Hi everyone:

I and buddhika has a project for the auo dimmer light and warning system.

we found the a small circuit on the website, it's auto dimmer light circuit, our project is different to that, but we would like to know the theroy and then make our one.

That circuit showing at the first week:

But we did not know the circuit is working or not, so we just is trying to make one for the test.

The componet for the circuit:

R1 = 1K,
P1 = 10 K,
LDR = ( We bought the LDR in the Jaycar )
T1 = BC547,
D1 = 1N4007
Relay = coil 400 Ohms, DPDT, 12 volts

LDR in that circuit is 10-50K

we can not find the exactly same one:

Light Dependent Resistor (LDR) - 8.5 x 10.1mm CAT. NO. RD3485
Dark resistance: 0.5M ohm min.
Light resistance: 2.8K ohm min 8.4K ohm max.

The Jaycar supply another kind of the LDR: light resistance is 48K to 180K.

so we use the RD 3485:

One of thing confuse us is the relay:

From the diagram we can they use the Eight pin relay, six for the two lights high beam and low beam switch, we though just using a five pin relay to be a test.

We thought we can the two lights parallel together, and use one brake/park light to be the high beam and low beam.

High beam:  brake light

Low beam:  park light

The week two for the technology Project.