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

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1answer
45 views

Pulse transformer isolation on PCB

I have a question about pulse transformer ,regarding to isolation, EMI reduction and heating. My PCB has 6 layers (4 signal and 2 power planes) and I am using pulse transformer to isolate and convert ...
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1answer
48 views

Ground isolation

I am looking at ways to isolate my board and supply ground. I am feeding my board with a 40V dc power source. Now, the ground return of my board should not be connected to the battery return is the ...
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4answers
88 views

Short circuit when probing live ATX power supply primary section with voltmeter [closed]

I was probing around an old ATX PSU to inspect voltage levels in the primary section. The first 15 minutes went smooth (bridge rectifier inputs, big caps, Power IC Vcc, etc..) but as soon as I probed ...
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3answers
58 views

Boost converter for high side Mosfet

I recently came across an article explaining how to drive a high side MOSFET using a "separate isolated power supply whose ground and the ground of the MOSFET-based circuit are isolated". However ...
0
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1answer
48 views

What would the best way to filter high frequency noise? Decoupling/Bypass Capacitor? 1:1 Audio Transformer?

As many high end graphics card have high frequency coil whine and my particular one is causing whine on my diy studio monitors, what would be the best way to filter this noise? My studio monitors are ...
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3answers
116 views

Optocouplers with non-inverting logic

Here is the setup: I'm using the Arduino Mega's SPI functionality to send signals to multiple DACs. For digital isolation, I am considering the HCPL-2631 or the ACPL-064L. The problem with these two ...
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0answers
59 views

Using optocoupler on data pin to control 64 WS2812B leds by Arduino

I have 8x8 RGB WS2812B LED matrix and I need to isolate Ardunio (connected to the PC USB) from LED side of the circuit - 5V, up to 5A power supply. I heard that optocouplers are good for separating ...
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0answers
79 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 ...
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2answers
45 views

SPI Isolation with Open Drain MISO

So I am trying to interface a slave device to a master uC through an ADUM4151 SPI Isolator and am getting confused on where I need pullups for the MISO line as I see it a few ways in reference ...
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3answers
48 views

Can I ground the negative DC bus of a variable frequency drive?

Suppose I have a typical VFD: rectifier, DC bus caps, inverter, feeding a motor. In general it would not be advisable to tie the DC bus to earth ground, because the AC line may also be referenced to ...
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2answers
61 views

Isolation, level shifter [duplicate]

I want to to shift a signal which is varying from 1.2 to 3.3 volts ( a shifted square wave) to some other ground. I don't how to do this. Frequency of this signal is 10 kHz with duty cycle around ...
3
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2answers
97 views

Isolation transformer and AC potential between grounds

Wisely (I think) after connecting my DUT (Tektronix 2710 Spectrum Analyzer) to an isolation transformer, I measured AC voltage between the DUT chassis ground and my scope (Tektronix 2440) ground lead. ...
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2answers
81 views

Timing Issues with Optically Isolated Data Signal

I have been working on a system that requires data transmission between two devices powered by separate supplies. I have based my design on the MIDI-hardware Spec, as I'm comfortable working with that ...
1
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1answer
64 views

Why is ground shared between primary and secondary side in LT3750 circuit example

LT3750 is a capacitor charger controller IC. The sample (typical application) circuit in its datasheet shows an otherwise isolated secondary side sharing a ground with the primary side. A PCB layout ...
1
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0answers
49 views

Isolated CAN and Onewire

I have a bord where HV is present and one where only LV is presented. On each board is an Onewire und a CAN bus. How can I isolate the buses? I found for CAN this: ...
3
votes
1answer
166 views

How can I use an oscilloscope to measure voltages that are referenced to nodes several hundred volts apart?

In my organization, we often use four-channel oscilloscopes to check out products. Each probe reference might be several hundred volts away from the others, which makes using standard scopes ...
1
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1answer
90 views

How to isolate the microcontroller from power source?

