DIY Lego Light Sensor

as the light sensors that came with my first and second rcx where not useable when you want a laser guided robot, i diceded to make my own light sensors
and here it is my first instructable :)
excuse me for my bad english i'm not good at spelling and i'm dutch so... please if there is something incorrectly spelled let me know then i can fix it or pay more attention to it

Step 1: Get the Stuff

ok first of all i used a way to light LDR (light dependent risitor) it did not have enough resitance so my light sensor is a bit sensitive..

but what you will need is a LDR that has about 3500 ohm's when you expose it to a simple laser pen
mine didn't have that much resitance so i fitted a aditional risistor of 1500 ohms.
but that is all up to you

ok what you need:
an LDR
A conductive lego strip
A lego brik
maybe an aditional risistor

Step 2: Constructing

first of all you need to get the conductive plate to the right size, i used 2x1 but you can use any size you want.
next you need to get the condutest on the top exposed just cut them away with a knife or something. only 2 are needed so leave the rest the way the were if there is a rest.
first if you use an aditional resistor get some solder on the conductor. cut the resitor to the correct size and place it.
next you need te get the LDR on cut the wire's to the correct size and solder them to the conductive plate, if you have a resistor you need te get one wire to the other end of the resistor.

Step 3: Assemblage

now you need to put it all together.
sometime's you may need to get things out of the lego brick to get it fitting, try some with it
and when you're doen trying you can gleu it together just around the edges of the bricj abd then press the part you just made tightly on. then you can gleu the sensor to the brick and you're done

Step 4: Tips and Hints

i reccomend to first test you're light sensor before putting it together
and you can use some wire instead of directly mounting it on the conductive plate