Capacitor Dangerous?

Other Hardware General Electronics
1

I just saw some YouTube videos of people blowing up capacitors by putting them on the wrong way. I hear that capacitors are bad for you, and the smoke could cause cancer.

I've been trying to find more information on this, because I'm just starting out with electronics and I want to know if they are dangerous or not.

I read on one website that RoHS capacitors are safe from causing cancer or other health problems. I am wondering if that's true?

Besides getting electrocuted, are there any dangers or health risks in working with Arduino projects and the components? Are you supposed to wear gloves or anything?

2

You are more likely to get cancer from the sun than a capacitor (unless it is full of PCBs as then ones that a power utility uses).
Wearing gloves is a good idea if you have a tendency to burn your self when soldering :wink:
Electronics is safe at the low voltages and currents that the arduino uses.
Welcome to a great hobby! Have fun with it.
Keep asking questions.

1 Like
3

I haven't even started soldering. I'm too scared to do it. I just use the breadboard to make things. I've been programming computers for 12 years so I decided to try out Arduino.

I have this item at home:

Honestly, I have no idea how to use it, or what it even is. I won't know what it means "rework station". I've never turned it on. Can this be used to do soldering for small projects? Is it any good?

4

Looks like a very good unit. Re-work refers to replacing and repairing things. When you are ready to do soldering go to YouTube and search for some soldering tutorials.

5

Yea that's a good idea. I'm sure once I make a few good projects, I'll want to put them together with solder.

6

I just saw some YouTube videos of people blowing up capacitors by putting them on the wrong way.

You could get burned, or some material could fly into your eye. I suppose you should wear safety glasses when you power-up a circuit for the 1st time. I've never heard of anyone being injured by an exploding capacitor, but if you've seen videos it's obvious that it could happen. Once, I did somehow manage to "flick" solder into my eye, or nearly into my eye... I had to peel it from my eyelids where they close-together. It was scary and it smarted but I didn't need medical treatment.

I hear that capacitors are bad for you, and the smoke could cause cancer.

The fumes can be pretty nasty. I had some capacitors in an amplifier blow-up a few years ago, and I had to get out of the house. They weren't backwards, but they were old and they were operating very close to their rated voltage. But, I doubt that exposure to something like that a few times in your life will cause cancer.

I read on one website that RoHS capacitors are safe from causing cancer or other health problems. I am wondering if that's true?

This is mostly related to lead. Traditional solder is made from tin & lead. And, the leads for most components were coated in solder (AKA "tinned"). Now lead has a bad reputation and, you can go RoHS or "lead free". But if the part explodes, I wouldn't count on the fumes being perfectly safe. :smiley:

Besides getting electrocuted, are there any dangers or health risks in working with Arduino projects and the components? Are you supposed to wear gloves or anything?

We are generally working with 5V or ~12V, and that's safe. I pretty-much have my fingers on low voltages all day. I believe 48V and below is considered "safe" by the regulating agencies. Anything above that and you have to make sure that connections cannot be exposed to the user/consumer. If you are working with 120 or 240V power line voltages (building you own power supplies, or switching/dimming lights, etc.) then you need to be careful.

Also, if you are working with dangerous voltages, you should also be aware that capacitors store voltage (sometimes for several minutes or more, depending the circuit). It's an old "trick" to charge-up a capacitor to 100V or so, and toss it to someone (without touching the leads yourself).

P.S.
There was a post (maybe yesterday) about trying to make soldering safer - I mentioned that soldering is less dangerous than sports. I've been working in electronics for many years... I've been shocked and I've been burned on soldering irons, but I've never personally seen anyone hurt badly enough to go to the emergency room. The worst shock I've had was from a spark plug on a lawn mower, and the worst burn I've had is from a car radiator.

7

Agreed welcome to an amazing hobby!

Chances are now matter how careful you are if you use soldering irons for any length of time you will eventually accidentally burn yourself, I have done it in the past and I'm not gonna lie its extremely unpleasant. But it certainly wont kill you, and you can get burned equally as bad from touching a scalding pot or stove etc. so its not necessarily any more dangerous than stuff you cook with.

But definitely watch some YouTube videos and get a good idea of how to solder first; its not hard but does take time to master. Likely your first time you'll be frustrated with the results (I know I was) but you can pick up the knack really quickly. And of course it is an amazing tool and allows you to make your projects more permanent because you can transfer them off of breadboard onto perf board.

Some people wear safety glasses while soldering too just in case some were to flick towards their face and while it is likely a very good idea I personally have never done it.

Oh and again if you do electronics for any length of time eventually you will wire something backwards of plug something in incorrectly. It comes with the territory. To be sure if you are careful and measure things first and use caution you can prevent a lot of accidents, but as LarryD said at the voltages and currents on an Arduino a mistake certainly wont be as dangerous as if you were working with mains electricity. About a year ago I plugged a 5V video camera into a 12V battery (thought I had the wire to a 5V source),,, and poof. I got the magic smoke and I was down a video camera. So the moral is mistakes are part of learning but start off small so if you make a mistake then it wont cost you as much.

8

Sparkfun has a pretty good beginner soldering tutorial
https://learn.sparkfun.com/tutorials/how-to-solder---through-hole-soldering
You are starting with a lot better unit than most beginners do so it will be much easier to get quality joints.

