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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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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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32 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
142 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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47 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
64 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
40 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
67 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
50 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
57 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
33 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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146 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
91 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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60 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
519 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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0answers
113 views

Linear mosfet driver floating supply

I've been trying to find ways to drive an N-Channel MOSFET gate higher than the power rail in order to make use of the full supply available. The MOSFET needs to operate in the linear region using an ...
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2answers
330 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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Switch mode power supplies: Floating outputs, ground loops and audio

Since we'll be talking about mains voltages, I'll preface this by saying I'm in the UK, so we have a 240V mains voltage. I built a guitar effects pedal the other day, and promptly fried a friend's ...
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4answers
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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
306 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 ...
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1answer
349 views

why trace_printf(“%f”,x); triggers a HARD FAULT on a stm32 MCU?

I'm using a stm32 F413ZH microncontroller with HAL libraries (mainly written to be used with c but can also be used with c++) in eclipse, actually I managed to completely configure eclipse including ...
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124 views

Can I leave bootstrap pins floating? (Internal pull-up)

I have a microcontroller that uses 4 GPIO pins as "bootstrap pins". The state of these pins (high/low) at boot time will determine important features of the microcontroller, such as output voltage to ...
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1answer
72 views

HSPCIE Default Value for Float Nodes

I have M inputs. I want to connect m of them to Vdd and leave other nodes floating. I know that in real experiments the floating nodes can get any value between 0 and Vdd. I was wondering how HSPICE ...
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1answer
80 views

Floating supply voltage

I'm building a device to, among other things, measure a few voltages from different power supplies that are expected to be floating. Because the user might do silly things like connecting them in ...
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0answers
338 views

Potential difference between DC floating power supply and earth ground

I have a question about a simple DC floating power supply: it is as simple as possible, secondary coil -> bridge rectifier -> filter cap, as shown on the figure below. If I connect the input of the ...
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2answers
597 views

Star point in schematics

I read somewhere that in a mixed signal ckt , the analog part and the digital part are supposed to be better when they have different power rails and ground lines , but to avoid floating of the ground ...
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7answers
2k views

Getting two (or, one and a half) outputs from a single pin

I am doing a project with an ATtiny85 and of course I'm short on I/O pins. One idea I had was to use a single pin for two outputs (let's call them EN and DATA). simulate this circuit – ...
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1answer
96 views

Altium 17: Multichannel Design “contains floating input pins”

I get Net SCL/SCK contains floating input pins (Pin U1.1-4,Pin U1.2-4) as the only error after compiling the project but I don't know why. The clock signal as well as V+ is shared among the ...
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1answer
85 views

Function Generator - Signal without Neg or Gnd reference

I have a new PC based function generator (very cheap), and an old BK Precision function generator. The old BK Precision can output a signal without the ground or negative reference lead from the BNC ...
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2answers
171 views

Is it bad to leave a filter capacitor floating?

The circuit detail presented is a gyrator filter that is one of two that hang out in the feedback loop of an opamp, creating a "low" and "high" tone control for audio. (The "low" section is shown) I'd ...
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3answers
219 views

Can a 1:1 transformer prevent the SMPS noise of one load from reaching other loads plugged into a mains outlet?

It's my understanding that a load which has a SMPS can put noise back onto the power cord, which could reach another component that's plugged into the same outlet. Is it true that a 1:1 transformer ...
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54 views

With a 1:1 transformer, what differences in noise reduction will a floating-neutral secondary exhibit, compared to a grounded-neutral secondary?

Assuming the core, the windings, and the Faraday shield are all of the same design, compared to a transformer that has a grounded-neutral secondary, can floating the secondary's neutral have any ...
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278 views

Who do IGBT rectifiers have floating gates (unlike MOSFET rectifiers)?

When I search Google Images for "IGBT rectifier", I notice that they all appear to have floating gates. But don't IGBT's have gates like the ones on MOSFET's, in which it's insulated from the other ...
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2answers
489 views

How to check if pin is floating or connected to ground?

