Questions tagged [safety]

*Your* health and safety while working on electrical devices, and designing devices that will not shock, set fire to, or otherwise harm the user of the device.

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11
votes
1answer
266 views

Is this LED fixture safe for use with its current fabrication?

My father is currently interested in investing into a Ukrainian LED fixture manufacturer, and after he bought home a sample, I'm scared. There are 94 LEDs paired up with diodes, all in series, ...
8
votes
2answers
1k views

Designing electronics and their enclosures for the outdoors

I think the title captures it, but to expand upon this further. What are some of the best practices that you use to place electronics outdoors? Include what you do for the cases and mention issues ...
5
votes
2answers
226 views

grounding connection?

What's the easiest way to connect a ring terminal to the ground terminal of an AC outlet? Are there plugs you can buy that make this easy? I don't need (or want) the line and neutral wires accessible,...
8
votes
3answers
2k views

Which of these approaches for a watchdog timer?

I recently learned about watchdog timers, and am trying to implement one for my circuit for the purpose of resetting my (AVR) microcontroller if it hangs (i.e., doesn't respond to the watchdog). ...
10
votes
2answers
303 views

How to ensure my device is safe for every day use?

I have put together a simple wake up light. It has an external powersupply, at the moment rated 7V and 600mA. Inside it has Arduino and bunch of LEDs controlled by a MOSFET. It works fine at the ...
4
votes
1answer
347 views

DIY Electrical Safety

I'm quite into DIY projects and I am looking at making an electrical unit out of a Raspberry PI and a computer monitor. I was wondering if someone could provide me any information on what I should ...
10
votes
7answers
11k views

How to hook up a mains voltage relay?

This will be my first attempt to control a 110v device (high voltage, by my standards!). Initial tests will be on a table lamp; eventual target may be a small 500W heater. How should I wire the 110V ...
10
votes
2answers
913 views

What is this strange long wire for in a single induction cooking unit?

Tonight I dismantled one of those single induction hobs: Inside there were two PCBs. The incoming mains was wired to the top left PCB, while the other contained all the low voltage components, plus ...
5
votes
3answers
167 views

Running router out of its case

I'm currently building a robot, and as part of its spec it must connect to a wifi network. I have a Belkin wireless router, which I have taken out of its case to expose the PCB. My question is: Is ...
6
votes
2answers
1k views

Disassembling a camera - dealing with a flash capacitor

I'm disassembling a broken old camera (an Olympus FE-110) and I've learned that I should be really careful with the capacitor inside. I wanted to follow the guide linked at the bottom of this article, ...
1
vote
2answers
342 views

Reflow oven AC cable splicing insulation and thermocouple readings

I'm building a reflow oven. I know what I'm doing, I just want to verify my plans to make sure I'm not doing anything stupid before I start. The idea is to have an arduino (powered externally) ...
0
votes
3answers
5k views

What condition may cause the plug or the power adapter to become very warm or hot? [closed]

I know that using a power adapter for very long hours (probably more than 24 hours) can cause the plug of a power adapter (or even the power adapter itself) very warm or hot. However, I am interested ...
2
votes
1answer
158 views

Are dual MOSFET devices isolated from each other? If so, to what degree?

I am using an OnSemi NTGD3148N dual MOSFET in a project. I cannot find a specification anywhere in the datasheet stating the isolation between the devices; and this holds true for most dual MOSFETs ...
4
votes
2answers
748 views

Circuit safety -> Preventing smoke through accidental connection of battery voltages

I'm building a circuit whereby users are able to connect their battery to the pcb which will then be sampled by a micrcontroller. Voltage divider circuitry is all good so please don't focus you ...
6
votes
1answer
901 views

Very small scale electronic goods manufacturing regulations

I would like to make a 12v rechargeable battery operated robotic toy, for sale as a kit. This would be more of a hobby for me, selling say 5 units a month with a very small turnover. It would just ...
6
votes
1answer
4k views

Safety precautions working with high voltages (Nixie Clock)

I'm building a nixie clock kit with these instructions. I'm up to the part where I have to test (page 17) the high voltage components (the power supply is 12V 250 mA) which is up to 170 volts (page 5)...
0
votes
1answer
223 views

