Questions tagged [isolation]

Allowing for the flow of power or information without shared electrical nodes

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Mixed pollution degree creepage distance

Say you need to comply with a creepage distance but you can't do it under a specific pollution degree. I had 2 scenarios where I had mixed pollution degrees: The creepage distance is almost enough ...
HatimB's user avatar
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Erratic and confusing I2C behavior between ATSAMD21G18 and A89307 through ISO1644 isolator

I'm working on a BLDC driver using Allegro's A89307 controlled by an isolated ATSAMD21G18 via TI's ISO1644 I2C digital isolator. The simplified I2C connection is shown below, I omitted all the bypass ...
Jess S.'s user avatar
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Using the phase side of the line as ground for an isolated dc/dc converter

This evaluation board mention connecting the GND of the board to the phase side of the line in order to use a shunt to measure current from the high side. In this example they use a capacitive power ...
GmodCake's user avatar
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Isolating low-current, low-voltage digital signals

I'm working with a battery-powered sensor that allows reading its measurements using two digital signals - a clock and a data line. The clock speed is abount 3kHz. In addition to those two signals, ...
Florian Ragwitz's user avatar
2 votes
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Ground isolation in multichannel mixed-signal systems

There are some similar questions to mine but I have a few more specifications on top of them. Therefore, I am not 100% sure whether to ask as an iteration or present my own question on a clean slate. ...
falsterbo's user avatar
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What is the function of the capacitors and MOV on the outlet receptacle of this isolation transformer?

I recently purchase a used Tripp-Lite IS250 isolation transformer off of eBay. Here is the datasheet. It's a fairly open secret that these are not true isolation transformers suitable for a tech bench,...
riptusk331's user avatar
2 votes
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109 views

Will use of isolation transformer advise in lightning prone area?

I am working on a Radio Station located on a hill top. There are frequent lightning strikes during the monsoon season and they sometimes damage electrical equipment inspite of providing earthing. I am ...
seccpur's user avatar
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Isolator circuit for irrigation controllers sharing a common field ground

I'm attempting to add a second irrigation controller to my sprinkler system, however the controller doesn't have an expansion board, so I have to add a second whole controller to the mix. The zones ...
Matti Price's user avatar
2 votes
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In a forward converter, why do we need a separate controller for secondary side switches?

LT8311 IC is said to be a synchronous controller IC for a forward controller. Why do we need a separate controller at secondary side as the PWM pulses of primary side should dictate the synchronous ...
Divya K.S's user avatar
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Reducing Isolation Transformer Leakage

I watched this video and wonder if its complete separation of primary and secondary coils is the normal way to wind a low-power isolation transformer (e.g., 60Hz 120V 120VA). I particularly want low ...
bobuhito's user avatar
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How can we safely test a mains powered device?

We have small non-isolated 230VAC devices that transform mains to LEDs running at 32V, 20mA. The lights are directly connected to live, neutral and earth like a standard lightbulb would be. Since ...
sandervd's user avatar
1 vote
2 answers
153 views

What does 2xMOPP really mean

I am a student and I am designing a medical device that has a type CF applied part. I know the specifications that the applied part must comply (4kV of insulation, 8mm of creepage, <10μA patient ...
fox_rafa's user avatar
1 vote
2 answers
77 views

Multiple 4-20mA Transmitters from Common Referenced Analogue Inputs

I'm trying to come up with a scheme for multiple loop powered 4-20mA transmitters controlled from seperate analogue voltages, which all have a common 0V reference. My inital thought was to use an ...
Dan Twining's user avatar
1 vote
0 answers
108 views

How to get USB 3.x power but with data limited to USB 2.0 HS?

I am designing a device with a few interesting requirements. Due to power requirements, we need to draw 900mA, but due to isolation requirements, we're limited to the 480Mbps rate for our primary ...
mbengineer's user avatar
1 vote
1 answer
80 views

Isolated electronics for industrial application

I'm designing some boards for an industrial application. Basically, these are boards that verify the correct functioning of some power supplies (they measure the output voltage and check some POK ...
Federico Massimi's user avatar
1 vote
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293 views

Successful high voltage (400 V DC) measurement with isolation

I want to make a precharge system for an electric car for which I require voltage measurement. Here is what I am doing: Stepping the voltage down through voltage divider (0-5 V) range (high side). ...
goof's user avatar
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How do I know that the isolation tester is doing its job?

