Capacitor question

[thejuggla1]

I know they store energy and release it similar to a battery, but my question is about voltage.

I read that the voltage of a capacitor is determined by the voltage put into it, I dunno if that is true or not, just the first site that came up on google. Now my question is why do Caps have voltage numbers on them? Is that the 'max' voltage they can take? Like a 4V cap could take 2 1.5 V batteries seriesed but not 3 of the in a series?

And I am looking to add a cap to a circuit that runs off 9 V, I would have to get a cap that accepts atleast 9V or higher?

 

[dougy83]

Yep you're right. the voltage written on the side of a cap is the maximum it can handle

 

[Sceadwian]

Keep in mind those voltage values are only over a limited temperature range, if you expect high temperatures to be involved the effective voltage they can be run at is much lower. Double or tripple your working voltage is not uncommon.

 

[thejuggla1]

Keep in mind those voltage values are only over a limited temperature range, if you expect high temperatures to be involved the effective voltage they can be run at is much lower. Double or tripple your working voltage is not uncommon.

I am looking at this diagram

https://www.qsl.net/yo5ofh/hobby circuits/circuit pictures/traffic.gif


It runs off 9V I dunno if it becomes really hot or not, would you recommend going with a higher Volt Capacitor?

I am looking to also modify it adding 2 more 'sets' of traffic lights since this diagram only has 1 for N/S and W/E not 1 for each directions. Would you recommend uping the cap to about 20 uF?

 

[Sceadwian]

If it's run from a nine volt battery everything should be fine as a 9 volt battery doesn't stay 9 volts for long, it's voltage drops very fast.

 

[thejuggla1]

Actually once I finish this, I was planning on making a 120V to 9V step down transformer, assuming it is not to hard(I plan on running other things off it also)

But ill collect the info on that when time comes.