*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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1answer
65 views

Guidelines for using an unenclosed power supply?

What are the basic guidelines for safely using a "bare" unenclosed power supply (random example)? As a relative novice, my thoughts are: Definitely need a separate enclosure To avoid overheating, ...
-2
votes
1answer
68 views

Fumes from soldering [duplicate]

I breathe alot of soldering fumes and i don't have anything that is used to remove this fumes while soldering, is it really bad for my health? How it affects the brain and other organs?
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2answers
37 views

Li-ion swappable 18650 in parallel - preventing mixing charged&discharged cells

I'm designing a device that has 6 18650 elements (all parallel) in holders, made so that the end user will be able to pop out the batteries when they're discharged and plug in a set of new batteries. ...
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1answer
66 views

Are Faston tabs safe for earth grounding?

I am having a discussion with coworkers about sufficient grounding to a chassis... my opinion is that a toothed ring terminal in contact with bare metal is required, e.g. Molex 19074-0025, so that the ...
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4answers
85 views

Short circuit when probing live ATX power supply primary section with voltmeter [closed]

I was probing around an old ATX PSU to inspect voltage levels in the primary section. The first 15 minutes went smooth (bridge rectifier inputs, big caps, Power IC Vcc, etc..) but as soon as I probed ...
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0answers
1k views

Got shocked by a native dell laptop charger outputting 19.5 V 6.5 A DC. It was REALLY uncomfortable, but was that dangerous? [migrated]

Okay. My laptop was running out of battery. I grabbed my charger (outputting 19.5 V 6.5 A DC) which was plugged into the wall, and as I touched the end of the charger I got some electric shock going ...
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votes
1answer
42 views

Safest way to hook a 12V wall plug into a hot/ground source [closed]

I have no outlets in a room, but have a box that looks like it converts the 120V source into 12V as well as the 120V source. I need to get power to this adapter shown below, but am wondering what's ...
0
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1answer
52 views

active bleeder circuit for capacitor discharge

I have a circuit with a large capacitor, a solenoid and an N-channel FET fed by a 60VDC supply. When I trigger the FET the capacitor discharge activates the solenoid. This all works as expected ...
0
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1answer
156 views

220 AC to 220 DC Converter

I am designing a circuit that will give me an adjustable 220DC voltage. The load is approximately 2kohms, so the maximum current that will flow is 100mA.And I have design restrictions, it needs to be ...
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0answers
38 views

Is this bell circuit safe? [migrated]

I have an old-fashioned doorbell (like this one: https://upload.wikimedia.org/wikipedia/commons/c/c1/DoorBell_001.jpg) Is it safe to connect it directly to a power supply (I am using a ac/dc ...
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votes
3answers
288 views

How can I test a wire for small holes?

I have stripped one wire, the black/hot/positive one, for a 120v appliance. I had to cut away the outer plastic that surrouneds all three wires, and now I'm afraid I may have nicked a small hole into ...
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3answers
123 views

Safety when using ATX power supply as benchtop supply

I found many pages where people convert an ATX power supply to a benchtop power supply to give 12, 5, 3.3V. However the current output can be very high (several amps). When using this and you NEED ...
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3answers
89 views

Recommended capacitor rating for this mains zero-crossing detector

I found this zero-crossing detecting circuit here I want to recreate it, using the parts that I have on hand (or can get cheapest), but I'm not sure how to choose the correct 0.1uF capacitors. ...
3
votes
2answers
97 views

Isolation transformer and AC potential between grounds

Wisely (I think) after connecting my DUT (Tektronix 2710 Spectrum Analyzer) to an isolation transformer, I measured AC voltage between the DUT chassis ground and my scope (Tektronix 2440) ground lead. ...
2
votes
3answers
103 views

Why is it safer to place a switch on the positive side of a voltage source?

According to the research I've done, it is safer to place a switch on the positive side of a voltage source: http://www.allaboutcircuits.com/textbook/direct-current/chpt-3/safe-practices/ This ...
7
votes
1answer
177 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 ...
1
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3answers
99 views

Contradictions in conductivity

I mostly know how electricity flows but cannot understand some aspects, and have three examples that I cannot fathom: The pilot lighting electrode wire on my house central heating water heater ...
1
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2answers
92 views

Should Class I electric devices be connected to unearthed sockets?