I am using a DC jack which has 3 pins. 2 for power and one pin which is connected to ground when there is nothing plugged into the jack and disconnected from the ground when the jack is plugged in. ...
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2answers
90 views

Do I need PSUs with similar current rating when I connect them in series?

I need a 48V power supply with 20-25A so I decided to use old ATX power supplies I have lying around. I know already that the series of ATX PSU can be used to charge lithium packs for RC planes, it ...
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3answers
1k views

{IC pins} Leave Floating vs Leave Open?

This might be a newbie question, but I have always heard these terms interchangeably and never given it another thought. Recently I have seen them used differently in data sheets for a board I am ...
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1answer
54 views

multiplexer with floating outputs

I have actually a solution based on a multiplexer (CD4051) which drives 8 outputs, either at 0V or 3.3V (the input is at 3.3V). Each output of the multiplexer drive a NMOS and the goal is to have a ...
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72 views

What would happen if I touch the chassis of a floating oscilloscope? [duplicate]

I need to do some ac line voltage measurement with an oscilloscope, so I read that I will have to remove the PE ground connection to avoid the shortcircuit between the N and the PE referenced osc ...
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1answer
112 views

How do floating voltages affects circuits/systems?

I was at a talk recently regarding robustness testing. It was separated into parts: Uncontrolled and Controlled. Uncontrolled involved applying high floating voltages to various pins and logging the ...
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2answers
311 views

Floating voltage on metal shelf

I just setup a pepper seed starting shelf using a metal shelf from a Swedish furniture outlet. The shelf has no electrical contact with the 5x T8 bulbs which are hanging on plastic zip ties. The T8 ...
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1answer
53 views

Using a DAQ with a programmable power supply floating input

I have a programmable power supply (Sorensen DCR300-16T) that requires a floating programming voltage. From the manual: (3.9.1) In selecting a signal source, the following should be considered: ...
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2answers
202 views

Noise pickup in fully floating circuit

I'm using an ac coupled noise matching transformer to measure the voltage noise of a low ohmic sample as a function of bias current. The complete circuit is in an enshielded enclosure. When the ...
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5answers
827 views

How is the input not floating when there is a pull-down resistor? [duplicate]

I am wondering why the input to D2 will not be floating when the switch is open. If the switch is open, wouldn't it act like a mini antenna and provide a random input to the D2 pin?
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1answer
103 views

What are the risks of running a floating ground through insulated wire underground?

I've created a circuit that is powered with a floating ground off of a transformer. I'd like to count pulses from a meter by having the meter complete the floating ground side of the circuit but I'm ...
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1answer
745 views

Connecting Two Grounds Together

I'm trying to understand what would happen when connecting two grounds from diffident power supplies together. A more in depth explanation of what I'm trying to accomplish is here: Connect Arduino to ...
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3answers
442 views

Understanding microcontroller ADC input pins (atmega328)

If I set up the ADC on the ATmega328 to read from a certain ADC pin, what state is the ...
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0answers
128 views

XMFR or input supply issues?

I have a 120VAC house outlet (It is a Standard US house socket in Texas.) with 120V Line and 0V neutral and GND powering a 120V / 0V Primary on a XFMR with output taps at 0V, 300V, 350V and 400V. When ...
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4answers
2k views

Why would you need a floating signal on a board?

I read the following from a book titled "An Embedded Software Primer" by David E. Simon. (23rd print Nov/2014 - Page 16) If no part on the circuit is driving a signal, then that signal is said to ...
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1answer
126 views

Floating inputs and Vref on a voltage subtractor (PWM to Gate converter)

A little background: I'm trying to extract a gate signal from someone else's circuit (ckt1) so that I can synchronize events in my design (ckt2) to a sequential trigger in theirs. First problem is I ...
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0answers
715 views

Design for a balanced (positive and negative) HV DC regulator

I'm trying to design a high voltage DC regulator for driving a PZT that will provide both +200 and -200 V outputs referenced to ground. The input is a rectified AC waveform that will provide UK mains ...
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1answer
457 views

How to prevent floating input for this system?

I have a simple system where a motor speed is controlled by a voltage signal via a circuit. Below represents the system where A is the voltage signal device; B is the circuit and M is the motor. The ...