Grassy said:

Thanks!, thats explained a lot, leaves/creates a few questions

Excellent! If I somehow explained everything in one paragraph, there

would be no reason to go on living. ;-)

so how do you calculate capacitor size, is it possible to put too

large a capacitor as the decoupler.

The formula that relates current to the rate of change of capacitor

voltage is a lot like the one that relates inductor voltage to the

rate of change of current through it. I=C*(dv/dt)

I is in amperes, C in farads, and dv/dt in volts per second. This

tells you that you can pass an ampere through a 1 farad capacitor and

the voltage will change 1 volt per second. The trick is to apply this

to short and variable spikes of current and calculate how the voltage

will change. Lots of people skip the calculus and find out the needed

capacitance by experiment (look at the supply voltage with a scope and

keep increasing the capacitance till the bounce gets small enough).

What size of capacitor do you need before you can feel a discharge?.

That is more dependent on the voltage stored across the capacitor,

than the size. As long as the voltage is less than about 50 volts,

dry skin will limit the current to less than a painful amount. Tough

your tongue across one, and the voltage has to be a lot lower to make

the experience not "shocking". The size of the capacitor just varies

how long the shock will go on, before the voltage has run down too low

to feel.

Building a Hulda Clarke "zapper" and that says .0047uF for decouple, If

you use a larger one, is that entire charge delivered for each pulse

Decoupling caps do not normally discharge during circuit operation.

They just sit there across the supply lines, holding a nearly constant

voltage. I would have to see a schematic to be sure what they are

describing is really a decoupling cap, and not some other circuit

function.

I guess I need to read more about capacitor charge times and discharge

rates.

They are very versatile components with lots of applications.