I'm very new to the Arduino Uno and I'm on project 5 of the booklet that came with it. This introduces 100uf capacitors. I was doing well until I read to be careful because it can explode if placed wrong, which stopped me in my tracks because I'm doing this with my young nephew. I guess my questions are, if a 100uf explodes is it a small poof of something dangerous? I bought a multimeter but to help me feel more confident but I'm new to using that as well. Also, do I need to discharge it once I'm done with the project? If so how do I do that safely? My last question is ca I store these components in a regular plastic organizer/box or do they have to be in a anti static container of some sort? Any newbie advice would be appreciated, thanks!
Electrolytic caps have their leads marked (+) and (-)
Sometimes only one leg is marked… the other is obviously the other.
The + positive leg goes to the ‘more positive’ of the connected points.
e.g. +5V and ground (0V)
- or in odd cases… 0V and (-12V (would be the more negative)
Always use the right cap in the selected location. The biggest factor is an operating voltage higher than the highest likely voltage at the connected points
e.g 10V 100uF would be fine on a 5V circuit.
It’s a valid question, because depending in the ratings of the cap, the ‘explosion’ can be significant - taking out an eye, or burning you with hot guts/electrolyte.
A 100uF cap connected to 5V and in reverse will pop. Not real dangerous but could be an eye hazard. Keep your face away from the circuit when powering it up. Just be very careful to observe polarity. The cap should have its polarity clearly marked.
Not a 100uF charged to 5V. In old TV sets there were caps charged to thousands of volts. Those were very dangerous.
Resistors, caps, LEDs and such do not need to be stored in static free containers. ICs and MOSFETs may benefit by being stored in anti-static.
Well... It's not going to explode if you are powering everything from USB because there is not enough energy/current available. With USB power it might just overheat and short-out, or it might even survive.
But it might be dangerous with a 10 Amp power supply.
I've seen it happen a couple of times. Most of the time I've just seen the end-result of a black-burned, and possibly shorted, capacitor. But a few times, I've seen them "pop".
So it's not likely to happen with low voltage & current, but with kids... I dunno... You don't want to take any chances....
When I was taking high school electronics some of us "more advanced" students were in a separate lab with no teacher and sometimes we'd connect an electrolytic capacitor to the 120V power line. It would explode like a firecracker!
There is aluminum inside and of course it could cause a small burn or a serious eye injury. Nobody in my high-school class got hurt, and we probably looked-away to protect our eyes, but I don't really remember... Oh... I was wearing glasses...
Leaving a low-voltage (1) charge won't hurt anything and it will self-discharge in a few seconds (or maybe several seconds depending on the internal leakage resistance)
If it makes you feel better you can discharge it through a 1K resistor (the value isn't actually critical). (RC Time Constant)
Storage of passive components (capacitors, resistors, and inductors) is not critical.
Semiconductors can be damaged by static discharge so they should be handled and stored "carefully".
Some are more static-sensitive than others, and once mounted on a circuit board the other components provide some protection. But I had an Arduino die for unknown reasons and that might have been caused by static.
(1) More than 50V is considered dangerous by most regulatory agencies and if you pick-up a capacitor charged to 50V and touch the leads you might feel a small shock. At 100V you are likely to feel an "uncomfortable" shock, but under "most conditions" it won't hurt-injure you.
You will be OK. The number 1 thing to keep in mind is always wear protective eye covering. They only have to work once to save an eye.
If you want to see how big the bang is when a capacitor explodes take one outside, use 3 or 4m of cable to the capacitor so you can stand well back, connect a power supply with reverse polarity and watch what happens. Probably best to wear eye protection.
Usually the outside is minus.
The middle lead is usually plus.
They do explode and yes I was happy not to be near (especially with my eyes).
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