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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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13
votes
1answer
2k views

Can Arduino operate under water?

I have an idea for an automated small toyish submarine. Can I use the Arduino for this? Does it behave well under the ocean surface? I think I'll need some kind of casing with silicone around it, and ...
13
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2answers
994 views

How to rinse container used for ferric chloride etching?

From what I have gathered online, after etching one stores the "used" ferric chloride (more specifically FeCl2 and CuCl) in some container which can then be taken to a waste disposal facility. What ...
13
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1answer
841 views

Safety when experimenting with large currents

I am experimenting with large currents from ultra capacitor discharge. For example with 500 A (at 2.8 V) you get a very impressive demonstration of the magnetic field of a straight conductor using ...
13
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4answers
4k views

Solder Fumes - Activated Charcoal vs Outside Venting

Like probably everyone else here I do a ton of soldering. When I setup my current workshop I built a fume extractor that actually goes in a window near my bench. Basically just a length of dryer duct ...
12
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6answers
4k views

What makes mains voltage safe in homes?

When I started learning about electrical engineering, one of the most important safety guidelines that I learned was that voltages over 36V can be dangerous. As my circuits professor put it, 120VAC ...
12
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5answers
1k views

Safety of Villard cascade

My teenage son has been building Cockcroft-Walton multipliers in his spare time lately, and I'm potentially a little concerned in case he electrocutes himself. His circuit is powered by 4 AA cells in ...
12
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6answers
4k views

How To Know If a Fuse Will Work Properly?

I want to know what kind of periodic test we use to test if a current-limiting fuse will normaly open and protect an electronic circuit (a battery charger) if a failure occur (short circuit or over ...
12
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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 ...
11
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3answers
3k views

Making a device explosion proof

I am working on prototyping a gas leak detector device to be used in homes, it should have two small windows in the casing to allow sound to go out and the other window allows gas to reach the sensor. ...
11
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3answers
1k views

How do I protect myself when testing a PCB that involves an AC line?

I have to test prototype PCBs that convert household AC into several DC voltage levels. I concern about my safety when working with AC and would like to know how to properly setup a testbench that, ...
11
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6answers
32k views

Is hot glue a good insulator?

I need to mount some relays that I have soldered wires to. If I place them on a non-conductive surface and use a generous amount of standard glue from a hot glue gun, will that be relatively safe? I'...
11
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5answers
15k views

Disposal of ferric chloride etchant

I've just got hold of a nice little PCB etching kit, which uses ferric chloride as the etchant. I know it's re-usable for at least a few etches (though the kit doesn't actually specify an estimated re-...
11
votes
1answer
267 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, ...
10
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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
3answers
14k views

Mechanically damaged capacitor leaked liquid - is it toxic?

I have mechanically damaged a capacitor on an old motherboard and it made a PFFFT sound like some gas went out of it and then some liquid leaked. What is that? Is it toxic? I hope that it was not ...
10
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7answers
5k views

Mains Voltage on Strip Board

I need to prototype something quickly as a proof of concept. Is it safe to use mains (UK 230V) on stripboard? It will be going to a transformer so I can control some appliance. Or should I design a ...
10
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4answers
58k views

Calculating current load for a switch?

This SPST switch is labelled on the box as "Rated 10A at 125VAC or 6A at 250VAC". Is there a calculation as to the amperage it will handle at 12V DC? (update) As JYelton points out, a naive ...
10
votes
2answers
5k views

will a circuit breaker designed for 230VAC work for 12VDC?

Will a standard home automatic circuit breaker, designed and sold as to work on 230V AC (alternating current), and for example 16A, or 25A etc, will it work (break the circuit if it exceeds the rated ...
10
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2answers
7k views

How do these safety relays work?

I've been trying to understand how these safety relays from Weidmuller work. But since I can't find any useful resource on the internet, it has remained unclear for me. Here is the link to data sheet: ...
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 ...
10
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2answers
915 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 ...
10
votes
1answer
242 views

Connect two different sources with two Digital Ouptuts using an Adam 4055

I would like to operate an Adam 4055 module to control two different applications having their own power supply. Adam 4055 is Digital Input/Output control module over RS-485, I use only the DO part ...
10
votes
2answers
7k views

What is the recommended way to protect a circuit from non-transient overvoltage?

I'm designing a 12V battery-operated portable lighting controller, and frequently am asked about improving the run time. The simplest way is to add a second battery in parallel, but I often worry that ...
9
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6answers
4k views

Why aren't starter circuits protected?

In most cars and trucks, a thick cable connects the battery directly to the starter (solenoid). Why don't these circuits have have any kind of overcurrent protection? It is an accepted practice ...
9
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8answers
7k views

Is it safe to use a DC power adapter that isn't UL Listed or CSA certified?

I picked up a 9V switching DC adapter from SparkFun a while back, but I've been hesitant to use it because it doesn't have any of the usual "safety" approvals that you normally see on power adapters (...
9
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3answers
9k views

ICs with humidity or moisture sensitivity - bake recommendations

I purchased some ICs recently that included something I'd not seen before - a moisture 'sensor' on a paper strip with color indicators for a few specific levels of humidity. Once the paper reaches a ...
9
votes
4answers
12k views

Which are the safety recommendations for soldering?