I'm fairly inexperienced in electrical engineer so forgive the simple question. Using a microcontroller (Netduino) and two 8bit shift register (serial in, parallel out) I'm controlling 16 LEDs. The ...
0
votes
1answer
91 views

audio bleed between separate op amp channels

I am wanting to use two single-channel op amps to control the two audio input channels independently from one another. Both op amps (TL071) are on the same circuit board. The problem I'm experiencing ...
0
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1answer
22 views

Is there a way to measure current and fault current better than the ACS716KLATR-6BB-T

I need to measure 2.5A (ac) and detect fault current. Currently I am using a Isolated Current Sensor with Overcurrent Detection ACS716KLATR-6BB-T Datasheet I am using this part because space is the ...
2
votes
2answers
81 views

Do we need isolate the MCU from the relay driving transistor

This question came to me when I saw this question driving a relay with transistor and Opto-isolator. As Olin Lathrop had pointed out in his answer, relays already provide isolation between the coil ...
3
votes
2answers
86 views

Is there any bidirectional IC with on/off state?

I need a bidirectional IC with on/off state. In on state, IC should have very small impedance on the line. In off state, IC should provide very high impedance to isolate the bus. It's for an ...
0
votes
1answer
47 views

What design considerations determine what kind of power supply I should use for a high-side FET?

I'm presently considering building a half-bridge converter, which means I have a transistor that's not tied to circuit common. To drive it, I'll need some voltage supply referenced to its source. This ...
5
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2answers
138 views

Opto-isolator output from collector vs. emitter

I have an Isocom ISQ2X quad opto-isolator (datasheet) that I will use to drive a logic input. The opto-isolator's simplified model given by the datasheet is pictured below. The transistor base pin is ...
0
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1answer
42 views

How can an isolating tape be used as a connection to the human body?

I'm making this project: Drawdio There are 2 connections with the human body: one via the graphite and the other with a grip made of isolating tape. I don't see how this work. This tape isolates the ...
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2answers
115 views

Capacitive Galvanic Isolation [closed]

One can create a very cheap and easy to build capacitive galvanic isolator for low freq (audio)? In+ --||-- Out+ In- --||-- Out- Adding resistors does not help ...
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2answers
122 views

Is GND isolation required to parallel a large number of power supplies

Suppose I have something like 50 independent switching regulators all tied a single load and ideally sharing current. I could provide isolation for each regulator using a diode. simulate this ...
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2answers
104 views

Self-powered USB device isolation

I'm designing a USB device (a 3D printer board) which I want to power from an old PC power supply and use the USB only for communication. My understanding is that both the power supply and my PC are ...
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0answers
69 views

How to properly isolate when building a case for Arduino/Raspberry Pi?

I'm building a project will will use a Raspberry Pi, or maybe a similar little board. However, I'm not sure how much I need to worry about electrical isolation and proper grounding. The Power Supply ...
0
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2answers
88 views

When using USB and external power, how should I isolate the grounds?

I want to connect USB to my ATmega32U4 microctroller, which is powered by an external power supply. I was thinking it might be possible that the USB +5V/GND would be different than the +5V/GND I am ...
0
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3answers
83 views

Isolated mosfet switching circuit

I have designed the circuit below for a isolated digital output from a mcu. The switching speed is slow -- only 100ms or so. I would like to be able to switch between 3 and 24Vdc at about 1mA to ...
2
votes
2answers
132 views

Low cost UART over fibre

I need to extend an existing 5V UART over fibre for isolation reasons. Digital isolators / optos are no good as I need more isolation than that (0.1pF coupling max. from one side to the other). UART ...
0
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1answer
94 views

Slave can't drive I2C bus low

I'm trying to use an I2C isolator IC (ADuM1251) to isolate one of the slaves on my I2C bus. Without the isolator, the communication works fine. With the isolator, my setup is the following: I'm ...
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2answers
120 views

Eliminate mains common mode ripple from external power supply with poor isolation

I've got a number of battery powered devices which require periodic recharging. I'm using notebook chargers to provide for the input voltage and they work fine... most of the time. Occasionally they ...
0
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1answer
59 views

How do I protect a sensor IC from overvoltage when not in use?

