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

learn more… | top users | synonyms

0
votes
0answers
40 views

Isolation for loop powered devices with limited power

I am implementing 4~20mA Transmitter that consist of a MCU, a current DAC, and an ADC for measuring an analog signal. I would like to electrically isolate the analog signal from the loop current so ...
0
votes
1answer
40 views

Should AC voltage supplied to an external device through a relay be electrically isolated from the main power source of the enclosure?

Given a power supply in an electrical enclosure powered by 120 VAC. An I/O device will trigger a relay with a 24 VDC control. The signal from the I/O device will enable the relay for a set duration. ...
8
votes
3answers
579 views

Are there any disadvantages using magnetic couplers instead of opto-couplers?

I'm trying to find the disadvantages of using magnetic couplers versus opto couplers (1). I'm deciding which of the two I should use to create a galvanic isolation between two PCB's that are going to ...
1
vote
1answer
78 views

What is this Circuit's function? Does it involve Isolation?

My question is: Does this circuit isolate the "X Volts" lines from ground (1) If not, how should I implement an opto-coupler to provide isolation between the data lines ("X Volts") and ground? ...
2
votes
1answer
84 views

How to work out or calculate this circuit?

I'm not an engineer, I understand a lot but I fail to understand how it works and how to calculate this for a 24vdc input:
0
votes
2answers
80 views

Isolation of CAN-High and CAN-Low signals [closed]

I have to isolate the signals CAN-High and CAN-Low on a CAN bus. Is there an isolated CAN repeater (something like IXXAT's CAN-Repeater - 110 × 75 × 22 mm) which would be ...
11
votes
2answers
831 views

Why AC points on PCB are separated by a hole

I want to find out why, in professional PCB's, they separate between the AC (220 VAC) points on the PCB with a hole in the PCB: Is it for more isolation between the AC lines? Is leaving a distance ...
2
votes
3answers
131 views

I2C isolation; 3kV

I am working on a high-side current sensor, where the high-side is around 3kV. I have come to the conclusion, with some help from you kind folks, that it is best that I float the majority of my ...
1
vote
0answers
84 views

How to isolate DS2406 switch from mains? [closed]

I would like to use a DS2406 1-wire control chip to switch a mains load. Isolation is required and I would like to use the 1-wire supply. There are no power supply at the remote end, only 1-wire ...
1
vote
4answers
134 views

Powering an AMC1200 Isolation Amp

I need to measure a very small current at the high-side of a circuit. The high side is at 3000VDC. The measurement needs to ultimately be in the form of a signal with a peak of no more than 5V, so ...
3
votes
1answer
90 views

Proper power design for a USB device

I'm designing a USB device that I want to be powered eintirely from a wall wart and have a couple questions concerning the power connections and ground loops. 1) If I connect the USB GND pin to ...
2
votes
1answer
116 views

Why DisplayPort cables must isolate the power pin?

I've been investigating why my 2560×1440 DisplayPort monitor and my mini-DisplayPort MacBook Air don't play along, and, it turns out, this is likely due to a wire in the cable that connects the two ...
1
vote
2answers
86 views

Isolate wires soldered on PCB

I'm soldering some cables on a PCB. They are are stranded, so I've first apply a bit of soldering on them and then solder them on my pcb. The problem is, there's on some a bit of exposed copper on ...
1
vote
1answer
75 views

How can I isolate a servo in this circuit [closed]

I have a PIC which I am using to control a servo, I have a 5v supply for the PIC. I wish to isolate the servo from the PIC as the noise the servo creates can cause the PIC to malfunction. NOTE: I only ...
1
vote
0answers
298 views

Can You Drive Back-To-Back MOSFETs (aka a Solid State Relay) Without Using An Optocoupler?

I was wondering if there was any way of driving back-to-back MOSFETs (with their sources and gates tied together as shown in the following image) without using an optocoupler? The reason is that ...
1
vote
2answers
84 views

What is a reasonable isolation voltage for an optocoupler/digital isolator?

I need to isolate an input from my processor. What is a reasonable isolation voltage to look for optocoupler/digital isolator? I've pretty much decided to go with an RF isolator at this point because ...
0
votes
3answers
104 views

What is the reason to use an isolation amplifier?

