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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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Why is this boost converter bypassed?

In my project, the input power of a device comes from a battery pack. Here it is: Here is a simplified architecture inside the battery pack: There is a charger that charges the battery when V_IN is ...
uz3il's user avatar
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1 answer
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Level shifter (floating shifting ?)

I'm currently studying level shifters, and I have a question: Is it possible to design a level shifter that translates 0 and 5 volts to VSS (e.g., VSS = 5V) and VDD (e.g., VDD = 8V)? If so, could you ...
Nedou's user avatar
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2 answers
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Understanding safety concerns with RGB modding hot-chassis TV

I'm in the US. I'd like clarifications on the safety of RGB modding an old, hot-chassis TV. I know it's not economically viable but I'd like to learn. While researching how to do this safely I ...
lwiseman's user avatar
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4 votes
3 answers
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Unused inputs and out puts on 74 series ttl logic chips

Hi I am using a 74ls38 quad 2 input nand buffer with open collector outputs and as well as a 74ls74 Dual Positive-Edge-Triggered D Flip-Flops with Preset, Clear and Complementary Outputs. On the nand ...
Curggles's user avatar
2 votes
5 answers
343 views

What is the correct definition of a floating output DC-DC converter?

This is what Dave Tweed wrote in his post here about a floating power supply: It simply means that the output side of the power supply is completely isolated from the input side, not even sharing a ...
hana's user avatar
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1 answer
52 views

Floating output voltage in USB chargers?

A USB charger is usually galvanically isolated from mains for safety reasons. If I touch the output connector while standing on the ground (i am at earth potential), will I get a shock? I think yes, ...
user2276094's user avatar
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1 answer
50 views

Does the current have any significance at float charge?

I'm considering using a 4V 1Ah lead acid battery to power my embedded system project. I want to charge this battery at its float charge voltage. Does the current have any significance at the float ...
A. Vehbi's user avatar
1 vote
1 answer
57 views

Will this electric guitar wiring scheme be noisy?

I want to wire my guitar using two SPDT switches for my pickup selector. This is so I can have four sounds: lower, upper, both in parallel, both in series. I'm concerned that when it's set to use ...
neenscrame's user avatar
1 vote
1 answer
88 views

Floating node of amplifier in LTSpice

I have been trying to create an actively loaded degenerated CS amplifier with current mirror in LTSpice and whilst working on other aspects of the amplifier the Vout node decided it was floating. I'm ...
EEE22's user avatar
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1 vote
1 answer
72 views

Earthing: TN in TT installation?

Something odd happened at work today: the whole building installation is TT, just like the whole country. L1-L2-L3 supplied to the transformer and then L1-L2-L3-N goes to the loads. I noticed that we ...
scan's user avatar
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1 vote
1 answer
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Can I use battery in a high voltage (600V) float circuit?

I know this requirement is weird, but it's indeed what I need in my circuit. A 12V acid battery powers my circuit board and connects to the signal-VCC and signal-GND. The circuit works at high ...
Robert Liang's user avatar
5 votes
3 answers
2k views

Why have floating outputs on a power supply?

I saw a post some time ago where the person made a power supply which has what he called floating outputs. What are the floating outputs of a power supply and why would you need floating outputs?
JoeyB's user avatar
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1 vote
2 answers
210 views

Input common mode voltage in differential amplifier used for high-side current sensing

I am confused about the input common mode voltage seen by an op amp configured as a differential amplifier for high side current sensing. Assuming that the op-amp and the load for sensing share the ...
Jackson's user avatar
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3 votes
4 answers
2k views

Alternative to MOSFET transistors as a switch

I am looking for a 3-legged component that can be used as a switch as an alternative to an NMOS transistor. My circuit currently looks the following: - simulate this circuit – Schematic created ...
Carl's user avatar
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I am driving a LT3092 current source with a variable voltage - to get a variable DC current, but the output needs to float 0 to 1.5V above ground

What type of buffer amplifier would work - either discrete opamps or a differential output opamp? The output voltage would ideally vary up to 12VDC. The variable current source has a variable load ...
Charlie Landino's user avatar
1 vote
1 answer
95 views

What is the safest and most noise free grounding method floating or non-floating for audio plugs & circuits on 2U aluminum case and SMPS

I have read countless documents and viewed schematics on this subject but am still confused when it comes to physically building a box and running all of the wires correctly and safely. I drew a very ...
Jim Dandy BOA's user avatar
-2 votes
3 answers
109 views

Why is the voltage across the 30 kohm resistor taken as 6 V? Is it something to do with the fact that it is a floating voltage source?

