 4-20 mA sensor more reliable for a rocket?

As far as signal integrity, 4-20mA is almost always better. Two reasons why: Noise is usually less of an issue. Circuit discontinuity is instantly detected. As for its use in high g applications, ...
MadHatter's user avatar
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4 votes

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

4-20mA loop will require some complex drive electronics and a higher supply voltage (the drive amplifiers ive used before were 18V). While it is still commonly used in industrial systems to this day ...
cstanto's user avatar
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4 votes

4-20 mA to 0-3.3V converter

This circuit is wrong. It's intended to be a differential amplifier using a current sense resistor, but the op amp is drawn with positive feedback instead of negative. Swap the inverting and ...
Hearth's user avatar
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4 votes

4-20 mA to 0-3.3V converter

This doesn't answer what you are asking but may solve the problem. simulate this circuit – Schematic created using CircuitLab Figure 1. A current to voltage converter - also known as a ...
Transistor's user avatar
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4 votes
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Converting a 4-20mA 24V signal to 0-5V?

The simplest way is to use a 250 ohm resistor and remove the offset digitally. To get an isolated input might be done by creating an isolated supply and digitizing the signal, then transferring it ...
Spehro Pefhany's user avatar
4 votes
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4-20 mA to voltage converter: What is the significance of the 12 V power supply to Schottky diode D2 and D3

The idea is that if a voltage less than 0V is applied to the input then D3 will conduct and (assuming some source resistance) keep the voltage at the non-inverting input from going so negative that a ...
Spehro Pefhany's user avatar
3 votes
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4-20 mA loop powered ADC with display

For a loop-powered 4/20 mA device, 4 mA is the absolute maximum current your device should need to operate correctly (ideally 2 mA max). That’s your first hurdle. Based on this, it sounds to me like ...
Andy aka's user avatar
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3 votes

how to get 4-20mA output

The LT1490A is specified as being: - Rail-to-Rail Input and Output The LM358 will not want its inputs to get as high as the circuit design expects. With 4 mA ...
Andy aka's user avatar
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3 votes
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Issue having 4-20 mA interface with ADS1115

It looks like it will function. Whether it's "reliable" or not depends on the environment. It's not up to "professional" process control standards. You should consider an anti-aliasing filter- ...
Spehro Pefhany's user avatar
3 votes

XTR111 4-20mA to 0-10V issue

Figure 1. From the datasheet. The CDSOD323-T05C appears to be working perfectly. You need the T12 or T12C.
Transistor's user avatar
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3 votes
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Controlling a 0-20mA transmitter from an isolated PWM signal

Add a CMOS logic gate after the optocoupler/R2. That will buffer the output and the voltage will be more accurate and the time constant will be the same for on vs. off. split R4+R3 approximately ...
Spehro Pefhany's user avatar
3 votes

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

If you are looking to keep it simple and not convert to digital format then current sensing is a cheap and practical way to go. This does not have to be a 4-20mA system. You are free to choose the ...
Gwyn's user avatar
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3 votes

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

If you have a suitable micro at each end, and your micro can handle the processing required, Ethernet is a very good solution for long-distance comms. Cat5 Ethernet cables are available in almost any ...
Graham's user avatar
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3 votes

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

I like TimWescott's answer the best, but another option is to look at a professional microphone for live sound and studio work. They often run hundreds of feet through noisy lighting and AC power ...
AaronD's user avatar
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3 votes

4-20mA to switching output

You can make a BJT turn on at a relatively well-defined current through a base-emitter resistor. Let's say you choose a 12 mA (halfway between 4 and 20) threshold. We want about 700 mV at that ...
Neil_UK's user avatar
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3 votes
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pt100 RTD transmitters not working - two in a row - am I doing something wrong?

32mA is typical of what a transmitter will output with an open sensor. Connect a 100 ohm resistor directly across the terminals A to B and short B to B' and measure the current (preferably with a ...
Spehro Pefhany's user avatar
3 votes
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How can I create feedback measurement with an operational amplifier? 0-20mA measurement

If your load resistor Rload can be "floated" so that neither end is grounded, the circuit becomes very simple. As you say, a current-sense resistor (120 ohm) is used to sample transistor ...
glen_geek's user avatar
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