Is connecting a 2 A adapter to a 1.3 A electrical device safe? [closed]

Is connecting a higher-amp (e.g. 2 A) adapter to a lower-amp (e.g. 1.3 A) electrical device safe? I wonder if it will cause the adapter to over heat and cause fire or cause damage to the electrical ...
2
votes
2answers
611 views

Replacing analog scope BNC input connectors

I am wondering if it's safe to replace the BNC input connectors on my old Hitachi v-422 scope. As long as I'm careful and stay away from the CRT etc? Or is there anything else I'm not aware of?
3
votes
3answers
10k views

Safety Equipment and Precautions for DC Circuit Experimentation and Development

What safety equipment and precautions should I use when learning about, experimenting with, and analyzing DC circuits? I have a power supply capable of 32V@5A and 16V@10A (which supports selectable ...
7
votes
2answers
9k views

Safe to add a switch into power cord?

First off: I realize that my problem could be solved by simply using a few power strips with built in on/off switches, but I do not want to do that. I look at this project as being a learning ...
9
votes
4answers
4k views

Moving PIR sensor (or IR camera), aka Predator like alien scanner

To avoid public transport and the car, I decided to go to work on foot everyday but I have to pass a small, but dark (in the evening) and scaring wood. Even if I use flashlights, I'd like to have a ...
7
votes
3answers
4k views

Cooper Bussmann's screw-in Edison-base mini breakers aren't for inductive loads. What does “inductive” mean?

I'm thinking of buying some Edison-base screw-in miniature circuit breakers to replace some of the fuses in my house. There are some made by Connecticut Electric and some made by Cooper Bussmann. ...
5
votes
1answer
4k views

AC->DC supply, how to deal with chassis ground being connected to digital ground?

I have an external triple-output AC-DC supply with the following output pinout: On the power supply, "ground" (pin 2) is internally connected to the ground wire of the mains plug. I'll refer to it as ...
5
votes
2answers
581 views

What are some cheap, reliable methods of water-proofing switches and buttons?

I'm working on a project to put together a custom bike light from some LED flashers and a battery pack. I'm looking at two different options, one which comes with a built-in switch, and another where ...
14
votes
2answers
23k views

Is it safe to disassemble an unpowered PC power supply?

Once a typical PC power is unplugged, is there any danger of receiving a shock while disassembling it? Are there typically high voltages stored that one should be aware of? context: removing a ...
0
votes
2answers
2k views

Dual polarity power supply for project, possible choices?

For a variable power supply I require 15V to get ~0-12V, and +/-15V for an op amp as part of the project requirements, also negative rail in the future. Two plugpacks (isolated, 15/0/-15)to me seems ...
2
votes
1answer
4k views

Putting two wall-warts in series?

I'm helping a friend make a 48 inch hot-wire foam cutter. He would like it to be as economical as possible, so I'm giving him two 15V 1.1A wall wart power supplies that I have sitting around. I don't ...
6
votes
2answers
5k views

In i.e. a TO-220 package, why is mounting the (pin connected) tab to case safe?

All the time I hear that the tab on a TO-220 like package is electrically connected to the centre pin, for example "out" on voltage regulators. Does mounting them to a heatsink (of which may come in ...
14
votes
12answers
2k views

What Workbench Safety Improvements Have You Made?

What was your worst electronics workbench accident involving equipment, voltage, soldering irons, chemicals, or whatever else, and what changes have you made to prevent that type of accident from ...
3
votes
2answers
4k views

Why is it safe to touch the chassis of a tube amplifier and something earth grounded simoultaneously?

I'm hoping this is not too much, originally thought it would be a simple question, but the more I thought about the matter, the more I could see this wouldn't happen. If it's too much I hope some of ...
0
votes
3answers
2k views

Issues with resistor heating, for an LED?

I am direly confused on this. I've used 220 Ohm resistors in the past for all of my LEDs (at least that I can remember), however nothing on my arduino+breadboard with a few leds on the 5V breadboard ...
7
votes
1answer
150 views

How should unidentifiable breakers and fuses be represented in arc flash studies?