In a work place PC has a data acquisition card which is 16 bit and has 16 single ended channels. One of the channels is outputting a constant DC voltage which can be controlled by a user via a ...
0
votes
2answers
99 views

How do I leave electrical connection of heat-sink body?

I usually see that some heat-sinks have thick pins to solder on the PCB, and I'm going to use one of them. Since they are going to be soldered on the PCB, the question rises in my mind about their ...
3
votes
1answer
83 views

AC leaks to laptop, cellphone surface. Feel by finger! [closed]

I've accidentaly discovered that several mains+battery-powered devices with metallic casing like cellphones, laptops and mp3 players, exhibit a special kind of friction when stroked with a finger. But ...
4
votes
2answers
238 views

Where to connect shield and ferrites in PCB with isolated planes

I have a device which has two sections of the PCB completely isolated form each other, but connected by an isolator IC (PN: ????). I think I need to shield the whole device for reducing EMI because ...
3
votes
3answers
119 views

What is the electrical connection of heatsink plate of PB case bridge rectifier packages?

I'm going to use two PB-case bridge rectifiers of a certain product in my circuit. I need to know the electrical connection of its heat-sink plate (i.e.; to what pin it is connected to, or if it is ...
2
votes
1answer
117 views

Are the non-metallic colored heat sinks of transistor packages electrically isolated/nonconductive?

When I look at transistor packages, I see two different heat sink types. One type is in metallic color, the other type is black plastic colored. I read datasheets of some components, none of them ...
2
votes
2answers
237 views

How to protect a signal from output short circuit?

I have made a signal generator based on DDS and amplified its output to 0-20 V pk-pk. Now I want to prepare the output side. My main concern is short circuit protection to prevent damage to my device. ...
0
votes
1answer
46 views

Looking for a medium power optocoupler

I have a project where I will control a 3 or 6 watt UV lamp DC with a microcontroller. I want to power my lamps with a AC/DC circuit and switch them on and off with a optocoupler, mainly because ...
0
votes
1answer
164 views

RS232 and RS422 (Isolated and ESD Protected)

I want my RS232 and RS422 to be galvanically isolated and ESD protected. I have two options to implement this requirement. Option 1: MCU-->OPTO-->DRIVER-->ESD PROTECTION Use MAX3232 for RS232 ...
2
votes
0answers
64 views

What are the differences between Channel-to-Ground & Channel-to-Channel isolation?

I have the following questions regarding different types of isolation techniques: What are the major differences between Channel-to-Ground & Channel-to-Channel isolation techniques? Are all ...
8
votes
2answers
187 views

If I put multiple isolated DC/DC converters in series, can I add their isolation voltages?

Suppose I have a DC/DC converter that's rated for 2250VDC isolation for one minute. If I put two of these devices in series, making sure to maintain proper clearances on my PCB, do I get an effective ...
4
votes
1answer
169 views

How do AC and DC hipot tests compare?

Suppose I have a DC/DC converter, Recom RPP30 for an example to hand. It lists an isolation voltage of 3000 VDC. How does this translate to an AC isolation voltage? Would this be equivalent to 3000 ...
0
votes
1answer
110 views

Isolated closing contact other than relay?

I need an isolated closing contact, like a relay, but ideally solid state. Rating 24V 100 mA on the contact side would be plenty. 1 kHz operation would be enough as well. I will drive this from 5V 25 ...
2
votes
2answers
158 views

Turning off a controller in multi chip pcb

I have a design question: How to safely turn off a controller IC's (CC2533, RTC clock) while other (eg. Atmega8) are running ? Basically to program the atmega without pulling it out of PCB. Is ...
0
votes
0answers
70 views

Isolating Probe from stray voltage

I have a PH Probe taking readings from an ungrounded container that has sources of electrical noise (AC Pumps, AC heaters, etc). I would like to protect the probe from that noise. If the ...
0
votes
0answers
300 views

RS232 Ground-Loop Isolation: “creative” solution?