I am measuring the isolation resistance of a device where the measured value is within the range of just measuring with the test probes hanging freely in open air. 1 kV gives values in gigaohm range. ...
ISbit's user avatar
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How do isolated power amplifiers function when connected in series

I'm working on an isolated power amplifier with a differential output. This is achieved through two power op amps driven anti-phase to one another, simplistically it looks like this: simulate this ...
Jordan Cartwright's user avatar
1 vote
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186 views

Reading a voltage with isolation

I need to measure a voltage on a power rail without connecting ground between power rail and my measuring ground reference. I want to create something like an isolated amplifier but with a much ...
Singed's user avatar
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0 answers
204 views

Problem connecting two DC-DC converters in one circuit

I'm building an audio mixer for microphones, and have a problem with the power supply part. I'm designing this board to work with several voltages which are +/-15V, 5V, and 48V (for phantom power). I ...
Nino Sanjaya's user avatar
1 vote
1 answer
98 views

Two-ground issue

I've been working on a project which I need to rectify, filter and later lower the input filtered voltage (311V) to 12V, as shown in the picture making use of a flyback converter. The problem arises ...
Iron Maiden's user avatar
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Isolated UART communication with optocouplers

I want to create a universal PCB for projects requiring galvanic isolation. I'm not in need of fast baud rates, 9600 should suffice. My most common use will be with Arduino 5V/3V3. I want to ask if ...
Oxmaster's user avatar
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194 views

Question regarding isolation and level shifting

What are the requirements that make one choose between physical isolation and simple logic level shifter circuits when you have two devices communicating with each other. For example, a circuit ...
David777's user avatar
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How to interface a Raspberry Pi Pico to DMX / RDM

Years ago, I was looking at creating a stage DMX controller using AVR. Time moved on and the Raspberry Pi Pico has now been released. I'd like to revisit the project using a Raspberry Pi Pico, which ...
AJ.'s user avatar
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isolated Ground

I have a question regarding the ground connection of two isolated DC-DC converters. Is the connection advisable considering ground loops? Does it affect the safety? It is about the circuit seen below. ...
Rachidov's user avatar
1 vote
1 answer
157 views

Is additional isolation needed for inverter control circuitry?

I'm currently setting up a PV island system. Electricity is stored in two parallel 12V batteries which is then fed into a 300W 230V inverter. The load connected to the inverter consists out of several ...
sqrroot's user avatar
  • 11
1 vote
2 answers
184 views

Isolated RTD sensor

I need to read a Heatsink temperature with 5KV isolation. how is it possible? are there isolated temperature sensors ? or shall I design a board for it to isolate the output signals?
HsVz's user avatar
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1 vote
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575 views

Overvoltage and overcurrent protection to digital signal lines

I'm looking for a technology that protects digital signal lines like SPI, I2C, UART and general purpose I/O against overvoltage and short circuit. That is, protects the microcontroller's digital ...
Daniel's user avatar
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193 views

Rectified DC current measurement using shunt or Current Transformer

I am working on a project to design a controller for battery charging solution. A 3 Phase delta power (440 Vrms ph to ph) is given to a 3-phase Variac Transformer ( Variac is operated ...
Aksh Chordia's user avatar
1 vote
0 answers
47 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 ...
dinocroc123's user avatar
1 vote
2 answers
413 views

Preventing shock risk on isolated transformer secondary circuit

I fully understand that you cannot get a shock from either phase1 or phase 2 on the secondary of the isolated transformer, however you can be shocked by touching both. My question is how do you ...
Peter Gillham's user avatar
1 vote
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228 views

High quasi-isolated voltage measurement

I have to measure a DC voltage and an AC voltage around 100V. I found the circuit with an AD629 and one OP177. I simulated everything in Spice and it works fine, at least in the simulation. In ...
Momchilo's user avatar
  • 194
1 vote
2 answers
434 views

Galvanic isolation in automotive environment

I am using a linear regulator (MIC29302WU) to power a computer mounted inside my car. There is significant noise being passed along the ground of the regulator to the main computer. I verified this by ...
physiii's user avatar
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198 views

SPI Isolation : What is the point of the ADuM3151 etc

I was looking at ADI's isolators designed and marketed for SPI, such as the ADuM3151. I'm interested to know what makes these isolators special, in that what the point of them is. The isolators don't ...
Chintalagiri Shashank's user avatar
1 vote
0 answers
133 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 ...
Jim Fischer's user avatar
  • 3,044
1 vote
1 answer
66 views

