LCD to LED conversions?

[OldLes]

Mark, I have thought of that, but not come up with an answer yet. There is probably a simple way to control the voltage (resistor?) and leave where it seems OK. There are dedicated controllers which could equally be "merged" into the existing control with a bit of ingenuity, but a bit beyond me.
First thing is to find time to complete the mod, but busy watching the TT last week, hence am currently under control from SWMBO, plus I have a motor cycle to finish off for the road.
It is a couple of week's since I last looked at it, only to discover it was similar to a laptop, just having a pair of very thin CCFLs on each side of a perspex (or whatever) diffusion screen.
I am hoping to route some slots into the perspex for the LEDs which should get around the space limitations of the existing arrangement.
Les

[Keith]

Hi,

LEDs use a pulsed supply, so PWM is used to control the brightness, simples!

Keith

[OldLes]

Hi Keith, Yes, I had read up a bit on LED controls, but for my little experiment, the LEDs I am using are a string (or strings) of LEDs designed for running from a 12V supply. The Toshiba I am trying it on has a 12V supply supply which I will use for the LEDs. If I think they are too bright, a series resistor should do the trick.
Les.

[Keith]

Hi Les

Using a pulsed supply is best as the LEDs will use less power. I am sure something will be available from China on Ebay.
 Is the 12V supply in the Tosh powerful enough for the LEDs? If the supply is used for other things it may already be near it's limit.

Keith

[Davy]

How about ramping a  'reggy' say a LM317 with a 555

Dave

[OldLes]

Kieth, I think the LEDs will draw considerably less current than the CCFLs. I think it was only a couple of amps or less to light the full roll of LEDs (300 or 500, I forget offhand).
Davy, I still need to find time to embed the LEDs in the diffusion screen before I progress further, but maybe I will come back and ask you to knock up a circuit for me to try!
Les.

[Keith]

Hi Les

If you do an internet search for "pwm circuit for led dimmer" you should find lots easy circuits for a dimmer.

Just looked on ebay and you can get ready made for a couple of quid!

Keith

[Davy]

Well, I've got Labcenter PCB Cad loaded up here, a PCB is no trouble.... just Sir Kit is required, I really should  errizit circuit?

Duno why, put I save the diffusers out of duff displays, some good thick plastic in some of em.

Davy