# MAKE: EX 6 Components

Discussion in 'General Electronics Discussion' started by nyancatvsghosthead, Sep 18, 2012.

117
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Jan 7, 2012
I was reading the components needed for experiment six of MAKE: Electronics and realized that it doesn't say how many volts the capacitor needs. It just says that it needs 1000 microfarads. I don't see how many volts it needs. Also, how can a capacitor have volts? I guess the potential difference between both terminals of the capacitor right? Just wondering.

Anyways, it just doesn't happen to be so that they explicitly state how many volts I need in the capacitor. As always, responses appreciated.

2. ### davennModerator

13,991
2,018
Sep 5, 2009
what voltage is the project(s) being supplied with ?

5V ? 12 V ?

as a rule of thumb use a cap that has a rating of twice the voltage being used
so for example a 12V PSU then use a 25V cap
it doesnt matter if the voltage rating of the cap is substantially higher say 35V or 50V caps on a 12V supply

Dave

3. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,505
2,852
Jan 21, 2010
the voltage rating of a capacitor is the highest voltage that can safely be placed across it.

If you're working with (say) a 9 volt battery then a 16V rated capacitor would be fine, as would any voltage rating higher than that.

As the voltage rating goes up, the capacitors generally become larger, and often more expensive.

Common voltage ratings are 6.3V 10V 16V, 25V 35V 50V 63V, 100V, although not all are available for all capacitors, and some capacitors are manufactured with other voltage ratings.

117
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Jan 7, 2012
Wait, I feel stupid. I forgot something I read. It said at least 25 volts. I know that's not exact but should I just find a 25 volt capacitor? It would be stupid of me not to right?

5. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,505
2,852
Jan 21, 2010
If you've already bought some capacitors and their voltage rating is 25V or higher, then you are OK.

if they are a lower voltage, but still significantly greater than the voltages you're going to use, then it's still OK.

If the voltage is only a couple of volts higher than your battery voltage, then you'll be OK for temporary circuits you build up on a breadboard.

If they are less than your battery voltage you probably should get some with higher voltage ratings.

Don't panic. For temporary use, especially with low voltages and low stress (e.g. no elevated temperature) even a slight overvoltage (10% TO 20%) is unlikely to cause any dramatic failure in the short term (but I wouldn't recommend it)