Dear All,

Sorry if this is a basic question. I deed search the web for an answer, but could find one.

I'm designing a power supply with various outputs (+24, +15, +10, -15,

-5), using LM78/79XX line regulators. The datasheet states that a .1 uF capacitor should be placed at the output to improve transient response, and a .22 uF at the input, if the regulator is far from the filter capacitor. But when I look at designs published in journal and such, I found all kind of variations, including different values for the input cap., even if the regulator is close to the filter capacitor (in a PCB), and usually an additional electrolytic capacitor at output.

So I guess my question are: 1 - do I need a capacitor at input and what is is value? (and is purpose).

2 - Do I need an additional electrolytic capacitor at output, besides the 0.1uF, and how do I calculate is value.If anyone knows of a bibliographic reference ware this things are explained, I would appreciate.

Regards

Jos=E9 Mariano