Night Light
Green & White

The fun didn't stop there when I recevived a huge wad of LED lights from Brightsparks. So far, I had put them in my computer (see 'Computer Power LED upgrade').

I also had a flash light which was capable of a quick switch so I could change the colour of the LEDs by ripping them out and putting another one in (see 'LED Flash light').

So what next?
Well, since moving up to Christchurch we (more like my brother!) have been quite reliant on a night light. The model we used was a:
 

ARLEC CS96341V NL900/S1
240V AC
7 W max

Equipped with an LDR (the black dot - the middle bottom), the Cadmium Sulphide LDR made it so that, when there was sufficient light, the night light would turn off, and when there was no light / insufficient light the night light would activate and turn on. Smart eh?

This circuit can be reproduced, this is pretty much all there is to it:


Transistor, LDR and Light pretty much.

I made this circuit on a breadboard. But the results weren't satisfying... under sufficient light, the light would still turn on... despite hours and hours of tweaking, I still couldn't get it perfect. So I just flagged it.
Instead I used a 4xAA switched battery box from DSE. $2.06 - not bad. Using an IC holder vero-board, it was great for a board for me to work on. 2 for $4 - sorta expensive... I decided to make this project because overtime the bulb night light would prove to be really expensive due to it's high electricity drain (we leave it on all night remember!).
 


This is the circuit diagram.
The things enclosed in the dotted box is the 4 way battery holder



These are the IC veroboards. Because the circuit is so simple I decided to use the hacksaw to cut them up :)

After about 5 minutes of soldering etc, the night light complete with it's own switch was COMPLETE!
 


As you can see this is the green night light. It is made for the hallway


This is the white night light for the kitchen as this too was really dark at night. This night light is white although it looks bluish.

Mission Successful?

I'd have to say yes actually. Let's compare the effeciencies of the two night lighting options:

Artec Night Light:
Power = 7W

1x LED Night Lights:
Voltage = 4.5V
Current = 30mA
Power = 0.135W
Because I have two of these lights I will multiply the power consumption by 2.
Total Power = 0.27W
% of Power of Arlec = (0.27 / 7) x 100 = 3.86%
The two LED lights together only use 3.86% of the power of the Artec Night Light = Power saved.

I can't exactely compare the two, although the Arlec one provides more light, the single LED night lights still provide enough light so you can see the hallways etc. Projecht successful.

This conculdes the projecht of:
Night Light
Green & White