When analyzing arc flash hazards in industrial power systems, I have encountered situations in which visual inspection reveals the manufacturer and the trip rating only. The breaker or fuse model ...
3
votes
3answers
957 views

Static dissipative ESD footware

Are shoes like this used in professional labs or is this just a gimmick? http://www.esdshoe.com/products/Lightweight-Classic-Mid-High-ESD-Composite--Basketball-Shoe-%252d-Men%27s.html
19
votes
13answers
4k views

Path for a child to learn electrical engineering

What are some paths for a child (7-year-old) to learn electrical engineering (in a safe way)? I do not want to saturate (or frighten away) the child with lots of concepts, I want that my son learn ...
2
votes
1answer
2k views

Safe operating area for different types of battery chemistry?

I'm trying to find the safe operating area for various types of batteries; in particular I need minimum and maximum termination voltages, although information on temperature / power / current is also ...
2
votes
3answers
2k views

Are solenoids/inductors dangerous to have exposed?

An inductor doubtfully will be in a position to be of harm, however a solenoid with 1A+ running through it (and of course a lot of it stored in the magnetic field) can certainly harm the circuit, if ...
7
votes
3answers
3k views

Decomposing Kinect Laser Projector - Is it really safe?

I am looking at Kinect Laser and couple of things that are not clear, so I thought I bring up here. First the known facts: - Kinect has a laser projector that works at 840nm - Output power of the ...
5
votes
2answers
2k views

Chassis + Ground Safety

Why is it safer for ground to be connected to the chassis for an electronic system? For example, the ground on the mains supply of an AC motor in a box fan is connected to the outer chassis of the ...
4
votes
3answers
512 views

Is there a wiring design that would protect a person in bath from electrocution when a powered appliance is dropped?

Hairdryer falling into bath is a Hollywood cliche already. Jokes aside, is there a wiring design that would protect a person in this case? Overcurrent protection will trip too late, residual current ...
3
votes
2answers
869 views

How to properly isolate multiple power supplies

Say you have a single 110V AC supply and need to use it for a number of devices, each requiring very different characterists. For me personally these are: a direct use of the 110V AC supply for a ...
7
votes
3answers
2k views

Why is power supply from electrical utility referenced to earth?

In response to the question Basic Training for working with 120V AC zebonaut had replied that "A regular wall outlet is referenced to earth" and this provides the close loop for the circuit to ...
7
votes
8answers
2k views

Basic Training for working with 120V AC

I'm planning to build a digitally-controlled light dimmer circuit. I'm not trained in electrical engineering, and I don't want to do something that an electrician would immediately recognize as ...
1
vote
1answer
259 views

relationship between temperture, current, thickness, and material

I used lan cable for light LED up on my bread board power source is PC's power supply. without any resistor, the lan cable melt! I reallize I have to keep OHM's law in my mind and use proper ...
3
votes
2answers
245 views

cable jacket melts

I am new to hardware. My breadboard just arrived and I am trying to light up my LED. I used computer power supply for power (red wire for + black for -) and used strands of LAN cable for connect LED ...
3
votes
3answers
3k views

Any problems with “floating” an oscilloscope?

I have a Chinese scope with a two-pin power cord and a plastic body, and measure megaohms between its ground terminals and the actual earth, so I believe it has an internal isolation transformer (I ...
0
votes
2answers
355 views

Safe to open old sony remote?

I have an old sony universal remote, the rm-v15. I opened it to get to the pcb, and a strange nasty smell came out of it. Is there anything I should be worried about? Any hazards used in old remotes?
12
votes
3answers
6k views

Extra negative battery cable when charging outside car?

If you go to: http://www.battery-chargers.com/charging_instructions.htm ...Under "Operating Instructions" part "B: Charging battery outside of vehicle", it says you have to attach an extra jumper ...
2
votes
3answers
2k views

Switching 120V AC with Digital Logic on Isolated Power Supply

Context: A digital phase-controlled light dimmer system. 120V AC mains I use an isolating transformer (and rectifying circuit) to generate +12V and +5V DC rails. I want to use reverse phase control (...
16
votes
9answers
5k views

Safety of making PCBs

I've been making a few hobbyist PCBs at home and note that the photoresist developer and ferric chloride etch solutions are both pretty nasty chemicals that come with all kinds of warnings. So I've ...