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Questions tagged [isolation]

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

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Isolation for USB 2.0 High Speed (480 Mbps) [duplicate]

The fastest isolators available a a reasonable cost are 150 Mbps per channel. High Speed USB has a data rate of 480 Mbps. So how do you isolate a HS USB? The first thing that comes to mind is to ...
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2answers
36 views

Isolate a digital signal that changes its amplitude

I have to isolate a digital signal that has the following characteristics: frequency: between 1 and 1000 Hz amplitude pk-pk: 12V offset: 0-6V With "offset" I mean the actual voltage may change from ...
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56 views

Balanced speaker level to unbalanced line level

I am attempting to take a balanced audio signal at speaker level (~10V peak to peak) and connect it to an unbalanced 3.5mm jack at line level. I found this schematic which suggests using a transformer ...
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2answers
67 views

What is the purpose of galvanic isolation?

Is it correct to say that the primary reason to have galvanic isolation (ensuring minimum clearance and creepage distance for required voltage of power circuit between HV and LV) between the HV power ...
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2answers
68 views

AGND and DGND connection using flash ADC, totally stumped

So, I am designing a PCB with the classic scenario of having both sensitive analog signals and noisy digital signals... Analog and digital regions are separated. the have their own gnd planes and ...
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2answers
49 views

Isolation Amplifier Gain Problem

I'm having a little trouble with an isolation amplifier. I'm using an HCPL-7800 isolation amplifier, in the circuit format provided by the manufacturer as a test circuit, and feeding it low voltage DC ...
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3answers
48 views

Isolate low power i2c ADC

I'm using the MCP3421 to read voltages from thermocouples on battery power. I would like to get this working over USB but I think the low common-mode range of the ADC could be problem so I am ...
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1answer
36 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) ...
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39 views

CAN Isolator function

Why is a CAN isolator used? Known background theory: The CAN isolator is used in order to protect against surges / EFT's, reduce the effect of ground loops (common mode EMI) and eliminates voltage ...
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45 views

Creepage Distance in Altium Designer

I have a design with a high voltage and a low voltage part. Between the two I need to have a creepage distance of 8mm. Some optoisolators I use in my design are not wide enough on the PCB footprint, ...
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1answer
79 views

Controlling a high voltage relay by a PC USB

My 2.1 speaker's transformer is consuming active power even when the PC is off. I know it because it is always warm. Thus, I want that only when my PC is operating the transformer will get the AC ...
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3answers
452 views

RS 485 ground signal and chassis

I have a shielded twisted pair running from one device polling several devices in an RS 485 loop. The conditions: The devices are in parallel as they should be. The termination resistors are in ...
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2answers
68 views

Automotive signal isolation - alternatives to optocouplers

I'm working on an automotive project, where I'd like to interface various digital signals to an MCU. The signals can either be ON/OFF (e.g. radiator fans) or measurements of pulse frequency, width, ...
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4answers
70 views

Proper insulation of wires connecting to the submersible pump (5V)

I'm building a simple plant watering station, which uses a relay-controlled submersible water pump (this one). The intent is to submerge the pump into a large enough water container to avoid frequent ...
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2answers
82 views

How can I split a 5v power supply into 4 isolated (no shared ground or live) channels?

I need to power a number of tp4056's with the battery outputs in series (using tp4056's because I have a bunch already, and because I want to be able to add more cells in series later). If I do this ...
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3answers
704 views

How does Galvanic isolation work?

I am unable to understand how does galvanic isolation work either via an optocoupler or a transformer. In an optocoupler, the input side current caused LED to emit infra red light which basically ...
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1answer
127 views

Insulation Voltage of Aluminum PCB - With and Without Electronic Components

We are working on a product that contains an LED module consists of 66 LEDs (33s x 2p - 100VDC load voltage). We'll use aluminum PCB due to the thermal requirements but the customer requirement ...
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2answers
69 views

What to look for in an isolation transformer?

What do you want from an (isolation) transformer besides it having the minimum voltage/current/power(/frequency?) specs that the to be isolated device needs? Does it matter whether the transformer is ...
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1answer
45 views

Isolating Power in Communicating 5V Sub-systems

I have been plagued by a sensor sub-system which, when connected to my base micro-controller platform, intermittently causes issues that I would categorically associate with power sequencing issues at ...
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2answers
59 views

Current loop protection from wrong connection of the wires

I have built a current loop protection circuit based on the topic Using a microcontroller ADC to measure a 4-20mA sensor It works good. The next step is I want to protect the input of the circuit ...
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0answers
30 views

Increasing isolation in power splitter

I want to use This module\minicircuit Power splitter. I am working on the 2.4GHz to 6GHz band. The isolation parameter on the stated for these frequencies in the "Typical Performance Data" table is in ...
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0answers
39 views

A heat resistant connection between power supply and a resistive wire circuit (heat grid)

I'm wondering about methods to isolate thermically from the power source a resistive wire circuit (main function: to heat things). I'm sure there is a non-DIY solution (i.e. "buying something") which ...
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1answer
47 views

Convert dB to resistance

I am new to this, but I wanted to ask how it would be possible to convert a dB value into resistance. I've been looking at an isolated analog switch from http://www.ti.com/lit/ds/symlink/ts5a3359.pdf ...
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3answers
257 views

Shock from Capacitive Coupling

In an AC supply which is not earth grounded, I see a small amount of current flowing to ground from both wires of the supply (live wire has higher) even though the circuit is incomplete. It is due ...
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0answers
30 views

Isolation of circuitry from heat source

I'm building an electrolysis unit which will comprise a refractory crucible, containing the electrolyte and the electrodes. The heat will be generated from a furnace to aid the desired reaction. A ...
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0answers
62 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 ...
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1answer
74 views

