Incorrect Capacitor for voltage regulator ?

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1

Hi all

I am wanting to use a L7808CV voltage regulator to drop my supply ( varies between 12 to 14v ) to 8 volts, to power a Mega 2560 board on the Vin pin. My thinking is that if I can supply a constant 8V to the Mega, its onboard regulator has less stress placed on it.

From research, I understand that I need 2 capacitors -- 0.33uF and 0.1uF

I have these components :

Radial Z5U ceramic cap,100nF 50V 5mm
part no : 5381449 from http://za.rs-online.com

KS radial Al electrolytic cap,0.33uF 50V
part no : 116975

I understand that the polarity of the capacitors is important. On the 0.33uF cap I can see the negative side printed, but on the 100nF ( is this the same as 0.1uF? ) I do not see any polarity markings.

Do I have the wrong capacitors ? If so, could you point me to the correct part numbers ?

Also, can I use the L7808 without the capacitors ? I recall that the Mega board has its own voltage regulator as it can accept up to 20V but runs on 5V.

2

No the parts are right. The 0.1uF is not polerised so it dosn't matter what way round it is.

3

Thanks a million Mike.

I really appreciate the fast reply. Am wanting to start assembly in the morning.

4

@DaveO

When I built my circuit with a voltage regulator, I use there values :

Input of the regulator : 10uF to 100uF and 100nF Voltage : above 35 V.

Output : 10uF to 47uF and 100nF Voltage : above 35 V <-- in case the regulator decide to go "south"

My "standard"...