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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2answers
49 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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0answers
25 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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3answers
93 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
122 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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696 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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40 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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6answers
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
34 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
79 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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1answer
73 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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1answer
52 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
44 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
66 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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1answer
70 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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1answer
73 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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914 views

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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2answers
79 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
165 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
199 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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1answer
35 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
137 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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8answers
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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2answers
167 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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1answer
88 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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1answer
217 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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4answers
483 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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1answer
214 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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1answer
202 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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1answer
192 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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1answer
225 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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1answer
99 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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0answers
52 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
543 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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2answers
954 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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2answers
65 views

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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2answers
559 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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2answers
105 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 ...
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1answer
513 views

Turning off op amp for low power application high side or low side

I have a design where I am using a LM324 to act as a buffer (unity gain impedence transformation amplifier) to feed the voltage from several high-impendence voltage dividers into my MCU's ADC pins. ...
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1answer
69 views

Can I use a source follower to read the floating gate voltage then add a fixed tunneling voltage, then feed it back to the tunneling electrode?

So I was reading this research paper: H. Kosaka, T. Shibata, H. Ishii, and T. Ohmi, “An excellent weightupdating-linearity synapse memory cell for self-leaming neuron MOS neural networks,” in IEDM ...
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1answer
127 views

Flyback smps or floating buck converter?

I want to drive a 180V/1A string leds from 220VAC. Which topology should I use: flyback smps (with transformer) or, floating buck step down converter? I know that buck converter will be not ...
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3answers
74 views

ATmega328p TQFP and unconnected pins, what is it the best practice?

I'm designing a board based on ATmega328p in TQFP package. I'm not using all the ports, so, for example, ports from PC0->PC5, ADC6 and ADC7 won't be connected to anything. Can I left them unconnected ...
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1answer
142 views

Oscilloscope differential measurement for battery powered circuit using single probe

I want to measure the voltage across a resistor in my circuit. The circuit is battery powered. I don't want to use the two probe method and calculate A-B to get the results. Can I use one probe to ...
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1answer
105 views

Floating Nwell schematic and introduction in a MOS switch

My classmate told me using a mos (body connect drain)as a switch may have leakage current,because there is a parasitic diode in that MOS,so there will have a leakage current.so i have to connect the ...
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2answers
391 views

floating ground

For a big machine (rope shovel) we put a custom electronics board (gps) in an enclosure. It is connected to the cabinet with Power over ethernet (POE). The POE switch is connected to an isolated power ...
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1answer
257 views

Confusion with calculating the mantissa of a floating point from a binary number

I use this converter to convert a 32-bit binary number to a floating point number. I first find the hexadecimal of the 32-bit binary number and convert to decimal by using the converter. In my case ...
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0answers
94 views

Voltage regulator outputs some voltage even if in shutdown

I've created a dual source energy harvesting board to store energy from small energy sources, like a 3V 15mA solar panel, into a 3F 2.7V supercap and to power a small wireless node (3.3V, 30mA), but I ...
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3answers
825 views

Understanding Common Floating Return [duplicate]

So I'm pretty new to electronics, and I'm getting slightly hung up on the concept of ground. I'm thinking the circuit diagrams below will help me to explain this frustration, because there's not an ...
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2answers
670 views

Getting shocked because of floating ground on psu [closed]

Angus from makersmuse explains here how he got shocked from a printer with floating ground. https://youtu.be/v1OuYg7AJjw I don't really understand his explanation. He basically says that if you ...
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5answers
15k views

Confusion about the meaning of floating

Here they define being floating as: They mention Ungrounded = Floating. But in another forum someone wrote: The signal is consider floating when it does not have the same ground with your ...
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2answers
739 views

How can I return an Arduino digital pin to floating state?

I am trying to setup a programmed reset function for a 3.3V BlueTooth module that resets when its reset pin is pulsed LOW for a short period of time. There is a 47K pull-up resistor in the BT module ...