Questions tagged [isolation]

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

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How are electric water heating elements isolated?

From what I've seen and understood, electric water heating elements are usually copper tubes/pipes with electricity running through them to heat up the surrounding water. I'm not sure if the ...
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42 views

Flyback Isolation Transformer Alternative

I am using the mEZS84801A as a reference design as shown below. It uses the MP8007 PoE chip. I have modified and tested this PoE system successfully and my camera be powered and it can run at 1 ...
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1answer
58 views

Voltage Translation

back in electronics after 7 years and found that nothing is in my bio-disk gifted by god. now, i have a motor system that i want to make sure, no one cut the cable. apart from the 24volt motor power ...
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2answers
40 views

Can RF/switching PS noise travel backwards through a circuit through a power supply

In the schematic below there is a sensitive ADC and sensor with 4 MHz SPI lines from the ADC to a 3.3V MCU, along with a 1 MHz boost converter powering an LCD. Could switching noise generated from the ...
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3answers
69 views

isolating DC from dmx signal

I have a DMX controller using a 3 pin connector (gnd, data+ and data-). I need to connect it to some cheap chinese DMX lights. The problem is that the lights are powered over the same 3 lines using a ...
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2answers
78 views

Reverse-engineering RS485/Mechatrolink-II front-end design

I'm trying to reverse-engineer Mechatrolink-II front-end circuitry. Its physical layer is simple RS485 (with isolation transformer) running at ~10Mbps. Here is the schematic I obtained from the PCB of ...
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0answers
85 views

Massive pk-pk ripple on output using isolated DC-DC converter module

I'm having a very odd issue using an integrated DC-DC isolated converter module. As the module stabilizes, a massive pk-pk ripple is developing on both the output and the input. At first we thought ...
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5answers
1k views

Isolated audio without a transformer

I'm putting together a guitar pedal for splitting the signal to two different amps. One of the features I want to put in is a 'ground-lift'; isolating the signal to avoid ground loops between the two ...
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1answer
50 views

How does Mains Isolation work with the ACS71020 IC?

In the datasheed for the ACS71020 IC, it shows the typical application of the device in which current is passed through the chip and voltage is measured on the opposite side. I do not understand how ...
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0answers
37 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 ...
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1answer
64 views

Barrier and slot within reduced area on a PCB

Imagine this situation in a little area of your PCB: According to the worst case and used material, I need a creepage distance = 30mm. According some tables, clearance must be 30mm. First Red banana ...
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1answer
64 views

Should isolated GND be tied to logic GND to prevent ground drift?

In an industrial environment, let's say you have an isolated interface that connects to an external sensor or device. This interface separates both logic signals to your main board as well as GND and ...
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1answer
52 views

Isolated UART communication: Which side should send the supply for the isolator?

I am in a situation to establish an isolated UART communication between two separate PCBs. The first PCB regulates and sends the required isolated power of the second one. The UART communication will ...
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51 views

PoE Design Question

I am working on a PoE project that calls for a power to be supplied to a application circuit. The application circuit requires ~41W (24V, 1.7A). I am exploring using PD70201 as the PD controller. The ...
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2answers
64 views

If my circuit is electrically isolated, do i have to worry about a polarizing effect on my sensor's output?

If I am making a conductivity sensor one of the things it need to watch out for is polarizing the water. easiest way to do this is have the output output signal of the sensor have a +/-0.2V square ...
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1answer
33 views

Can an isoSPI interface work without isolation?

Ive got a LTC6820 that I will be communicating with a LTC6811 and they both use isoSPI but all the example diagrams show the connections going through a transformers and twisted wire like this: But ...
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1answer
22 views

How to archieve induction isolation from adjacent inductors on a plane, but no isolation from inductors outside the plane

I am thinking of designing a large wireless charging pad. The idea is to have many inductors in a grid setup, where when a phone is placed on the pad it starts charging from the inductors closest to ...
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1answer
56 views

Dielectric (HI-Pot Test) Failure on Ethernet Port

We have failure on Dielectric test between Power wire to Ethernet Port. Failure was observed near 1.7kV. After test Ethernet port was damaged (Phy chip). See attached Case 1 :- Where we apply High ...
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1answer
43 views

Replace speaker to retrieve audio signal (and isolate galvanically)

I'd like to capture sound from a speaker output. The system seems to be running with a small DC current (bias, so voltage across speaker is about 3 V), so the audio AC signal could be (de)coupled from ...
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1answer
43 views

Is it a routed slot the same than creepage concept and how to calculate slot width?

I was reading a high voltage pcb design guide and it talks about insulators insertions, routed slots, gradient rings, etc.. but it doesn't talk about creepage. As the creepage could be achieved by ...
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39 views

When I use two IR2110 for full bridge, dose supply voltage of IR2110 need isolation?

I found the question that explains logic supply voltage (VDD, VSS) and gate drive supply voltage (VCC) are not isolated. And according to datasheet reference circuit, it seems to be non-isolated ...
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1answer
48 views

USB ground loop isolation for multiple devices

I have a use case where I use JTAG debugger connected to the circuit under test. Circuit is powered from a desk PSU and measured via desk MSO. This would normally create a ground loop, so I use an USB ...
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1answer
64 views

Galvanic Isolation in Automotive Environment

I am using a linear regulator (MIC29302WU) to power a computer mounted inside my car; however, there is significant noise being passed along the ground of the regulator to the main computer. I ...
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2answers
51 views

Grounding balanced secondary isolation transformer for EMI suppression

simulate this circuit – Schematic created using CircuitLab Which is the best secondary connection to clean the main line power from EMI, line noise and HF harmonics by using an isolation 1:1 ...
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1answer
50 views

how to isolate coupled noise source in parasitic capacitance in high voltage pcb design?

