Questions tagged [floating]

A voltage that is not connected by any conducting path (including resistors) to ground or the key voltage reference point.

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35 views

What is the correct way to bias a floating instrumentation amplifier?

Im designing a voltage measurement circuit that needs to measure differential signals in the order of mV in the presence of high voltage common mode noise. Im using a isolated DC/DC converter that is ...
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71 views

Floating input pin with external pull-up

I would like to improve the performance of my push buttons, which sometimes don't respond when pressed. They have external pull-up resistors and have been initialised as floating input pins. Does not ...
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89 views

Floating analog input of ADS1115

I am using an ADS1115 as an analog to digital converter. R2 and C2 are used as a low pass filter. I have used two schottky diodes as voltage clippers to protect against over voltage. To avoid ...
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55 views

Floating traces on MCU dev boards bad for noise?

When you have development boards for microprocessors with every GPIO pinned out on headers around the edge of the board, is the board more susceptible to picking up noise than a board without all ...
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70 views

How does a pull-down prevent a “false 1” in a pin?

yesterday I asked a question about pull-ups and pull-downs and resistance in an input pin, but I feel that the question that invaded me today is different from my yesterday's post so this is why I'm ...
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106 views

Floating battery negative terminal [closed]

I am building a circuit that uses an op amp comparator stage to control the circuit shown. The op amp circuit will switch on or off the transistor to drive the motor supplied with a set of AAA ...
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60 views

Floating Simulated Inductor

In the image below, I do understand that a grounded inductor can be simulated using op amps. However, to make a floating simulated inductor, I have read some posts that said two ground simulated ...
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1answer
25 views

Floating Nodes Error in Simulation in ORCAD PSPICE

Does anyone have any insight as to what exactly is wrong with my circuit on Orcad/PSPICE? My name is in the project name so I blurred it out for obvious reasons
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17 views

Battery powered device - How to measure external floating differential voltage

I have the following task. As depicted in the sketch, I have a battery powered device which needs to measure the differential voltage VIN between two external nodes, EXT_NODE1 and EXT_NODE2. It is not ...
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1answer
55 views

What is the result of 1 and float on OR gate?

If only one input is 1 into an OR gate, the output is 1, but does that still count if there is no input from other sources? (like float) Or is the output simply float as well?
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130 views

How to get rid of floating voltage on Bridge rectifier

I'm trying to implement a rectifier and AC voltage sensor. The rectifier part works just fine. I'm able to power my device without any issues. Please look at C2 in the screenshot (Circuit schematic)....
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95 views

Why does my ungrounded DC power supply work?

This is a question about electronics theory that I haven't been able to grasp. I was testing a stepper motor wired like the following: https://learn.adafruit.com/adafruit-tb6612-h-bridge-dc-stepper-...
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126 views

Floating Differential measurement?

Can I simply hook up an opamp inputs, (either using a differential or in-amp topology that is/are also powered from a floating power supply), across a device under test that itself has exceeding ...
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71 views

EMC - conducted emissions - unused wires in cable - puzzling coupling

I am trying to understand the impact of unconnected wires in a cable for EMC conducted emissions tests. My product has a shared unshielded cable for supply and communication (I know it's bad practice....
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28 views

Sensing of AC current. Isolation Capacitor Problems?

I want to measure the AC Current flowing through a Piezocrystal (replaced in the circuit with a resistor) being driven by a TI DRV2700. http://www.ti.com/lit/ds/symlink/drv2700.pdf This Chip puts out ...
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141 views

About floating ground and circuit problems

Good morning, I have a power supply with floating ground that drives my circuit. Since the circuit doesn't work as expected (it works fine only if the ground is tied to earth) I did some measures with ...
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6answers
128 views

Is a floating pin equivalent to a very weak pull down?

I know that if a MCU pin is configured as "input" and it is not connected to any pull up/ pull down resistor, it is said to be floating. In this situation, we could say that the pin is in series with ...
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742 views

Why can a MCU input floating pin easily change state?

I would like a technical ("engineering") explanation of why a MCU input floating pin can easily change its state depending on the outside electromagnetic interference. Is it related to the fact that ...
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41 views

How to handle disconnected resistive sensor?

I'm trying to connect a PT100 thermo probe to an Arduino project to measure water temperature. After some research I have found and adopted a design using a Wheatstone bridge and an instrumentation ...
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5k views

Is a pull up/down resistor really necessary?

Logical reading (1 or 0) of a micro-controller input GPIO pin may float if it is neither connected to VCC nor GND; someone said it is because of surrounding RF interference. When a floating GPIO ...
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1answer
49 views

How can I simulate the circuit with floating node in Orcad simulation?

I simulated to test 4n25 optocoupler. 6 pin in 4n25 is base of output transistor. According to google, 6 pin can be not connect pin (NC) because input LED generate the base signal. Orcad ...
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1answer
121 views

555 Timer Output Always V+ or Ground?

If the output of the 555 timer is not trigger to high, is it ground? Or is the output left floating?
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76 views

Floating Power Supplies

Referring to this post, is it possible to float power supplies by simply not connecting the ground wire?
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53 views

Constant Offset Floating Supply

What circuits can be used to provide a voltage supply capable of sinking around 1A of current that will always float 10ish volts below a given supply, that could be from 12 to 200 volts? I have ...
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1answer
47 views

Unused/floating pins on BTS5016

I plan to use Infineons PROFET BTS5016 in a coming project. https://www.infineon.com/dgdl/Infineon-BTS5016-2EKA-DS-v01_00-EN.pdf?fileId=5546d4625a888733015aa41a5e161129 I will not use the ...
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1answer
67 views

Floating analog input value

To use my sensor I need to supply 24V. So I converted 4.5 V from battery pack to 24V and converted it again to 0-1.66V using a voltage divider. So far I can read the output of the sensor using the ...
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73 views

Micron NOR unused pins have pull-ups. Any danger just leaving them there?

