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Questions tagged [isolation]

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

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How to isolate RS485 (A and B) from existing transceiver? Check attached circuit diagram, is it correct?

I have a controller with an RS485 transceiver, specifically the IS8489EIBZ-T, which is not isolated. I want to connect a BMS system to the output of this transceiver. After some research, I found a ...
mechaTronics Tech's user avatar
1 vote
0 answers
55 views

Isolation transformer triggers the RCD in the lab [closed]

I am an electrical engineer, and I work in a lab environment. For some inverter measurements, we have bought an isolation transformer, but it triggers the RCD (GFCI for North America) in the lab when ...
Behemoth's user avatar
1 vote
0 answers
62 views

Safety considerations for designing Mains Voltage Sensing Circuit

I'm looking to design a circuit to measure AC mains voltage and current for protection purposes. I'm considering using the ADS131E0 ADC by Texas. The IC is made with power-line monitoring in mind. On ...
Dinis's user avatar
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0 answers
27 views

DC isolation - 3 separate circuits with same power source and shared I2C

I am trying to build one small project and based on the needs I need to isolate few components but also keep them connected using I2C. I was doing a research and found few DC DC isolator converters ...
Peter Bašista's user avatar
2 votes
2 answers
194 views

Designing Optocoupler circuit

I'm trying to learn how to design an optocoupler using 6N137. datasheet : https://www.vishay.com/docs/84732/6n137_vo2601_vo2611.pdf There is no CTR (current transfer ratio) value or graph in the 6N137 ...
Mhan's user avatar
  • 335
1 vote
1 answer
91 views

How to isolate nickel-chrome wire?

I want to heat up a stainless-steel pipe using a nickel-chrome wire by wrapping the wire around it and using a 12 V / 2 A DC adapter as a power source. I wrapped kapton around the pipe and also ...
Khalident's user avatar
0 votes
1 answer
50 views

ESD on two different materials

I am conducting ESD testing on two types of materials with a setup that closely follows the 61000-4-2 standard. We have incorporated both isolation material and a ground plane into our setup. When I ...
DRF's user avatar
  • 526
0 votes
2 answers
51 views

Safety considerations when measuring an analog signal across an isolation barrier

I'm designing a PCB that is powered by 230V AC and switches 5 heating elements via 5 Triacs. As a best practice I included optotriacs for driving the main triacs and used a 230V to 5V buck converter ...
DreiDe's user avatar
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1 vote
0 answers
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RS232 isolated communication via MAX3250

I have a two diffrent boards. One of the board is send the SoC and other things to Charger Board. While charging progress starts I want to isolate this to device because battery ground is isolated to ...
MSB's user avatar
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3 votes
2 answers
103 views

My isolation transformer has its protective earth connected to the output neutral. How should I rewire it for my home lab for "DUT probing"?

I have a rather sturdy isolation transformer in my home lab and I just realized that the primary side earth is not only connected to the output side earth but also to the output side neutral. I don't ...
pipe's user avatar
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0 votes
2 answers
85 views

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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0 votes
1 answer
52 views

Power Supply is arced and fuses opened

Note: PFC circuit is bypassed I have my own designed circuit and this circuit is get input of 220VAC/50Hz. Inside of circuit bridge rectifier and filters are exist with this circuit we get 320VDC. So ...
MSB's user avatar
  • 77
0 votes
1 answer
77 views

Should I merge GND and COM?

I'm building an dual supply op-amp circuit. I'm using a Isolated DC-DC converter module to supply op-amp with +-15V. The module ouput is labeled 'COM' and isolated from the input GND. The input signal ...
Mustafa Turhan's user avatar
3 votes
1 answer
115 views

Choosing Y-capacitor value for isolated DC-DC

In an isolated DC-DC converter datasheet (link), the Y-capacitor recommended is 270 pF. How is this value arrived at? And would the intended use of the Y-cap be achieved if a higher value like 1nF is ...
EarthLord's user avatar
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2 votes
2 answers
325 views

Will an isolation transformer have a noticeable effect on mains hum? Also critique my DIY transformer idea

(Uber-edit - it has come to my attention that I am an ignoramus. This post is being left in place not to highlight my stupidity in particular, but to serve as a warning for others who think ...
neural's user avatar
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0 votes
2 answers
51 views

high voltage moderate frequency galvanically isolated current measurement

Given a conductor carrying a sawtooth wave of anywhere between 0.1Hz and 855kHz up to +-1.5kV) and anywhere between +-(1µA...20A)(maximum 650W) i want to measure the current with about 5MS/s (so the ...
user338269's user avatar
-2 votes
1 answer
28 views

Analog sensor isolation for Raspberry Pico analog pins [closed]

I’m designing a logger to collect data from a thermocouple (may be any type) using Raspberry Pico (3.3V). I want to isolate analog pins. As per my study inductive isolation can be done to transfer ...
Lean345's user avatar
10 votes
3 answers
2k views

Why does this "hot chassis" TV have the inputs isolated by an active circuit instead of just a capacitor?

I was looking at adding a Y/C video input to an old TV. But it's got a hot chassis so it's not a trivial task. I thought i could just capacitively couple the Chroma line, but then i looked at the &...
hjf's user avatar
  • 1,181
10 votes
7 answers
2k views

Puzzle how isolated RS-485 (ADM2582) sends signal without signal ground

Galvanically isolated RS-485 surely needs a signal ground, which leaves me puzzled about the following circuit -- which apparently sends the RS-485 signal correctly without the isolated grounds being ...
jonathanjo's user avatar
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2 votes
1 answer
51 views

Isolation voltage spec in transformer

Could you please help me understanding this transformer spec? I am planning to use HCTSM80101AAL transformer and I would like to make sure that I am referencing the proper specification for voltage ...
Alia Sana's user avatar
0 votes
2 answers
89 views

How is my isolation transformer not short circuited?

