Electronics 2000

Hi Guys just beginning to decorate the bathroom, a real pain in the arse
Have installed 3 ceiling lights use to be 50w spot each, changed these to 3w LED each, you know the flush to the ceiling type.
Swear there a bit brighter as well, but it simply could be that it's the new paint.
My question is
Would it be possible for the LED's to fade On/Off perhaps about 5 or so seconds to switch on & off ?
and if so how

Thanx You
Regards
Gary

It can be done... some LEDs dont like dimers... off the top of my head run the LEDs through a transistor and control time with capacitor and a resistor... hmm need to think about it.

Tar&stuff.

Hi Piratepaul, thanx for the interest, reading that I might have to get inside light bulb, add capacitor and resistor, for me thats a no go.
looks like as far as I have been reading, it's not possible, using LED that can be dimmed suggest a possibility it can be done, but even then it's a bit over the top.
Again cheers for the input.

Regards
Gary

piratepaul wrote:It can be done... some LEDs dont like dimers... off the top of my head run the LEDs through a transistor and control time with capacitor and a resistor... hmm need to think about it.

Tar&stuff.

Hi Piratepaul, never one to really give up, came across this schematic for a light dimmer circuit, I think it might be what I'm looking for ?
what do you think, I will need some dimmable led's
Found this at http://www.electroschematics.com/10139/ ... ive-reset/
would appreciate if you could give this a once over
Regards
Gary

I don't think that will work as the circuit is a pulse width modulation. An led will probably flicker

ahhh shiiiit, is it possible if this does happen, to increase modulation till my eyes don't see the flicker ?
however I would have to read more to find out the how-to,
Thanx Pauldf for your input, any thoughts on how I could increase the modulation .

To dim LEDs you somehow need to limit the current flowing through them, reducing the voltage may work but not with clipping a sine wave. The latter works with a normal filament lamp as it creates light by the heating of a filament, the remaining heat in the filament keeps it glowing hence it doesn't matter about when the supply is in the off part of the cycle. With an LED you don't have this bonus hence it will extinguish for that part of the cycle.

I can be done. another .

The PWM thingi will prob switch on and off a MHz or KHz so will not be visible but I would advise welding goggles when in the shower, LED's can damage the eyes.
Time can be controled with a variable resistor and a cap, feed this into an opamp (I would need to do my opamp homework for the configuration, perhaps someone who knows opamps could help) feed the output to a transistor and run the LED's from the transistor.

A thermistor is another possibility hmmm (needs thought)

Tar&stuff.

You also need a bridge rectifier... the component costs are pennies.
Tar&stuff.