I am attempting to use an IC to monitor the value of an inductor in my circuit. During normal operation a voltage higher than the maximum tolerated value will be present across the inductor. There ...
2
votes
3answers
191 views

Optoisolator with Logic Output - How To Use IC Circuit Example?

I'm looking at an Optoisolator with a Logic Output..It's an optoisolator with a Schmitt Trigger on the output. I think the datasheet is a little bare for my comfort level, so I'm looking for some ...
2
votes
1answer
147 views

Ethernet - 3000V Isolation

I need some means to increase the Hi-pot rating of an Ethernet port to 3000V to meet regulatory approval. The Ethernet controller module is housed in a large metal enclosure and an 18" patch cord ...
1
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1answer
88 views

How can I isolate an rf signal?

I have a rf signal generator (50 ohm, 3.2mw max power, going to be transmitting 13.56mhz. It's a HackRF SDR) , which I want to connect to a homebrew RF power amp. As a newbie to RF design, I know ...
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2answers
201 views

How to isolate two signals from each other if they use the same power source?

See the very simplified schematic down. As what you can see: Two inputs are in the form of a DC signal. We operate each input individually. RL represents a motor. The two inputs are initialized by a ...
1
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1answer
367 views

Measuring an analogue voltage with isolated ground

I am working with a solar EV (car), and I need to measure the throttle pedal signal. The throttle peddle is essentially a 10k ohm pot between 5v and gnd on the motor controller. (0-5V signal). As ...
0
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1answer
56 views

How to properly measure voltage of external supply

What is the proper way to measure an external supply like a 9V battery which is not connected to the controlling part (micro-controller) of the system. Take an external 1-Channel SAR ADC with SPI ...
0
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0answers
118 views

SPI Communication fails with ISO7241C but works with ISO7641FC, same circuit?

Objective: To interface DAC161S997, with Microcontroller C8051F350 through ISO7641FC using SPI Protocol, Which works fine and DAC output is achievable. Now here is the problem, I have changed ...
0
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1answer
36 views

Do I need to place any additional component(s) getween isolated grounds?

Initially I bothered with this question regarding isolated flyback switch mode power supplies. However I'd be happy to investigate this question dipper. So as the output of the power supply is ...
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0answers
55 views

Recommendation for Overvoltage Protection

I am now trying to design an adapter between an inverter and a simulator. I actually need to do some protection for the very expensive simulator on the design. I did my job for digital signals with ...
0
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1answer
37 views

Power Metal Oxide Resistor - Maximum pulse voltage

I am looking for a suitable series resistor (220k) for a 230VAC optocoupler input. The device must meet requirements from EN60664-1. I am still trying to understand the final requirements, but from ...
3
votes
1answer
72 views

Can a FELV circuit be connected to a SELV circuit?

This might be a very very simple question, but I'm unsure how to interpret the rules. I have a circuit which switches 230V using relays. The circuit is a motor controller for a motor control box ...
0
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1answer
62 views

Pulse Supply Ground Reference

I am currently working on a high voltage supply for short (50-100ns), quick (<30ns rise time) pulses. The below circuit is my first rough draft for the power supply, I realized that by connecting ...
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1answer
118 views

Transformerless stabilized power supply for isolation amp

I'm building a circuit similar to this: https://courses.cit.cornell.edu/ee476/FinalProjects/s2008/cj72_xg37/cj72_xg37/ (voltage and current sensing of a 230V line) I'm using two HCPL-7520 isolation ...
0
votes
1answer
173 views

floating ground for AC and DC power supplies

I wanted to connect two power supplies, one is AC (240V , 6A) and the other is DC (3,3V, 300mA). But i read in some referrence that connecting AC and DC power supplies could be dangerous if the two ...
0
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1answer
58 views

Using ADuM3150 for SPI Interface with Arduino

I am trying to use an isolator for SPI communication with the Arduino. I am presently using the ADum3150. You can find the datasheet here. There are some delays associated with this arrangement and ...
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2answers
173 views

Grounding a 30KVA isloation transformer

My company does audio visual services. When we use a single 120/208 VAC Three-phase "Y" power source for lighting, audio and video we get noise caused by the lighting dimmers injected into the audio ...