Isolation Amplifier? Reading differential voltage on 600 V lines

I need to measure the voltage across the leads of a thermocouple, the thermocouple being physically connected to a 600 Vdc terminal. The instrument which measures the thermal couple (thermometer) ...
A.S.'s user avatar
  • 906
1 vote
0 answers
418 views

Need a system to isolate an external charge circuit in a vehicle

I am looking for some assistance with options in isolating 2 parts of a circuit. I have a 4G hotspot that I am using in the car, powered via the cigarette lighter socket (rated at 12V/10A) and a 5V ...
Braedon King's user avatar
1 vote
0 answers
91 views

Isolation Amplifier Design Issue

I modulate input signal with triangle wave to create PWM signal. When I am creating triangle wave I use astable multivibrator and integrating circuit. unfortunately there are offset at my triangle ...
ACK's user avatar
  • 11
1 vote
0 answers
676 views

PCB isolation strength VS pad-to-pad distance

Is there any estimation regarding the relation between PCB pad to pad distance and isolation strength? If the board is covered with the mask and the minimum distance is 2,9 mm which isolation voltage ...
Roman Matveev's user avatar
1 vote
0 answers
2k views

Can You Drive Back-To-Back MOSFETs (aka a Solid State Relay) Without Using An Optocoupler?

I was wondering if there was any way of driving back-to-back MOSFETs (with their sources and gates tied together as shown in the following image) without using an optocoupler? The reason is that ...
gbmhunter's user avatar
  • 451
1 vote
1 answer
449 views

ACPL-C79B problem

This is my first post on this forum. I have a problem with an isolation amplifier and i hope there's someone here who can help me out. Let me explain my situation. I use an ACPL-C79B from Avago to ...
user107585's user avatar
0 votes
0 answers
11 views

IEC61010 applicability for non-measurement category rated circuit?

I have measurement circuit that will be rated for CAT II 300V but do allow input voltage of over 300V up to 1kV. In IEC61010 6.7.3, "Insulation for secondary circuit derived from main circuits of ...
Cyclone1's user avatar
0 votes
0 answers
52 views

Why are USB galvanic/isolators needed on battery operated devices?

Why are galvanic/optical USB isolators used? I am an astro-photographer who does imaging at remote site locations on battery. I never encountered galvanic/optical USB isolation in devices until ...
Woxof Cavu's user avatar
0 votes
0 answers
26 views

Read voltage (isolated circuit) from 24S Li-ion battery pack and output 0-5 V signal

I am finishing up a EV-conversion and everything works well except the SoC display. The BMS I am using outputs 0-5 V to indicate the SoC but the output pin for this signal is broken from the previous ...
Luddbro's user avatar
0 votes
0 answers
66 views

Driving Gate from MCU (using 6N136 and TC4431)

This is my first time trying to use this optocoupler (6N136) I'm trying to control a MOSFET gate with the least switching delays (rise and fall timings) possible, while making the MCU isolated from ...
Bikay's user avatar
  • 73
0 votes
0 answers
49 views

Using a non-isolated DC power source for a microcontroller

I am designing a frequency converter for an approximately 200W three-phase motor operating at 220VAC. I intend to use a microcontroller for control and measurements. To cut costs, I am considering ...
WalterPH's user avatar
  • 440
0 votes
0 answers
60 views

What is wrong with my double pulse test Ltspice schematic? Gate pulse is not getting generated when I connect the gate driver for 800V application

What is wrong with my double pulse test LTspice schematic? Gate pulse is not getting generated when I connect the gate driver for 800V application. Any connection error?
Andr7's user avatar
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0 answers
56 views

How to eliminate the VFD noise affecting digital sensor reading?

I have a problem getting correct readings from a 5v digital sensor connected to an Arduino Uno board. I get correct reading until I start the VFD that drives a 3-phase motor. The sensor reading then ...
Shamooooot's user avatar
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0 answers
133 views

I keep Blowing up my i2C (ISO1540) isolator when plugging and unplugging my battery

I am using a ISO1540 to read the SMBus of some BB2590 batteries. The relevant part of the circuit is shown in the images below The issue that I am having is that sometimes when connecting or ...
Pepe's user avatar
  • 1
0 votes
2 answers
307 views

How to make a smart precharge circuit

I want to build a circuit that monitors the voltage at either end of the precharge resistor circuit. Since the load will have capacitance, I should expect an RC time constant curve on the load of the ...
JoeyB's user avatar
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