I was thinking of adding something like this into the dash of my electric car since I have tons of useless guages to remove now. But it doesn't appear to have a backlight. Being that it is a proprietary LCD screen.. how hard would it be to add backlighting?
Post by iamdenteddisk on May 5, 2008 16:48:23 GMT -5
adding a simple backlight to an existing lcd device isnt that hard just a few things to be said ,useing a single color of choice LED/'s sieze of screen you probably will want atleast four of them arange in paralell and a piece of mirror behind the screen ,draw voltage through a 470ohm resistor atleast this will slow the current draw of the circuit and also lenghten the life of the led's this value is estimated and be aware that the resistor should be a 1/2 to 1 watt in rateing incase to handle a load of possible hi peek as a automotive system normaly can be 9-19Vdc not the 12v you would expect this is a variance and is normal most led manufactures will list on package or tell you on the phone of required lighting current for the led you buy ,and if soldered in paralell you can simply add the led's current requirements to get its total requirements ,I suggest building the circuit out of the device by pokeing the legs of each device through a card sized piece of cardboard then useing a 30guage "piece of phone wire" wrap the wire to the legs on the underside of the board pop the car hood and "lay the circuit board on a rubber floormat and touch the power leads to the batt "remember the long leg of the led is pos+" dose it light? did the resistor get hot? if the answers to these two questions are yes then no,try starting the car and repeat is the answers still yes then no? ifso then good. your ready to install ,if the resistor gets hot on test 1 or 2 then get a higher ohm rateing and if it dont light at all you probably polerized it wrong "hooked it up backwards" led's use verry little current but single color led's dont like reverse current they are diodes"one way gates" you might even try multi color led's as they light in both directions but you still will want to orient them the same so you get a uniform color from all. this prety much should do it for automotive backlight as long as the heat dissapation isnt a problem and current is low enough you might poke around a bit to find an inboard Vsource for the light use a volmeter also I have used a capacitor and an intensional push switch to have intermitent light you push the button charge the cap it slowly drains till lights out. good luck! and do use the cardboard testboard its my best trick for prototypeing a circuit "worst senario you get a wire crossed it burns the cardboard not a LCD display right, goodluck firstname.lastname@example.org