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Picture of Sensor LED Flashlight (9v, with light / dark detector video)
This instructable is about making an LED flashlite with light / dark sensor. it turns on automatically when its dark and turns off when its day.

Step 1: Step 1: Collect the parts:

Here's what you will need:

1. LDR (Light Detecting / Dependent Resistor)
2. NPN Transistor (I have used BC 547)
3. 9 volt battery
4. 9v battery lid
5. Four LEDs, 5 mm bright white
6. 1/4 watt, 100 ohm resistor (per LED, so 400-500 ohms for 4-5 leds)
7. 1/4 watt, 10k ohm resistor (per led)
8. small piece of PCB to mount the assembly.

Note: Instead of items 6 & 7, you can straightaway use a single 500 ohm & 50K (or 100k) resistor each, if you are going to use only 4 or 5 leds....

Additional tools like, solder, solder wire, hot glue or its equivalent.

 
Dipankar5 years ago
Your idea is good but your Photographs needs a lot of improvement.
amando965 years ago
 very nice, you could plug it to a 9v transformer so it doesnt use up the battery, but then it isnt portable anymore...