Auto Dim Xenarc/Liliput with illumination wire from radio harness?

**visenri** · 01-06-2007, 12:02 PM

The wire you should cut is the control wire in the inverter conector, in the pictures labeled as CONTROL (it may be different in your model).

You can check it with a multimeter, the control wire changes from 0 to 3.3V when you adjust backlight from 100 to 0.

Any type of small relay will do the work.

Just be sure to connect as follows:
Cut the CONTROL wire.
Connect the wire that goes to the inverter to the COMMON of the relay.
Connect NO contact to the wire comming from the screen mainboard.
Connect NC contact to gnd.

When you close relay, inverter gets 3.3V (depends on backlight setting)
When you open relay, inverter gets 0V, full backlight.

**kelmk** · 03-16-2008, 12:24 AM

I have a CTF700-SH from cartft. It has a light sensor that is used for auto dimmer. How would I hook up this sensor to my dimmer wire from my radio harness?

**kuo** · 03-18-2008, 02:38 PM

just wondering... if it has a light sensor already built in, why do you want to hook it up to your car's dimmer? does it not work to your liking?

**kelmk** · 03-18-2008, 02:46 PM

It doesn't dim as low as I would like. I run 100 brightness during the day and at night I would like 50 but the auto dim only seems to drop it maybe to 70 or 80.

**visenri** · 03-26-2008, 05:45 PM

Originally Posted by kelmk

It doesn't dim as low as I would like. I run 100 brightness during the day and at night I would like 50 but the auto dim only seems to drop it maybe to 70 or 80.

In your case i would take one of these two solutions:

1- Build my new dimmer (with microcontroller)

check: http://www.solocarputer.com/phpbb2/v...201&highlight=

It has two working modes, in simple mode, if the dimmer input is activated (night mode) it dimms the screen brightness to what you have set in the backlight setting (limited to 1% to avoid CCFL powering off), if dimmer input is not activated, backlight is set to 100% (0 Volts day mode). All brightness changes are done smoothly. It has also a serial mode (advanced mode), to set the brightness from a serial transmitter at 15ms per bit (in this mode backlight screen setting has no effect).

2-Build a simple transistor or relay switch, to change between full backlight (0 Volts , day mode) or backlight set to screen setting (night mode). In my last post i have explained how to do it with a relay, if you want transistors, tell me.

**a2carat** · 09-24-2008, 05:30 PM

anybody done this on a liliput? is it the same as in the xenarc?

i have no experience with this kind of stuff so i'll see if I can figure it out. I guess if its not the same it should be similar... so I'll start from there

thanks

**skuller** · 09-25-2008, 01:01 AM

the new led liliput or the ccfl one?
you can't use this modification to control the led one.
If it's ccfl, it should work just fine.

**a2carat** · 09-25-2008, 01:36 PM

its a ccfl but I only have 2 wires running to the backlight assuming +/- not four like the xenarc can i just put a pot and control it that way?

**WRed** · 11-15-2008, 10:29 PM

Bump for an answer. Looking to do this on my ccfl lilliput.

**visenri** · 11-30-2008, 05:54 PM

Two wires means your inverter doesn't have a control wire, so, you can't do this simple mod.

But you can lower the voltage that goes to the 12V wire.

To do this you can put some diodes in series like 1n4001 to lower 0.6V per diode. To switch between dimmed and full brightness, a relay can do the work, it's NC contact must be in parallel with the diodes, and it's coil must be connected to car light circuit. When you turn on the lights, NC contact opens and you get a voltage drop across the diodes.

You can do a more sophisticated dimmer with an ajustable regulator instead of diodes.