I have a RS232 connection that seem to suffer from different ground potentials at the two ends of the connection: The receiver signals a "break condition" in Realterm. As I understand it this means ...
2
votes
0answers
81 views

Ground coupling a high voltage source with the A_GND and D_GND

I have a device that measures the current in the mains through a 0.01 Ohm 20W shunt resistor. The voltage across the shunt is amplified by a op amp and feed into a uC's ADC for farther calculations. ...
2
votes
1answer
120 views

How do I (optimally) connect Elk-924 (high sensitivity relay board ) to DSC PGM output (sinks to ground)

This sounds like a very specific question, but I think it boils to a generic one -- not at all specific to this equipment. But it will take a bit of backstory to get there. My background, btw, is ...
2
votes
0answers
81 views

Isolation between cells for battery charging & testing

I want to charge Lipo battery packs and possibly other chemistries too. Six cell packs for starters. But hope to handle more and less. Perhaps a lot more cells. For electric vehicles, skateboards, ...
4
votes
2answers
197 views

When is it appropriate to galvanically isolate components/subsytems?

As the question implies, how do you determine when it is appropriate to galvanically isolate parts of the same electrical system from one another? For example, I'm currently constructing a tube ...
2
votes
0answers
305 views

How to isolate low voltage control circuit from high voltage power circuit?

Can anyone give me a brief run-down of some methods I could use for this? I want to drive a MOSFET or BJT with a 12v 555 circuit or oscillator. The MOSFET will drive a high voltage circuit that ...
0
votes
1answer
535 views

Effect of an isolation transformer on leakage current

How do isolation transformers affect the leakage current through protective earth in a system? Scenario 1: Mains is directly connected to circuit. Metal enclosure has a protective earth connection ...
3
votes
3answers
261 views

Mains triac safety circuit design

I am investigating using a triac instead of a relay to control 250V 10A devices. However all the 600V 16A triacs come in TO-220 packages. According to AS/NZS 3100 and AS/NZS 60335.1 I need at least ...
2
votes
1answer
95 views

How can I isolate a power well to reduce noise

I am designing a digital board which will drive a very coarse (simple on-off) high[er] current speaker. I am worried that the switching of the speaker will cause noise in the power supply driving it. ...
2
votes
3answers
179 views

DC-DC isolation for my car stereo… Where do I start?

I recently noticed that my jeep's stereo whines with a frequency that seems proportional to the rpm of my engine (and alternator), and is louder when my headlights are on. If my stereo was powered ...
1
vote
2answers
130 views

Dirt cheap 3-12v DC/DC isolatior chip?

I'm creating a box that will have an external TTL trigger. I want to isolate my box's power/ground from that of the triggering device. Obviously, an optoisolator is the way to go (eg. PS2502). ...
1
vote
1answer
272 views

GPIO input connected to garage door button

I know there are other GPIO / Garage door related questions, but this is not a duplicate- I need to read the status of the garage door button, not a garage door sensor. I would like to connect the ...
3
votes
1answer
198 views

USB + Power: Isolate or not?

I am working on an adapter that will allow a device to be connected to both a PC and external power supply. I am wondering if I will need to isolate the 2 5V supplies with a DC/DC converter and some ...
2
votes
2answers
625 views

How can I do A/D conversion with isolation?

I have to sense a voltage range of 0-25V dc and send to the ATMEGA 32 microcontroller. I want to use a voltage divider for sensing the voltage. But the problem is isolation is required between the ...
4
votes
3answers
162 views

Digital Isolation comparison

I am currently using ADuM4160 by Analog Devices as a USB isolator. However, this part is EXPENSIVE. I was wondering if anyone thinks it can be replaced with ADuM2200. Any reason why this wouldn't ...
4
votes
3answers
336 views

Why are the pins on the official arduino motor shield so long?

Here is the Official Motor sheild website. The shield has pin connectors at the bottom that are 2x longer than on any other shield I've seen. Why is that?
12
votes
3answers
2k views

Cellphone charger has no transformer?

I opened up a really tiny mobile phone charger I have, to see how it is designed. The entire "charger" is integrated into a small 2-pin mains plug, 1 x 1.25 x 0.5 inch, that has an USB socket for the ...
5
votes
1answer
273 views

Determining if a power supply is isolated?

I've been looking for a low cost adapter I can use to power some electronic circuits I'm playing with. Pretty much the only requirement I have at this time is that the adapter is mains isolated for my ...
3
votes
4answers
449 views

Measuring voltage while maintaining isolation

I'm building a variable power supply, and want to provide the ability to digitally measure the outputted voltage and current. The digital power supply used to drive the ADC, microcontroller and ...