Why is the voltage across the 30 kΩ resistor taken as 6 V? Is it something to do with the fact that it is a floating voltage source?
Amruth Parakkunnath's user avatar
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1 answer
88 views

Circuit that holds a PIN to GND and leave it floating after power on

I need a simple circuit that during power on fixes a pin of an IC to GND and after a while leaves this pin floating. Another circuit should be the same, but fixing another pin to -VEE (-30 V) and then ...
mtx4's user avatar
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0 votes
2 answers
589 views

What issues can floating nodes cause?

I recently asked a question on why my naive implementation of a XOR circuit in CMOS was wrong. One of the most mentioned issues was that I had a floating node in my diagram. I've looked up floating ...
Connor's user avatar
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1 answer
143 views

MCU floating pins

You'll have to excuse my ignorance I'm learning as I go along. I would like to use a switch to toggle the state of the ESP32_EN pin in the schematic from high to low, however the pin can not be left &...
Paul's user avatar
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5 votes
2 answers
201 views

Coupling floating differential inputs to an amplifier with/without resistor pair

My question is about wiring a "floating differential input" signal to an instrumentation amplifier. I've read that in the case of a floating signal two high value resistors are used to ...
ty_1917's user avatar
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1 vote
1 answer
203 views

Mains: If I measure 30 VAC on a switched-off circuit, is it more likely that one wire is floating or "partly energized"?

It's a 3-way switch circuit powering an LED light bulb. I don't know how possible it is for a wire to be partly-hot at some level between 0 and 110 V. I know that floating voltages show up as ...
Vulcan's user avatar
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2 votes
2 answers
690 views

How do floating voltages actually work?

First of all, I do not have any electrical / electronics background, I am just a self-taught, so there are very high chances that this question does not make any sense at all. Sorry in advance if that ...
Carlos Garcia's user avatar
1 vote
1 answer
81 views

Texas Instrument OPA192

I'm examining the datasheet of the OPA192. When the inverting input of op amp tied up the op amp output and if the non-inverting input of op amp had been floating, what would have happened the op amp ...
bcdyzi's user avatar
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0 votes
2 answers
202 views

Why does this active-low relay work when floating?

I have the following circuit: simulate this circuit – Schematic created using CircuitLab When I digitalWrite(HIGH) the GPIO pin, the transistor closes and ...
Anonymous Guy's user avatar
2 votes
1 answer
198 views

Which consumes less current in microcontrollers: Always HIGH pins or always LOW pins?

I am driving a P-MOSFET (IRLML6402) with ATtiny24A microcontroller. This is a battery powered system; that's why ATtiny is always on sleep. I originally configured a BJT which is driven by the ...
CaveScientist's user avatar
0 votes
1 answer
229 views

Capacitor to earth in floating power supplies

I'm looking at using two separate, floating supplies in a 20W power amplifier design to generate +24V, 0V, and -24V low-impedance rails. Some research suggests this is doable, and seems much less ...
JAE's user avatar
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2 votes
2 answers
300 views

ESD damage without earth ground

Can you explain how a totally floating PCBA (with semiconductor chips/ components stuffed, but no any connection to earth GND) is damaged by an ESD event from human touch? If human body is charged to ...
user315429's user avatar
3 votes
2 answers
474 views

How to drive multiple floating N-channel MOSFETs

I want drive a RGBW-LED (CREE XLamp XM-L) using a synchronous constant current buck. To control the brightness and color, the LED of each color channel is controlled by a shunt transistor using PWM. ...
Michael's user avatar
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1 answer
279 views

Microchip FPGA Internal Short Circuit

We are using the FPGA ProASIC3E A3PE1500-PQ208. The FPGA got internally short circuited during runtime. The FPGA IO Supply Voltage and FPGA ground are permanently short circuited and it is not ...
abunickabhi's user avatar
1 vote
1 answer
45 views

Vl53l0x ToF Sensor turn on without gnd

My ToF sensor turn on if I not connected its ground pin to common ground (I let it float). Why?
DJDB999's user avatar
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7 votes
3 answers
1k views

Tying open-collector outputs to TTL inputs

I know that open collector outputs are effectively either 0 V or high-Z. I also know that TTL chips tend to read a disconnected output as high, but that really you should have something like a 1 kΩ ...
Rob Simmons's user avatar
1 vote
0 answers
89 views

Why is the voltage across high impedance indeterminate?

The analog pins on my Arduino read sporadic values when unconnected, and my multimeter (set to VDC) shows random values when there's no connection between the probes. If I connect the analog pins on ...
glibg10b's user avatar
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-3 votes
3 answers
214 views

Do disconnected input pins act as “antennas” capacitors that get gradually charged, building up higher and higher voltage?

