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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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 ...
11
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5answers
9k 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 ...
11
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2answers
14k views

Floating multiple sealed lead acid batteries in parallel

I know with multiple lead-acid batteries you should really charge them separately so that one battery doesn't try and charge another and waste power. But that holds true for the main charging process....
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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 ...
6
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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 – ...
6
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1answer
586 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 ...
5
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1answer
2k views

What to do with unused TTL and CMOS outputs?

Just about everything I've read on the Web, including on this site, say that unused TTL and CMOS outputs should be left floating. However, this TI article, Designing with Logic, states: Unused ...
5
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1answer
535 views

What is the purpose of transistor and zener in this circuit?

simulate this circuit – Schematic created using CircuitLab (simulation will not be correct because the diodes are added just by its name.) Hello, I am a student who is not really familiar with ...
5
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3answers
1k views

How to check if a DC power supply is a floating source?

Imagine a laptop power supply with 2 prongs and I'm using this as a power supply for a circuit, and the output of this circuit is an input signal Vin for a data acquisition hardware. How can I ...
4
votes
1answer
3k views

Pulling the circuit's voltage to the ground with grounded probe

When measuring a point on an isolated circuit board with my grounded oscilloscope, I fear my oscilloscope ground will pull the measured point to ground level but this has never happened, I am always ...
4
votes
2answers
510 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. ...
3
votes
2answers
343 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 ...
3
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1answer
479 views

Why are the dimensions of a floating gate layer in a MOSFET so thick?

For a floating gate MOSFET, in order to make the control gate work you have to(generally speaking) make the oxide layer thin(~100 Angstroms) as well as the ONO(Oxygen nitride, acts as an insulator) ...
3
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2answers
448 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 ...
3
votes
1answer
117 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....
2
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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 ...
2
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3answers
673 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 ...
2
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2answers
1k 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 ...
2
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2answers
297 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 ...
2
votes
1answer
151 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 ...
2
votes
1answer
681 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 ...
2
votes
1answer
1k 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 ...
2
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2answers
489 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 ...
2
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2answers
486 views

Why do we use pull up resistor with PIC?

I tried to find an appropriate answer for the question but couldn't find what I needed exactly. I found out that "Initially the output from the PIC is floating and we use the pull up resistor R7 to ...
1
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5answers
1k 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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3answers
698 views

Are capacitors floating power supplies?

I'm struggling with the concept of floating voltages. For a grounded supply I can connect one side to an effectively infinite ground and get full power. It may vary depending on its construction, ...
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2answers
467 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 ...
1
vote
1answer
80 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 ...
1
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1answer
39 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 ...
1
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1answer
119 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, (...
1
vote
2answers
48 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 ...
1
vote
1answer
136 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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2answers
277 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 ...
1
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2answers
224 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 ...
1
vote
1answer
167 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 ...
1
vote
1answer
144 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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2answers
424 views

Floating value when connecting to IC input

I'm currently having a strange issue with what I think is a 'floating' signal. The setup: I have a bank of inputs (which are connected to a resistor and LED acting as a pull-down) connected to inputs ...
1
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1answer
260 views

FPGA input pin internal floating

I am now occouring a FPGA pin damage problem. One of my pin is hardware connected to a 1.8V signal that will be switched on/off occasionally, while the port is not connected to any other logic gate ...
1
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0answers
43 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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1answer
157 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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0answers
519 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 ...
1
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1answer
185 views

FPGA + SRAM - floating inputs of SRAM during configuration of FPGA

I'm connecting SRAM to FPGA (Spartan 6). During configuration and during periods when FPGA will be down (for example I would like to turn off FPGA when external flash will be programmed by uC) address ...
0
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3answers
345 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 ...
0
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2answers
732 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. ...
0
votes
3answers
59 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 ...
0
votes
1answer
114 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
92 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 ...
0
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3answers
572 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 ...
0
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2answers
1k views

2N7000 behaviour explanation

I recently bought a 2N7000 transistor and though it was a cheaper replacement MOSFET compared to the STP55NE06 as I didn't need to handle high voltages and high currents. However it acted very ...
0
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4answers
97 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 ...