I have a board designed for a dual-die Micron MT25QL512 QSPI NOR flash. These parts are in short supply, but the board fabricator had some single-die MT25QL128, and used them instead. The single-die ...
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77 views

Measuring small currents at DC high voltages without floating meter

I'm doing a project with a Cockcroft-Walton multiplier that will output up to 40 kV DC at up to 10 mA. The the circuit takes an input of 10 kV AC at 60 mA and 60 Hz (from a neon sign transformer) and ...
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How can I float a pin that otherwise should be low?

I want to enable/disable a TI TPS54302 buck regulator with a microcontroller. The enable (EN) pin should float to enable the device, or be tied low to disable it. I currently have the EN pin ...
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115 views

Consequences of leaving unused inputs of clock buffer floating. Alternative: best practice

I'm using a Si53342-B-GM Original datasheet download at silabs for the si5334x-series as a clock buffer. In some cases I only need to distribute a single clock signal and in some of my cases I ...
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3answers
259 views

Why does a pull down resistor eliminate floating input

Ever since I connected a button to an Arduino for the first time, I've wondered how does the resistor prevent floating input from happening? I've read several answers to similar questions, seen videos ...
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1answer
467 views

Floating input in Op-amp Readout Circuit?

I was analyzing this circuit diagram in a thesis about a capacitive EEG electrode. The author talks about a flaw in the design where there is a "floating analogue input" that is causing the op-amp to ...
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39 views

Isolated power supply with output on a 2kVDC floating ground

I am building a system of detectors which are referenced to independent floating grounds. The maximum voltage between each stage is 2kVDC. So I need isolated supplies which can operate continuously at ...
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1answer
167 views

Floating neutral in TN-S or TN-C-S earthing system

Since neutral is bonded to ground at building distribution point in a TN-S or TN-C-S earthing system, could floating neutral happen under the following conditions: Loss of N and/or PE at transformer ...
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5k views

What is the right way to float a home lab?

I just got myself some new toys for my lab at home like 30V DC power supply, KKmoon signal generator and a Rigol DS1052E. I want to float everything, because I don't want to spend any money on stuff ...
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229 views

Is it possible to get a floating power supply to power multiple MOSFETs

Hey guys this is my first post on stack exchange so please go easy on me! I have a hobby project where I was trying to make a few batteries go in series using a micro controller and a floating power ...
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122 views

Can I leave it unconnected pins in the level shifter?

My concern is that pins are connected between DB25 and TXS0108E, but are not connected between TXS0108E and the Header 5x2. There is only the tracks between TXS0108 and the Header 5x2, but there is no ...
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416 views

Floating DC power supply (solar panels) - do I need double-pole breakers and why?

I am in the process of building a small off-grid solar setup. There will be 4 parallel strings of panels in this setup, and I understand that for 3 or more strings, you need some sort of over-current ...
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745 views

Floating Source Voltage Difference to Earth

I was reading about floating voltage on web but there is something that I couldn't understand. I attached photo of circuit. As you see it shows 60v difference between neutral of flating source and ...
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324 views

Can I leave the input pins of an ADC channel in floating state?

I'm using this 4-channel ADC: MCP3422 -> Datasheet I only need to use 3 of the available 4 input channels in total. Normally I would add footprints for pulldown resistors for example in case a ...
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348 views

How do actively driven mosfets or transistors react to floating source?

Attempting to add some lights to a car's "intelligent" lighting system. Want to make sure I understand how my n-channel mosfets will react to losing their ground, while their gates are still connected....
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216 views

Floating analog input using Arduino with 1m cable

I use an analog input from an Arduino to read the value from a piezo plugged in parallel with a 1M ohm resistor. I followed this tutorial from Arduino: https://www.arduino.cc/en/Tutorial/Knock Here ...
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291 views

Trying to understand floating voltage

I'm trying to understand the concept of a floated voltage, and why it is needed in some cases. For my own case, I am using a variac connected to a rectifier to provide a DC voltage for a circuit, (...
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159 views

What does floating source mean in this context?

What makes the load in the below circuit floating?: Does that mean the load does not have a ground shared with the circuit ground?
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57 views

Preventing the voltage between two isolated grounds from exceeding max rating

Consider the low-side current sensing application shown in Figure 1. Grounds 1 and 2 are galvanically isolated. Assume, for example, ground 1 is the NEUTRAL line on mains power (\$V_g\$), and ground 2 ...
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2answers
762 views

Grounding a Laptop

I have the following problem: I am currently debugging an electronic sensor board which is connected to the USB port of a laptop. The USB port is used both for communication via UART and to supply ...
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1k views

Disconnecting ATX PSU's ground from mains earth to protect my oscilloscope

Like many I took an ATX PSU, hooked green to black, and have a nice PSU. I am experimenting with a HP oscilloscope from 1997 and as you know, those are grounded to main's earth, just like my ATX PSU. ...
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Measuring floating gate potential with minimal leakage current

I am working on a sensing device where the voltage of a floating node is dependent on the quantity to be sensed, as well as the net charge stored in the node. I would like the device to be only ...
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734 views

Current source with grounded Load and floating power supply

The following circuit represents a basic op-amp current source and can be found in the "Art of electronics 3rd edition" in page 228. \$ I_{load} \$ is easy to calculate in this situation. The ...
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135 views

Why is this capacitive circuit not working in both multisim and LTspice

The voltage at the top most node of this circuit should be the average of the input voltages. Vtop*CT = C1*V1 +C2*V2 +C3*V3 where CT = C1+C2+C3 I get 0V instead. UPDATE Thanks for the help. I ...