I rent an old house and most of the power sockets do not have earth/ground. I need to connect Class I devices (such as laptop chargers, full PC towers, soldering irons) which require an earth to ...
2
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0answers
13 views

Is C-SAM test needed for new baking oven for IC?

I bought a conventional oven for baking ICs. Do i need to perform C-SAM test on the units after baking? I think units will not be affected if you will use the required baking temperature and time ...
1
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2answers
65 views

Quick safety question probing 120VAC

I did read several questions about safely probing high AC voltages with an oscilloscope. I had been taught to isolate the scope, which I see now is dangerous. So I think what I should do is then ...
0
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3answers
110 views

Christmas lights - how many strands can I connect? [closed]

I am putting lights around my house this season, and am finding myself concerned about safety and what the company who makes the bulbs says is safe. I think they are being way over-cautious, because ...
4
votes
1answer
140 views

Clamping Inductive Kickback in AC Circuits

I want to eliminate/clamp the inductive kickback that would result from turning off a large inductor, such as a relay or a transformer. In a DC circuit, I would use a diode to flywheel the current. ...
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votes
1answer
62 views

How to make a 240v ac to 12v 2amp dc transformerless step down circuit [closed]

I want to make a 100-240vac to 12vdc 2amp transformerless stepdown circuit any safe reliable circuit digram is accepted
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votes
2answers
81 views

Is it safe to connect a USB port to a transistor to a power strip, so I can control Christmas lights with a USB port? [closed]

Okay, so a usb port has 4 pins, a ground, two I/O pins, and a (may or may not be switchable) 5V pin. I had an idea to to connect one of the pins to the base of a transistor. Then I would rip the ...
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2answers
83 views

Nixie Tube Voltage Safety

I have seen clock designs like this one: where the nixie tube leads are not fully inclosed. There is likely 145-170V on these lines. I am just wondering if it's safe to allow the leads to be ...
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2answers
57 views

Things to consider before baking components

I will be using my own baking oven for components/ICs. What I only know is the baking conditions of MSL devices as per Jedec or as per required baking conditions as per MSL label of the part. For ...
1
vote
1answer
68 views

Automotive or solid state relay as main switch for 3D printer?

I have 47A 12V server power supply for my 3D printer project. The idea is to add a relay before printer hardware (RAMPS, Arduino Mega clone, steppers, bed heater etc). The normally open relay is then ...
3
votes
1answer
94 views

Exceeding Relay maximum switching frequency

I read in the datasheet of the DOLD OA5611 that the maximum relay cycles/s is 10 cycles/s. Now I want to know what are the risks for the relay if I control it with a switching frequency more than 10 ...
0
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2answers
104 views

If I drive an LED whose forward voltage is 2V with a source that's 3.3V limited to 20ma, will I harm the LED?

Background: I built a 10x20 LED matrix for use inside a jack-o-lantern. The matrix is driven by 74HC595 shift registers that are connected to an Arduino. I've attached the Vcc of the shift registers ...
0
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2answers
125 views

Can touching connections between each WS2812B-LED result in a shock [duplicate]

WS2812B LED-strips are ran at 5V, and can consume up to 60mA per LED. This can quickly add up to a few amperes. Would I receive a chock if I'd touch the ...
2
votes
3answers
115 views

How can I quickly and safely make defunct electronics safe and free of charged capacitors?

I am planning a movie set which will contain old circuit boards from TVs, VCR's and other old electronics. The plan is to go to several Goodwill stores and buy up all of the TV's and such that they ...
0
votes
1answer
394 views

Why is it dangerous use a coiled extension cord

What aspect using a coiled extension cord makes it more dangerous than using an unrolled power cord. Many fire safety websites reference that an extension cord should not be used while coiled. Is ...
0
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1answer
87 views

Arduino with L298N Motor Driver and external Power

I would like to control a slave clock which requires 24v applied for approx 1/2 second in alternating directions once every minute and have bought a Arduino Uno to control the pulses. The Arduino is ...
0
votes
1answer
76 views

Clamp TO-262 transistor against heatsink?