Disconnected input pin acts as an antenna affected by surrounding electromagnetic noise, and can "float" between on and off. Does the input pin also act as a capacitor that gets gradually ...
LearningBasicComputerScience's user avatar
0 votes
4 answers
480 views

Are there logic gates by which a signal could propagate backwards?

Is there a type of logic gate with floating inputs (I'm using that term loosely) such that a fixed voltage on an output could "propagate backwards?" Let me clarify with examples... Say you ...
mattroos's user avatar
6 votes
2 answers
713 views

Counting signal switching between floating and LOW in Arduino

I have a rotating contact (contact breaker of an ICE) that switches between being not connected to anything (floating) and being connected to the case of the ICE. The engine case is connected to ...
Yanick Salzmann's user avatar
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0 answers
77 views

Bias tee for floating DC supply

I have a floating DC low noise current source driving a load. I also need to drive this load with an RF source but the grounds are not referenced to each other so I don't think I can use a standard ...
jamie1989's user avatar
  • 101
0 votes
0 answers
218 views

Connecting GND on secondary side to protective ground

We have a battery powered equipment which mainly consists of a temperature sensor connected to a microcontroller via a filter. In addition to battery power we have now added the possibility to use a ...
user285846's user avatar
1 vote
4 answers
1k views

Is it possible to "stack" the outputs of 2 or more buck converters?

Is it possible to "stack" the outputs of 2 or more buck converters? The buck converter circuit in question I am considering is the 48v to 5v typical example circuit from page 20 of the ...
Josh Nabours's user avatar
2 votes
0 answers
114 views

Randomly Floating PWM signal

I am having trouble with a randomly floating digital signal. Transmission is between a microprocessor and a CPLD unit and is used to run a half bridge. Measurement was taken after the output resistor ...
Julez's user avatar
  • 21
1 vote
2 answers
307 views

Random activation of transistor base by capacitive coupling (ghost voltage)

I have a smart module used for home automation. It is equipped with two relays, a wifi mcu, and two switch input. For the switch input it uses AC mains detection using transistor (non-isolated.) In ...
nour mehdi's user avatar
1 vote
1 answer
283 views

What does "Default Output State" mean for a digital isolator?

I do not understand the term "Default Output State" of the SI8422AB-D-IS digital isolator. I saw it on this datasheet at page 3: Does it mean "the default output voltage if the input ...
Christianidis Vasilis's user avatar
-1 votes
3 answers
992 views

Why does an LED remain glowing when MOSFET gate is open?

Hello, I'm working with an N-Channel MOSFET (Link to data sheet for the MOSFET - https://www.onsemi.com/pub/Collateral/FQU13N10L-D.pdf) for the first time on a DC motor project, and I'm trying to ...
Dale's user avatar
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1 vote
3 answers
453 views

Floating voltages and current path between isolated circuits

I have a bit of trouble understanding floating voltages. I thought about quite a few circuits and scenarios involving isolation transformers and floating voltages but something is still off. Here are ...
sergiu reznicencu's user avatar
3 votes
1 answer
224 views

Strange floating base NPN behavior

I'm learning about NPN transistors and have wired up this: I understand some of its behavior, but one is a complete mystery for me. First, if I tie "B" (green dangling wire) to "G"...
klao's user avatar
  • 31
2 votes
2 answers
1k views

Dc power supply outputting sine wave at both terminals

I connected a DC power supply (set to 706mV) to a 1kohm resistor as this: The semantic is like: However, strange things happen when I use the oscilloscope to view the voltage waveform at point A and ...
gudako's user avatar
  • 183
5 votes
4 answers
1k views

Confused about opamp's inner "ground"

(well. I am NOT speaking of "virtual ground" throughout this question/) As this figure has shown an opamp can be viewed as: We all know that an opamp like this has two inputs and one output ...
gudako's user avatar
  • 183
0 votes
1 answer
109 views

No unconnected inputs yet ICs (logic gates) still seem to yield erratic/odd behaviour

I just finished building a 4-bit adder on a breadboard and I am experiencing some quite odd/erratic behaviour and I am wondering why. The actual circuit/logic works as intended, meaning the 4-bit ...
NoName123's user avatar
  • 265
3 votes
3 answers
664 views

Understanding Differential Mode Voltage of a Floating Circuit?

I am currently trying to work on studying for the ECE NCEE FE exam, but I came across the problem and don't quite understand the answer. Essentially we have an ideal transformer with an arbitrary ...
ReThink's user avatar
  • 39
0 votes
0 answers
285 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 ...
lreyes's user avatar
  • 1