The Torch Which Switches Off When Its Dark! ;) My First Useful Invention




Introduction: The Torch Which Switches Off When Its Dark! ;) My First Useful Invention

Today I'll make my first instructable, it's about my first invention too. My 'torch' is sort of a joke invention that I made because I was bored. It is completely unuseful ;) The torch will turn on when it is light and will turn off when it is dark.

Step 1: Materials

The materials you need:

- A 100K potentiometer

- A LDR resistor

- A BC 547 transistor

- Maybe a resistor (I will later on tell why and what for resistance)


- Some wire

Step 2: The Circuit

The circuit is from:

I have changed some things, because I have used 2 AA batteries and no resistor (so the led in the torch gets more power.

Step 3: Soldering

Here is my PCB with all the components soldered on. With a - and + input from the AA batteries and a - and + output to the LED.

Step 4: Getting Everything in Place

As you see are the white wires the - and + input from the batteries, and the black and red the - and + input for the LED. The red and black wires are not allowed to touch some of the battery outputs, because then it will be a normal torch. So I glued some foam on the outputs of the batteries. I made a hole in the torch with my soldering iron (it's not the best for your soldering iron) so the wires could go in and out the torch.

Step 5: Finished!

And that's how you make a torch which wil switch of if it is dark! Totaly unnecesary! ;)

As you see some parts are exposed outside the torch. That is because my torch was to small. So feel free to make it completely look like a normal torch.

First Time Authors Contest 2016

Participated in the
First Time Authors Contest 2016

Make it Glow Contest 2016

Participated in the
Make it Glow Contest 2016

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    2 Discussions


    3 years ago

    Lol, this could make a fun gag gift :)


    Reply 3 years ago

    Indeed it is!