I'm new designing a high/medium voltage (V <=10kV) with low voltage and low current (10mA). There will be only a few HV relays. Their coils will be triggered by LV. I have read some literature ...
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3answers
39 views

Voltage isolation at IC pin when Vcc=0V

I recently started a project that utilizes a piezo sensor to sense vibrations. The piezo signal is fed to a uC in order to detect vibrations above a certain threshold. However, the piezo's high ...
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88 views

Isolated Voltage Measurement

In my application I need to measure a voltage that is in the area of 50V, but my microcontroller has to be isolated from my power circuit. I came across the ACPL-C87A-000E IC. I followed the typical ...
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2answers
75 views

Optocoupler isolation necessary?

The circuit diagram below shows two possible options for a circuit: simulate this circuit – Schematic created using CircuitLab The difference between both circuits is the use of the ...
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0answers
76 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 ...
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0answers
20 views

Isolation of SD IO pins during off state

I have a project at the moment that uses a PMOSFET to switch the supply to an SD card. According to the SanDisk SD datasheet available here: Because there are clamping diodes on the CMD, CLK, and ...
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1answer
41 views

How to tell if the switch is open or closed on a mains line?

Imagine a circuit that may or may not be connected to mains voltage. If mains is connected, it is trivial to determine if the switch is closed, by using a zero-cross detector circuit. If mains is ...
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1answer
50 views

Monitoring open/closed-circuit on a mains line

I am building a custom refrigerator control circuit. The refrigerator is solely powered from a battery source, using an inverter. For power savings, the inverter should be off when the motor is not ...
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2answers
71 views

Do the photocouplers on this module have any possible purpose? [duplicate]

I purchased a number of these relay module boards off AliExpress. They consist of the following 16x relays, 12 volt coils A LM2596 setup as a buck converter 2x ULN2803A darlington arrays 16x 817C ...
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1answer
74 views

What can be the reason multi-meter shows continuity even though there is isolation?

I'm dealing with a module where the block diagram is given as follows: The datasheet can be found both at here and an alternative one here. When I perform a continuity test with a multi-meter ...
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1answer
45 views

Is there a problem connecting PSU grounds to earth for an isolated signal chain in this scenario?

For a precision and simultaneous analog signal data acquisition; several force, temperature and acceleration transducer outputs are coupled to a daq board input channels through signal conditioning ...
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4answers
3k views

Interfacing a button to a microcontroller (and PC) with a 50 m long cable

I am designing a board that will be plugged into a computer and will read the status of a button ~50 m away in an office environment (it's actually a lot closer, but the cable is long). I think ...
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1answer
106 views

Full wave rectification with only an antenna input?

I am designing a receiving circuit and would like to do a full wave rectification of a sine wave signal received from an antenna. My problem is figuring out how to isolate the two ground signals of ...
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2answers
60 views

Isolating main power traces on backside of the PCB

I am currently making a build-in PSU for my own audio-effect-rack-thing. The internal PSU consists of two print-transformers(THT), one for 6VAC and the second one for 9VAC. These are also pretty low ...
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0answers
61 views

Whats the best type of connector for test equipment? [closed]

I am selecting the components to use for a tester I am developing. I am looking at various types of board to board connectors. The requirements are: Rated to least 2A. Rated to ~200v. *High ...
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1answer
120 views

Transformer Insulation - High Voltage can Jump Through Ferrite Core?

First of all, I really searched the topic on both EE.SE and Internet but could find nothing. If this is asked before, please forgive me. As I stated here earlier, I was working on an HV amplifier. ...
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0answers
37 views

Automotive 12V Analog and Digital input coupling and isolation

There are numerous questions on SE about classical automotive signal adaptation to microcontrollers. The circuit below uses a few common techniques for analog signal interfacing when a ...
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1answer
173 views

Does CANbus need to be isolated?

In my design - rugged computer - I have connected the digital gnd to the isolated CANbus gnd by mistake. Does the CANbus standard state that it has to be isolated? Can that connection harm the CANbus?...
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1answer
53 views

How do some instrumentation amplifiers handle such wide common-mode input voltages?

In a previous question, I asked about the detailed construction of in-amps. Now, I'm curious about a feature that some of them have that I'd like to know how they achieve: I used an INA286 in a ...
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2answers
95 views

Analog Isolation Question

There appears to be several options out there when it comes to isolating analog signals. This topic has been addressed on this website in a few forums as well. The problem for someone such as myself....
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1answer
50 views

What is the purpose of a schottky/zener couple on an isolated flyback topology?

This isolated flyback topology has been generated by TI's webench. It's a classic schematics with a feedback going through an optoisolator. There are, however, two diodes connecting the switching ...
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0answers
73 views

DALI optical isolation of signal, but no power isolation?

The DALI standard suggests a separated power supply, because the DALI control lines are not galvanically isolated, so mains voltage may appear on the lines (and the standard suggests that DALI devices ...
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1answer
78 views

Disabling isolation to reduce noise from EMI

A technician was suggesting we try connecting an isolated ground (described below) to a non-isolated ground suggesting it could reduce EMI noise and possibly fix an issue we're seeing (which we don't ...
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2answers
142 views

I2C bus isolation for dummies

Consider you have two devices designed to be I2C masters in same bus. However, only one of them is operational at a time and the other one is completely powered down. In my case the devices have ...
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1answer
77 views

Is isolation between user accessible circuits and protective earth necessary for safety?

First let me say that I understand that this question is best answered by someone familiar with relevant standards (whatever those may be). Let me give some background. When I'm designing a board at ...
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0answers
39 views

Negative feedback optical amplifier

Why the feedback network is necessary in this optical amplifier ? How the circuit would work without the feedback photodiode ?