I was reading about tin alloys for electronics soldering and found it it has about 40% of lead in composition. Lead, everyone knows, it's very dangerous to breathe due to being a heavy metal. Also, I ...
9
votes
3answers
380 views

Is it safe to treat a system downstream of a reverse-biased diode as de-energized?

Suppose I have a 480 VAC line, feeding a rectifier and filter caps. Obviously this is not something to be trifled with while live. Now, suppose there are blocking diodes coming off the DC bus, as ...
9
votes
3answers
5k views

How do I “cap” a wire so it doesn't short or electrocute someone?

I'm repurposing a PSU that I recently replaced. I'm using it in a project that needs high current supplied. I don't need all the wires (as you could imagine), but I don't know how to seal them off ...
9
votes
2answers
14k views

How to attach (safely?) an o-scope to various sources

I've heard of course that probing mains can ruin your oscilloscope, so that is out of the picture. There are a few situations I do not quite understand however: Is probing an i.e. 10:1 transformer ...
9
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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 ...
8
votes
4answers
2k views

What is the identity of this shiny insulator?

fig: Shiny layer I've seen many times, on metallic objects, a kind of insulator layer is given (I've tested its resistance with multimeter and it shows infinite ohms). The layer is greenish-gold in ...
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). ...
8
votes
4answers
87k views

What's the advantage of 'electrical tape' over 'regular' adhesive tape?

For covering copper wire and the like (whether it is carrying current or not), what's the advantage of applying electrical tape as opposed to 'normal' consumer adhesive tape (of similar thickness? ...
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 ...
8
votes
6answers
4k views

How dangerous are disconnected bulging batteries?

It is well understood that if you have a device that uses a Lithium-Ion battery, and if the battery starts to bulge, then something is wrong with the battery and you should properly dispose of it by ...
8
votes
1answer
317 views

Is it possible to test a lithium ion battery for safety? How?

There have been stories in the news recently about fires that are believed to be caused by the lithium-ion batteries inside hoverboards. If you had one of these devices and didn't mind taking the ...
8
votes
3answers
6k views

How can I safely connect both Arduino and a 120V 10A circuit?

I'm building a thermostat, and the idea is to have it fire one of two 120V 10A circuits (one to heat, one to cool). I have two of these modules for the relay and I ...
8
votes
1answer
2k views

Why are fast blow fuses more tolerant to small over currents than slow blow fuses?

I am looking at fuses from a cable protection standpoint. According to this doc the IEC standards for typical miniature fuses (IEC127-2) can be summarised as: Why can fast acting fuses tolerate a 210%...
8
votes
2answers
162 views

Is the maximum audible noise from power supplies regulated in Europe?

Power supplies make sometimes a lot noise in the range of kHz. Is there a regulation for the maximum allowed noise emission for consumer electronics on the European market? Is there a regulation ...
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 ...
7
votes
4answers
7k views

Is it Safe to Plug an Extension Cord Into a Power Strip? [closed]

Just a bit of context, I am a technology enthusiast. I love everything from software to hardware, Windows to Linux, Computer to Phone, and everything in between. So, I wouldn't be surprised is my ...
7
votes
5answers
13k views

Can a charged 120v high voltage capacitor really kill you? [duplicate]

recently I have been hacking few psu and have to deal with some high voltage caps. It sort of scared me, but thinking about it, what is the chance of it really killing me. Is it safe to touch one ...
7
votes
4answers
7k views

Conductive Lubricant for Connectors?

I'm making a safety disconnect for an experimental RC craft. It will be tethered to the ground, and if it goes out of control the tether will pull a plug disconnecting the power. I will make the ...
7
votes
6answers
45k views

Is it safe to run and charge a deep cycle battery in an enclosed space like a bedroom?

I'd like to experiment with running a small server (5.5 watts) / 85AH deep cycle battery / charged via 30 watt solar panel from my bedroom. I generally keep the window open, but want to make sure it'...
7
votes
3answers
4k views

What is the difference between “medical” grade and ordinary AC-DC power supplies?

Background My wife and I are expecting a baby soon and a family member has given us their previously-used, thoroughly cleaned electric breast pump. The pump came from the vendor with a "medical grade"...
7
votes
2answers
1k views

Why are typically fatal currents non-lethal when they pass through your body for a short time?

I've been reading up on electrical safety, and the commonly cited controversial quote "it's not the volts that kills you, it's the amps". What I have gotten out of these sources is that it is in fact ...
7
votes
2answers
688 views

Microcontroller's watchdog

Can anyone explain a little more about watchdogs, specifically in the circuitry level? If there is some kind of problem in the chip, how can I guarantee that it will be kept running? It is ...
7
votes
4answers
560 views

Building a power supply, want to stay alive

I am building a power supply for a very old laptop. The circuit uses a transformer (220 V primary to 15 V secondary, 33 VA) and that worries me a little. (Please note that I an enthusiast and so far I ...
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. ...