I've got a low voltage PWM unit which is controlled by a DC voltage. Can
be used for motor or light control etc.

In this case I want to use it to drive high power LEDs. Which it does just
fine.

What I want to do is have it ramp up to max when a switch is made, and
ramp down to minimum when it's opened. I've experimented with RC circuits
which do sort of work - but don't give a linear fade in and fade out.
Any clever ideas? Preferably using just one cheap IC that I'll have in my
box...;-)

It would also be nice to arrange things so it takes no current when the
switch is off. Although I can get round this.

--
*Why are a wise man and a wise guy opposites?

Dave Plowman London SW
To e-mail, change noise into sound.