Designing flyback converter - multiple isolated outputs

Can I treat 2 secondary coils with dual voltage output as one with double voltage for the purpose of calculations? This seems to be OK for all formulas based on output power as technically the ...
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63 views

Designing isolated flyback with multiple outputs

UPDATE: as suggested, I split this question into separate parts (links below). I left the last one here. It is so silly I am rather proud of it ;) UPDATE 2: it seems that breaking one post into ...
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2answers
146 views

Were do ground pins on isolation transformer go [closed]

The outputs from transformer have a ground. Is output ground earth ground? Isn't the whole point for those transformers not to provide earth ground potential? Example:
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4answers
45 views

Isolation with inverter

Say I used a 12v car inverter powered by a 12v brick connected to ac mains (no ground pin) to isolate a scope and bench dmm, the inverter has no earth ground. Is the equipment isolated? Is lack of ...
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2answers
191 views

Cheap isolated mains current measurement

I'm looking for cheaper ways to measure current in a load switched by optoisolated TRIACs, without losing galvanic isolation (no breakdown below a couple kV) between the microcontroller and the load. ...
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1answer
37 views

Isolation between measuring voltage from low current circuit?

simulate this circuit – Schematic created using CircuitLab I have a low current current circuit and I would like to be able to measure the voltage on one point of the circuit but have ...
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0answers
75 views

how necessary is an isolated DC/DC for an ESP32-wroom-32 digital circuit in an automotive 12/24v System?

I want to use an ESP32-wroom-32 into an 12/24[v] vehicle. To eliminate ground loops and separate the digital circuit. In my first circuit, I use an Arduino, an LM2596 step-down module, and ltv-826s ...
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2answers
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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2answers
68 views

what is the meaning of isolation of transformer between i/p to o/p is 1 kv & mains supply to body/chassis is 2 kv

I have to design a transformer with isolation factor as follows:- Isolation between i/p & o/p is 1Kv Isolation between mains supply to chassis is 2.5Kv How to calculate these isolation factors ...
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1answer
34 views

Isolation of voltmeter via DC->AC->DC conversion

I bought a combination ammeter/voltmeter which has the restriction that the measurement/display circuitry must be powered from a different source than the measured voltage. What is the underlying ...
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2answers
117 views

Safety: Mains step down transformer vs SMPS for bench power supply?

Between a mains step down transformer and a SMPS, which would be safer for a bench power supply? I cannot look inside the transformer in either case to judge the insulation quality. But, if the ...
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1answer
46 views

Dual battery setup

I want to make a dual battery setup on my car. Doing some research I came across the two main techniques to do this, both based on isolate the two batteries being fed from same alternator to avoid ...
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1answer
36 views

Do I need different isolations among long-wire switches?

I'm playing with an MCU board (like Arudino) to read the state of several switches in my home (i.e. magnetic switches). The wires between the sensor and the board are quite long: 15+ meters in a star ...
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1answer
71 views

galvanic isolation for lm555

Hi guys I am trying to implement galvanic isolation for my lm555 square wave generator. I am designing a marx generator so this is essential. I am new with transformers, at the moment all I want to ...
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3answers
315 views

Is galvanic isolation needed when the output voltage is higher than mains?

For a flyback converter, 120 V AC in and 400 V - 2000 V out, is it necessary to provide galvanic isolation between the input and output? First, from a safety point, would not having a direct ...
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1answer
81 views

Safety Standards for Low Voltage Systems

I am looking for safety standards which could be applied to the piece of equipment desribed below. Basically the piece of equipment is a housing which inherits a 24V 100Wh Battery (2x SBS60) and a ...
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1answer
672 views

Ground loop isolation of a USB-powered device

I have a device (Device 1) that is bus-powered via Full-Speed USB and that is drawing up to 400 mA from a laptop. Device 1 has a DAC that can output an analog voltage to another device (Device 2) ...
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2answers
61 views

isolating between two power

for better isolation and because of sparking at the contacts, it is suggested using a separate supply with optoisolation like an image attached, but in my design, I wave only one power supply and I ...
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1answer
62 views

Isolation for TO-247 Leads at High Voltage (1000V)

Regarding the fairly new High Voltage SiCFET Devices with operating voltages of 1200V+ in leaded TO-247 packages (or variants thereof): How to isolate the Gate-, Drain- and Source- leads (and ...
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2answers
155 views

What is the exact name of this type of transformer?

I know, it is a (1:1) isolation transformer [wrong, see answer], found in some power supplies. However, when I search on this I get all kind of transformers except these. I have searched with the ...
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5answers
157 views

Isolated mains sensor

I’m building a mains sensor that should be able to operate safely at a voltage of up to 650VAC. I’ve already built one before, that operated with 130VAC, which I successfully monitored with a MCU, and ...
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0answers
92 views

what is the function this capacitor on the circuit? [duplicate]

I would like to ask a brief question about the function of the capacitor ( C57 ) used in the circuit below the image taken from an applicaation note which is about Voltage Sensing http://www.ti.com/...
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1answer
79 views

Proper way to route high-voltage tracks near THT components

I think this is not a duplicate of this question. My design has the following constraints: type and position of connectors pinout assignments 260 VDC / 2A for high-voltage tracks 12V / 200 mA for low-...
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3answers
140 views

what happen if a high voltage connects to pc-based oscilloscope's ground?

What happens if a high voltage (for example 500V) is connected to PC-based oscilloscope's ground? In principle, nothing should happen, but if somehow the PC's ground and high voltage's reference tied ...