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

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3answers
56 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 ...
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2answers
56 views

Charging 2 different age batteries using a battery isolator in my vechicle [closed]

I am interested in using a battery isolator, specifically this battery isolator, in my van to charge a deep cycle auxiliary battery using the vans alternator. I would then like to use that auxiliary ...
2
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1answer
62 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
62 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 ...
0
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2answers
130 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 ...
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1answer
106 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
45 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 ...
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0answers
81 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 ...
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1answer
33 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 ...
0
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0answers
42 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
23 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
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1answer
48 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 ...
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1answer
36 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 ...
1
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1answer
65 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 ...
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1answer
84 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
36 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 ...
0
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0answers
48 views

What parameters are key in selecting a transformer to pass digital data?

Looking to fiddle around with some digital signaling through transformers. Never done, so this is just to experiment and see what it looks like. For the purpose of digital isolation, what types of ...
1
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2answers
84 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 ...
3
votes
1answer
44 views

Purpose of deleting internal PAD

I just learned today that, when you're routing the board you can delete the pad of through hole connectors on the internal layout. Some company even ask to delete all the internal pad that are not ...
0
votes
1answer
62 views

In what order should I isolate and attenuate an audio signal?

I have a cheap bluetooth audio module (with no documentation) that outputs a signal greater than line-level. It was probably designed to be connected directly to small speakers, since the ground on ...
2
votes
2answers
83 views

What are options for an optically-isolated power supply?

I'm considering options for an isolated power supply (1mA @3V) with very low noise pickup and capacitance to mains/ground. Is there a simple optically-isolated solution, preferably using an ...
0
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1answer
85 views

Power regulation and isolation for low current device

I'm looking for a solution to regulate power and provide isolation for a 3.3VDC system. I am using a 5VDC 500mA power supply that needs to be regulated to 3.3VDC with isolation to protect analog ...
2
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2answers
170 views

How much is a transformer's secondary floating?

Consider an isolation transformer with its secondary referenced to ground via a resistance R as in the following picture. simulate this circuit – Schematic created using CircuitLab If R ...
0
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1answer
84 views

Can 0V from an isolated source arc to earth ground?

I have a high voltage bus bar (~300-400VDC) that is powered by a variac. This sits in a case that has other electronics that are powered by a step down transformer (120VAC to 24VAC, then rectified to ...
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2answers
106 views

Understanding to isolating sensor input capacitance

The circuit given above is pH sensor buffer circuit, picture taken from here. This circuit have pH sensor input and gives an output that can be read by multimeter which is U2's OUT_ pin . U1 is here ...
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1answer
86 views

Switching Regulator Ground Moating

I have a DC-DC switching regulator that operates at switching frequency of 260Khz that steps down a 28vdc to 3.3Vdc. On the same PCB I have a microcontroller and would like to have it's ground plane ...
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2answers
100 views

Mains isolation is mandatory for UL/CE/CSA compliance and other certification?

I have a design with a non user accesible low voltage section. Is mandatory to do mains isolation to pass succesfully UL/CE/CSA despite my low voltage section is not accesible for user?
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0answers
25 views

Unregulated Forward Converter for Galvanic Isolation

It seems to me that I could use an unregulated forward converter to provide galvanic isolation and then use a DC-DC converter to provide the voltage regulation. I'd use a two switch forward converter ...
0
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1answer
45 views

Optoisolated Feedback Pin Operation

In the case of galvanically isolated AC to DC converters, a controller IC is used to regulate the output voltage of the converter. The feedback pin is fed a signal from an optoisolator driven by the ...
2
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2answers
132 views

What is the source of leakage current thru an isolation transformer?

I want to use my oscilloscope to check the cleanliness of the output a high-voltage power supply (electrophoresis type, up to 3000 volts DC). I built a 100:1 voltage divider (out of 2 resistors - ...
0
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2answers
94 views

DIY Isolated Power Strip?

Would it not be ok / safe to take a surge protector style power strip, cut the mains cable in the middle (or maybe slice it open and just fish out the load and neutral wires so that the ground wire is ...
0
votes
1answer
54 views

isolation between lcd 20*4 lcd and tm4c123 [closed]

power suply required for my launchpad is 3.3 v and that required for lcd is 5 v. I want to isolate lcd and launchpad. What should I do? do i need to put optoisolator between each pin of lcd and ...
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2answers
80 views

Ground loop noise goes away when heater comes on [closed]

I have a ground loop or something in a stereo wiring. I have 3 stereo's connected all with the same inputs(fanout). One stereo several feet away from the other two has an annoying amount of hum. ...
15
votes
1answer
671 views

Isolated DC/DC Converter - Purpose of Capactor connecting two GNDs?