I'm designing an enclosure for a device with mains voltage power mosfet devices. First I thought about using TO-220 MOSFETs, and mount them up against the aluminium enclosure. However, screwing them ...
1
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1answer
68 views

Using aluminium enclosure as heat sink

Can I use the aluminium enclosure of my mains powered product as a heatsink? I'm thinking about mounting TO-220 transistors pressed against the enclosure, to get away with passive cooling by using ...
0
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1answer
73 views

Extremely Simple reliable way to switch logic level signals

I am designing a failsafe system for an Unmanned Aerial Vehicle, and it needs to be able to switch 6 PWM outputs from one source to another. My initial thought was to use a series of logic level ...
1
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2answers
91 views

Is it harmful for power transformer operate without load? [closed]

I open chest of slide projector and there are power transformer from ~220V to ~6V and directly connected light bulb. If light was burned out is it harmful for power transformer operate without load? ...
1
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3answers
179 views

Is it safe to short circuit 3 x 9 V block batteries?

I'm trying to heat up a thin wire like shown in this tutorial. Since short circuiting one 9 V block battery doesn't provide enough amps to heat up the wire sufficiently. If I take 3 of those 9 V ...
2
votes
2answers
259 views

Under which possible conditions is measuring with an multimeter a danger to life ?

My knowledge of electrics is very limited, I am planning to buy a Multimeter, but I am confused when it comes to safety. I do not really know what is a danger to life when measuring a circuit with a ...
0
votes
1answer
68 views

How to calculate the power of equipments connected to a voltage regulator? [closed]

I have a voltage regulator just like this, I do not know how to use it, so, I wonder if there is a way to calculate the capacity of equipments which I connect to it so that they don't exceed its ...
0
votes
1answer
80 views

Hacking an AC power unit with a transformer

I have some mini speakers whose power pack has died. I can't find any suitable looking replacement power unit as the spec is unusual - 12V AC output 2.9A. Nothing on Amazon or eBay looks suitable. ...
0
votes
2answers
45 views

Specific Questions Regarding Use of Regulated Switching Supplies

For a project I am working on, I have 3 regulated switching supplies, 5v 5a, 12v 5a, 24v 2a. They are the standard, passively-cooled type which look like this My question: Can I stack these/have them ...
0
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2answers
154 views

Implementing Safety Shut-Off Relay In Project

I am working on a project which I have poured lots of cash into that involves water, pressure and electronics in very close proximity of each other... Lately, I have been considering adding some ...
2
votes
2answers
954 views

Why would you use a non-contact voltage detector if you have a multimeter?

I was reading this Fluke multimeter safety manual and I came across this sentence: ...
2
votes
1answer
98 views

Adding a resistive path between live conductors and earth - safety issues

(Note: I am in the UK so the terms 'line' and 'neutral' refer to the two live mains conductors) I am trying to establish a list of safety issues which I should be aware of if I decide to introduce a ...
1
vote
1answer
99 views

Intrinsically safe circuits

Is there a power threshold below which a circuit is considered to be intrinsically safe? For example, if one were to power a tiny Arduino circuit at 5vdc / 30mA = .15W could such a device be ...
3
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5answers
946 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 ...
2
votes
1answer
131 views

is it safe to have hot wire connected to ground (metal case, shield) via a capacitor?

I have opened a psu, and I saw a small capacitor is connected between one of the ac inputs and to the ground/shield. We don't have ground in our ac outlet, so a hot 110v ac line could be connected to ...
1
vote
1answer
42 views

Do I need any special equipment to make my circuit run off power from a phone/laptop charger?

Is it safe for one to replace a 5v battery source with a phone charger without installing any other components to prevent power surges or injury to any people in contact with the device? Also, is it ...
1
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2answers
387 views

DIY Laser Tag, Safety and Modulation questions

So I'm trying to build a Laser Tag game for some friends, I was wondering a couple of things Safety - I'm using 5mW red lasers from Aliexpress. I have no datasheet for the lasers, so I was wondering ...