9

Thanks for all the responses. I'm not going to attempt soldering yet, but I am going to start getting a few more parts and trying to make some "real" projects first. Something besides what's in the starter kit.

I'm trying to get a bunch of extra resistors, capacitors, and other things so that I have them on hand. I'm finding it hard to find the right things. From the starter kit, it looks like 220 and 10K resistors are most commonly used in those projects, so I think I just need to get those two to get started.

I'm still really confused as to how they figure out what to use. Sometimes for LEDs they use a 220 resistor, but then when they have a wiring coming out of the Arduino pins they use a 10K resistor. They also use different size capacitors.

Right now, I have no idea how to pick the right parts for a project. I just use what the book tells me to use.

I'm just really worried about destroying something.

10

The exact value depends on what your are trying to do. Filter caps used after a bridge rectifier are usually in the order of 4700uF (really big) and yet capacitors used in conjunction with crystals are often 0.1uF - quite small compared to 4700.

Resistors are used a lot more than capacitors when you are starting out; at least that was so in my case. Pull up/pull down resistors are usually larger (10K). Resistors used to limit current for either LEDs or the base of transistors are usually down closer to the 200 ohm range.

The two first formulas I ever learned were:
V = I/R (voltage = current divided by resistance)
and
P=IV 9 (power = current times voltage)
The units are always in Volts (V), Amps (I), and Ohms (R), and watts (P).

Hopefully you can use those two formulas in conjunction with instructions in the book to have some more fun and understand what is going on a little more.

11

The book shows those calculations but at first its hard to wrap my head around them, since I can't actually see the electricity. I'm more of a visual learner.

I get stuck on the topics. I want to get a power adapter so I don't have to keep using 9V batteries. I found some 9V DC adapters, but I have to chose if I want 1, 3 or 5 amps.

I've been trying all night to make sense of what that means so I get the right one. I read the pages on this website and it says that anything over 40 mA is too much. But that's only 0.02 amps. So it seems like 1 amp is too much.

Hopefully, things click soon, so I get this.

12

That power adapter will work fine.

The arduino will only take as much current as it needs. I believe its about 35mA. So the 1A simply means that is how much current you can draw from the power adapter. If you tried to draw more than 1A the voltage would start to fall below 5V.

The 40mA rating is much current you can safely draw from one pin. This is a hardware limitation and is determined by the atmega328p (the microcontroller on the arduino).

13

Well thanks for the help.

I'll work on this more in the morning, maybe I can get learn something.

14

capacitors used in conjunction with crystals are often 0.1uF

No.
Capacitors used with crystals are six orders of magnitude smaller than this, typically 22pF. A pF is ten to the minus 12 where as a uF is ten to the minus six.

15

Can capacitors be dangerous?

Electrolytic capacitors in electronic equipment that has not been switched on for a long time can sometimes fail catastrophically.

Capacitors that are 'polarised' (have connections marked + and -) must clearly always be connected the correct way round, so it is important to be meticulous when constructing a circuit. Polarised capacitors include electrolytic and tantalum capacitors.

Capacitors should always be used within their stated voltage rating, and whenever possible with a safety margin to allow for any momentary voltage spikes that might occur that could puncture the dielectric.

It is generally good practice when designing and building electronic circuits to rate components conservatively (to 'derate' them) to allow a good margin for possible variations in component tolerances, voltage and temperature etc.

16

A statistician would argue that working with electronics must be dangerous because it can be proven that everyone who does so will eventually die.

Stop worrying, build a few examples, have fun.

Yes you may (that should be "will") destroy things along the way but that's just part of the learning process. If we didn't fail once in a while we wouldn't learn much.

Is it dangerous - no it's not - unless you are foolishly working with high voltages without knowing what you are doing.

17

Sure electronics is a pretty safe hobby as long as you avoid working with high voltages...

But some capacitors do when misused have a small potential for unwanted consequences:

Unlikely, yes, but you wouldn't want any risk of carelessly starting a fire or asphyxiating your pet parrot while you're out?

18

jackrae:
Yes you may (that should be "will") destroy things along the way but that's just part of the learning process. If we didn't fail once in a while we wouldn't learn much.

Adafruit makes a merit badge for that: Sparky the Magic Blue Smoke Monster - Skill badge, iron-on patch : ID 565 : Adafruit Industries, Unique & fun DIY electronics and kits

19

Thanks for the replies everyone.

Those badges are funny, I think I'm going to get a few, and thanks for the website, looks like I have another resource to get parts from.

20

If you want a bunch of basic components like LEDs, diodes, resistors, transistors, or capacitors, don't buy from Sparkfun or Adafruit, they mark up the price really high. It's fine if you're buying something else and want to chip in some basic components along for the ride, but if you want to really stock up, Digikey or Mouser is much better.

For comparison:

They aren't exactly equivalent (Mouser one is 1/4 W, SF is 1/6 W) but the price difference is massive. 100 resistors from Sparkfun would cost $40, but you can get 1,000 for $9 from Mouser.

Granted, Digikey and Mouser are much more difficult to use since they have literally millions of different products (such as 4,282 different kinds of carbon film, through-hole resistors, versus the 3 that Sparkfun has), but the price difference can be worth it. And you can always ask someone if you're having trouble finding something.