Hi @owennugent78372
You can use a 4µF + 5µF dual capacitor but you would have to wire them in ''parallel'' connection and ***not*** ''in series'' connection to get the 9µF. If they were connected in series the total capacitance is 2.22µF
To calculate the total capacitance (Ct) when they are connected in parallel the formula is C1 + C2 + C3 etc = Ct. The formula to calculate the total capacitance when connected in series is 1/C1 + 1/C2 +1/C3 etc = 1/Ct
Here's an image showing how it is done.
Be sure to insulate all connections after soldering them etc so as to prevent accidental short circuits from occurring.
[image|3662671]
(click on image)