I received a 3 phase 240 to 208 isolation transformer, and I am unsure how the current configuration (as it was shipped to me) would not cause a short circuit. When I do an ohms reading on the high ...
JCoder's user avatar
  • 11
0 votes
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
1 vote
2 answers
84 views

Isolate battery from a charging circuit... to use a stronger charger

I have an inverter that currently uses a single 7 Ah lead acid battery. While the rating of the inverter is sufficient to my purpose, the battery does not provide nearly enough run time, and being ...
NapalmKnight'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
3 answers
427 views

How to isolate audio signals from each other using op-amps with the same single supply?

Reuploaded corrected picture, as the old one was with confusing ground connections: I am new here, so please be patient if I'm doing something wrong. I really need some help as I can't figure it out ...
Manac's user avatar
  • 13
0 votes
0 answers
70 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
1 answer
58 views

Half-bridge driver ground loop elimination

I built this half-bridge driver using a generic Schmitt trigger/hex inverter IC and a 555 timer as the square wave generator. By varying the value of the resistors, the dead time can be adjusted and ...
ElectronicsNoob's user avatar
2 votes
1 answer
174 views

PoE: PSE isolation requirements

On the robot I'm currently designing, there will be several connectors with PoE ethernet and supply voltage (0 V, 24 V) and some other signals (referenced to 0 V). I'm unsure if I need isolation for ...
Sandro's user avatar
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0 votes
0 answers
31 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
1 vote
1 answer
335 views

RS232 : dedicated signal ground or common with power ground?

I'm designing the PCB for a robot, where I plan to add some connectors for external RS232 tools (provided by the client). Each connector will provide power (either 24 or 48V, at 5A max) and an RS232 ...
Sandro's user avatar
  • 7,697
0 votes
3 answers
170 views

Eliminating Noise from Audio Amp Board Input

I made this project by shajeeb (linked below), and I am having trouble with noisy ground lines. The circuit I made is the same as the diagram below except for where I connect the speaker and amplifier ...
Jameson Gatewood's user avatar
0 votes
2 answers
76 views

Isolating USB3 with an ADUM4160

I've not played with USB much besides the ordinary FTDI UART bridges. Recently, I have reason to use an FT601 with a USB3 port configured for super-speed operation. As this is connected to a fairly ...
instrumental's user avatar
0 votes
0 answers
120 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
1 vote
0 answers
87 views

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
  • 544
0 votes
0 answers
68 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
2 votes
1 answer
133 views

Isolated flybacks in series to generate high-voltage [closed]

I'm considering placing isolated flyback converters secondaries in series such as the image below. I want to drive the transformers individually using synced clocks (such each transformer has its own ...
Curious Diode's user avatar
0 votes
1 answer
253 views

MCU signal isolated and Amplified (Optocoupler+BJT+Mosfet)

I've com up with the following design. I feel I've used too many components, don't know. but I have some reasons for anything included in the design. PULSE_A : some low frequency (50~1000Hz) low duty ...
Bikay's user avatar
  • 73
1 vote
1 answer
59 views

Wurth transformer secondary pins on left and right side of transformer

I am looking to use Wurth Transformer 750310988 and I have noticed its pinout is very bizarre. My application is I want to float the secondary of this transformer up to 500VDC and provide a isolated ...
Curious Diode's user avatar
2 votes
3 answers
531 views

Isolation transformers and short circuits

For some quick background and info: I'm a relatively fresh (~2y/ experience) EE in the solar field. I work in the R&D department of my company. My country operates in a 230/400V 50Hz grid. We are ...
A.K.'s user avatar
  • 29
0 votes
3 answers
445 views

Understanding RS422 and choosing drivers

I want to communicate 2 MCUs using RS422. I need to have some isolation, so the driver should have 3.3V side and 5V side, isolated. All I can find in the market are half-duplex drivers, I understand ...
Developing Electronics's user avatar
4 votes
0 answers
76 views

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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1 vote
2 answers
192 views

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
3 answers
204 views

In aircraft power supply, why is the neutral not connected to chassis GND unlike household utility power?

Usually the chassis of any household equipment is connected to earth ground for safety. Part of the culprit is neutral being connected to Earth ground. (Reasons are mentioned in this post.) My ...
Dynamic_equilibrium's user avatar
2 votes
0 answers
59 views

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
  • 121
4 votes
2 answers
155 views

Isolation Topology in SMPS

I have been researching SMPS designs as a hobby recently and finally have the courage to build one for theoretical and practical understanding. I have chosen an isolated design looking at several ...
Vadim Belogorodsky's user avatar
4 votes
9 answers
2k views

What options exist for isolating a high power DC analog signal? [closed]

I have a high power DC signal that can range from 0-325 VDC. The source is capable of delivering up to around 150 amperes at 325 volts. I need to monitor the voltage as an analog signal by reading it ...
I Weld's user avatar
  • 49
0 votes
0 answers
74 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
  • 275
1 vote
2 answers
313 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
1 answer
124 views

Isolate current flow in Ltspice using switch

I am trying to control the flow of current by the switch SW, I have used an independent current source I. However the switch is ineffective to isolate the resistor R1, because the switch is basically ...
Avijit Das's user avatar
0 votes
1 answer
91 views

Do I need to connect a resistor at the output of an isolated DC-DC converter module?

I am using D050505S-1WR3 in my design for powering an isolated CAN transceiver. The can transceiver is the ISO1042BDWV from TI. Below is the schematic of the power supply and CAN transceiver. During ...
Confused's user avatar
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