50w Led soft-start

[Magician]

Hi Guys, I have a 50w LED cool white above my planted aquarium fish tank, driver is DC constant currant 24v to 36v, hooked up to a digital timer, comes on at midday and off at 8pm.

What I would like, is a soft start and finish... Start. taking about 20mins to an hour to ramp up to 100% (full brightness), and again 20 mins or so to an hour to ramp down to 0% (light off), the times are subjective
Have scoured the web for some sort of schematic
Can I simply use an RC circuit ? however I have know Idea the size of resistor and capacitor
Stuck


Advice would be much appreciated, starting to obsess over this

Regards
Gary

[Richard]

Search for "soft start schematics" and "long period timers"

[piratepaul]

Hhhhhhhm. A DA converter and a counter that counts for 20 mins off the top of my head... Or perhaps 5 DA converters with outputs in series to give 25V output.

[piratepaul]

I have bolloxed this up, the DA converters will go bang... Resistors in series with the lamp which are switched on and off with transistors ie the transistors bypass the resitors one at a time dimming in steps.... There must be a better way, I will av a fink.

[Magician]

Hi guys thanx for your input, I bought (China) an Programmable LED Timer Controller, thinking this might be Ideal, unfortunately, it's 12 to 24volt DC, even then I don't think I could use the constant currant driver, worth the £20 though, just to keep up the drive to find a simple daft soft on and off, it cant be that hard, can it !
Will beat this I hope.