I've been looking at board mount isolated DC/DC converters to use in an application. I found this rather reasonably priced for my needs. Here is what I'm confused about, what is C103 doing here? Isn't ...
0
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2answers
68 views

FPGA power input isolation

I am working on a design that has at least a dozen FPGA's. In the past I have had an FPGA get damaged by a faulty voltage regulator and short out the supply input to ground.Chasing down which FPGA ...
0
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0answers
103 views

DIY HV Tube Isolation Transformer

I am making a bench top tube power supply from salvaged transformers. I want to make it as safe as possible so I am checking here before the build. The two 120V/20V transformers have electrostatic ...
6
votes
8answers
1k views

Why are we not always isolating the mains supply?

Something struck me: to protect people, the neutral of the supply is connected on the supplier side to Earth, so that leakage through ground is detected when for example someone touches the phase ...
2
votes
1answer
144 views

How do I pick an inductor(s?) for an LC filter on a power rail?

I'm using a TI SN6501 transformer driver to provide an isolated power supply for a project I'm working on. However, it is imperative that the output power rail be as clean and noiseless as possible, ...
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1answer
75 views

Isolation on outputs

To measure a voltage in a (potentially dangerous) external system, people typically use a differential amplifier or even an isolation amplifier, something like this: simulate this circuit ...
1
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1answer
112 views

Is using a transformer at reduced voltage a bad idea?

My Google is failing me. I want to make an isolated AC voltmeter capable of working at 120 or 240 VAC. I've found a suitable 240 volt to 5 volt transformer to use (current capacity doesn't matter - ...
0
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1answer
112 views

Class II isolated power supply (wall wart) — referencing the output to mains neutral?

If you connect the - terminal of a Class II (isolated) wall-wart-type power supply to the neutral of the mains circuit feeding the wall wart, will that cause any damage or hazards that I should be ...
1
vote
4answers
138 views

Low component count isolated contact closure without power on the remote side

Other answers here show a common way to allow a microcontroller to cause a contact closure (button press) within another device in an isolated fashion: use an optoisolator. I have the reverse ...
5
votes
2answers
143 views

Optocouplers for purposes other than galvanic isolation?

In the diagram below there are two modules, A and B, which are separated by a physical distance of about 15m. Module A has a 12V DC power input. Module A powers module B (they share a common ground). ...
0
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1answer
60 views

Using a ferroresonant regulating transformer as an isolation transformer

I'm looking to use a (surplus, NOS) Sola (catalog number 22212) ferroresonant voltage regulating transformer (120V primary and secondary) as a low-power isolation transformer (4A) in case I need to ...
0
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0answers
60 views

Full Speed USB Isolator

Can anyone suggest a way to galvanicaly isolate a USB Full Speed (12Mb/s) signal with a solution height of less than 2mm? Parts like the ADUM3160 (link) and ADUM4160 exist but they are too tall for my ...
3
votes
2answers
148 views

Are IC sockets suitable for mains voltage?

I need to derive a low-voltage galvanically isolated 50 Hz signal from 230 V mains. I'll use an opto-isolator for this. I'd like to use IC sockets for all ICs in this personal one-off project. ...
0
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1answer
82 views

Earth alternative

I'm designing an industrial machine which is AC motor derived. There are sensitive analog sensors (e.g. Load cell) in the system and in the user's site, Unfortunately earth connection is not ...
1
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4answers
235 views

Relay alternatives that are silent and support 500mA+

What can I use as a silent "general-purpose" relay alternative? There are various scenarios where I will need a relay-like device that allows me to control one circuit with a separate isolated ...
2
votes
1answer
102 views

How to decide whether or not to use isolation in a circuit that has a microcontroller and a 48V DC supply?

A potential divider connects a 48V(worst-case) battery supply and a micro-controller for voltage sensing. Is it enough if I take care of the resistor values of the potential divider so as to limit the ...
0
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1answer
108 views

Need to isolate panel meters from each other?

I have a computer power supply I am planning to use for electronics work. I was planning to make a box with voltmeter/ammeter panel meters on each output voltage (3.3V, 5V, 12V, -12V). I have read ...