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

learn more… | top users | synonyms

1
vote
0answers
502 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 ...
2
votes
2answers
148 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
161 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
120 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
144 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
360 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
234 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 ...
3
votes
1answer
215 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
488 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
64 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
323 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
81 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
212 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
288 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
194 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
202 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
108 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
557 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 ...
1
vote
1answer
117 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
240 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
121 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
278 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
551 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
1k 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
398 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
172 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. ...
3
votes
3answers
287 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
172 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). ...
2
votes
1answer
299 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
286 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
1k 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 ...
5
votes
3answers
198 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
447 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
4k 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
490 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
702 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 ...
6
votes
4answers
2k views

how to electrically isolate a PCB from a heat sink

I have a set of LED driving lights on my motorcycle that must be wired through a ground-leg pulse width modulation dimmer. The problem is the mounting bracket for the lights is grounded, so the lamp ...
0
votes
2answers
259 views

How to implement an isolated connection matrix

I need to implement a circuit for a researcher, which looks a little bit like this: Description of the circuit: There are two or more fully isolated biphasic current drivers, and N output pins. ...
1
vote
2answers
499 views

Isolation transformer weirdness

I recently posted a question about cutting the ground wire in an isolation transformer to make it truly isolated. After reading the responses, I decided the best advice was to reconnect the ground ...
5
votes
3answers
1k views

Cutting the ground wire in an isolation transformer?

I bought a non-tech isolation transformer (500w), which I planned to cut the earth mains ground from the output, but leave the chassis grounded; however, when I opened it up I found the output outlets ...
4
votes
3answers
1k views

home brew isolated oscilloscope lead

The ground clip for an oscilloscope lead is normally connected within the instrument to the power supply earth, and there are surprising circumstances where this could matter. The situation is very ...
12
votes
2answers
7k views

What values of resistor and capacitor to use for AVR reset pin isolation?

Background... I'm a newbie to AVR applications. I recently built two ATTINY13-based circuits (glorified LED blinkers) which worked correctly (independently) on the breadboard. When I combined them on ...
5
votes
1answer
845 views

How should I isolate AC and DC on a small PCB?

I am designing a small PCB (1"x1") and it will have some DC logic traces (5V and GND) and some high frequency AC power traces (100V 1000Hz 50mA). Are there any special considerations I need to take ...
1
vote
1answer
617 views

How close can I place two transformers?

I need to place two of these transformers in a case. How close am I allowed to place them? Can they touch each other (of course, they will be electrically isolated)? Is their orientation with ...
5
votes
2answers
1k views

Isolation transformer and scope when troubleshooting SMPS

I have a simple question, when troubleshooting a SMPS is highly adviced to use an Isolation transformer. But my question is this, if im using a scope to troubleshoot the "hot" side of my SMPS, both ...
5
votes
1answer
5k views

Is galvanic isolation of Hi-speed USB impossible?

I have a USB isolator which provides galvanic isolation of a USB device from my PC, but only works for low speed and full speed USB. I can't find any alternative electric isolators which do provide ...
4
votes
1answer
156 views

how to test isolation of DCDC convertor?

I have an isolated DC-DC convertor which boasts a 1.5kV isolation. I have a PCB made along with the additional components it requires. How can I test it?
0
votes
2answers
536 views

Sixteen 100v isolated power supplies

I need to create sixteen isolated power supplies on a single PCB. Input voltage 9v DC. Output voltage 100v DC. Output current 10mA each. No precise regulation needed. Efficiency not terribly ...
3
votes
3answers
345 views

Isolation of watch crystal from ICSP

I'm working on a project which uses a PIC with a 32kHz watch crystal attached to Timer1. Unfortunately, the chip I'm currently using, PIC16F1827, shares the T1OSI & T1OSO pins with ICSPCLK & ...
7
votes
2answers
388 views

Isolation transformer to reduce speaker pop

I have some computer speakers which suffer from the following problem: when switches flip in certain devices in the house, like the thermostat on a radiator or the refrigerator, the speakers will emit ...