Hello, i would like to create a simple circuit to charge a 100uF/50v capacitor. I tried but it didnt work, if you can help me let me know
Put the capacitor between the positive and negative rail.
So sorry to hear that your simple circuit didn't work. If only I could help... try this circuit instead...
But remember - train time is anytime.
So i can just direcly connect 5v on positive and ground on negative?
Yes, but then you can't discharge it without disconnecting it.
So please post a diagram of your "simple circuit" and explain what you want to do with it.
I'll betcha' it DID WORK! 
It MIGHT have discharged faster than you expected.
Do you have a multimeter? Charge-up the connector and then connect the meter and NOTHING ELSE. Most meters have an input resistance of 1M or more so that would give you an RC Time Constant of 100 seconds or more and you should see it slowly discharging.
Or, you can charge it to 5V and then connect it between the Arduino's analog input and ground and run the Analog Read Serial Example. But, you should put a resistor of 1M or more in parallel because otherwise the analog input will "float up" and you'll read some unknown voltage. (If the capacitor is discharged when you 1st connect it, it will read zero but it MIGHT very-slowly float-up and charge the capacitor.)
Seems that some of out brightest members are acting a bit immature in their responses.
This link is to a "foundational" area of the website. It will help with terminology and some background info:
Capacitance Meter and RC Time Constants | Arduino
This will take you a little further:
When it comes to charging or discharging a capacitor: imagine: without any resistor in the line - the current taken or drawn is "infinite"!
You need a series resistor, for charging and discharging. Without any resistor, just put the C on plus and minus - it draws such a huge current !!!!!
Also if you discharge: with a single wire between plus and minus on C - such a huge current!!!! (and you can see sparks, solder iron or even the C will explode)!
Don't use any C without any resistor !!!! It is very risky.
Also be aware what type of C you use: if you use an electrolyte capacitor - it is polarized!
If you flip plus and minus - the C will explode!! And you have all the poisoning stuff in year eyes!!!!!
A Cap is like a battery: provide a higher, "positive" voltage and it will charge (via a resistor!!!!).
Disconnect the power, now drain the cap: a resistor from plus to ground (common).
The current flows in opposite directions: when charging into cap, when discharging out from it.
Imagine it really as a battery, you would charge or discharge. But never do charge or discharge without any "current limiting" resistor: the current a cap (or battery) can provide is "infinite": it would heat up the cap, the wire, so much that you would create a fire!
Only in theory with ideal components. The reality is different and "infinite" is not a very good term.
What is true is that exceeding the manufacturer datasheet ratings could lead to the damage of the microcontroller: in this case, the CMOS output gate current.
Well, I've seen it take a huge bite out of a screwdriver blade. 
Sure, real world does not have "infinity". What I meant: "any dramatically high current" which is just limited by the internal resistance of the cap itself at the end. If you have a good cap, with low resistance, e.g. these "low ESR" types - the current is "unlimited" (and can be any current in Amps).
"infinite" is not there - true. But for me it means "any unlimited and unknown number".
And this is true for the current into or from a capacitor - without any external resistor used.
Yes but....
Yes you can connect your capacitor to the 5V rail. However if the capacitor has no charge on it (aka 0 volts) when you connect it to the 5v rail it will act as a shorted circuit for a short time ( small fraction of a second).
You should know that its fine for a few times but if you are going to do this over and over (100+ times) you should look into you 5V supply to be sure the capacitor initial load will not damage it in the long run.
Arduino 5V regulators will be fine in the long run, however it is possible that connection of your capacitor (with 0 volts on it) may reset your processor.
CAUTION 100µF capacitors have a polarity. Be sure + it to the 5V rail and - to ground.
Oh and I don't think the other replies are immature its just that we continually get posts with questions without enough detail to know what the OP (you in this case) is asking. So I would say it's more from frustration than immaturity (although I agree sometimes they are the same)
All fine and correct for my understanding.
Just to bear in mind:
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a large capacitor might draw for a longer period of time a high current (which can even damage a power supply, LDO, SMPS ... at least to let them shut down due to high current
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Yes, such caps with high capacity are most likely "electrolyte caps" which are polarized
Personally, I would never try any cycle, not even ONE when cap is so large, on a simple logic gate. They cannot deal with such a high current peak. 100 microF on a TTL logic gate: it sounds to me like "killing immediately" (on the very first trial). If so, I would expect to see a current limiting resistor (e.g. 10K, 100K), but not 1K: 1K with 100 microF sounds to me as: "it creates such a high current in a peak - almost all small ICs will be dead".
There is no need to be afraid of damaging outputs with a 1 k resistor and capacitor in series.
Even if the resistor is directly connected to ground the current will be only 5 mA.
No problem at all.
Isn't 100 uF a fairly regular value for a power supply output?
In the old days (before switching power supplies 1000 uF was standard.
The inrush will be only very short. Usually it is heat that destroys things, not currents.
Many power supplies are shortcut protected.
It's kind of amusing how many hundreds of electrolytic capacitors I have wired wrong, yet I have never had one explode... Still, I wouldn't recommend it.
Well, not quite. It is limited by the source it is "plugged in" to.
Begginer has never explained, is this some sub circuit in a system, or just a bench experiment? As a sub circuit, charging a 100uF cap from Vcc arbitrarily could cause problems due to the instantaneous drop to zero volts resulting from the regulator current limiting. Such as, a reset of the MCU.
How do you know that?
We're on post 20, and all we have from Begginer is two vague sentences, and one question. Why even play?