LED Throwies.. All Kinds

I plan to make all kinds of throwies..

I have made 2-3 kinds..

so lets begin:

1) The simplest ones are the always-on led throwies with a magnet and a Li 3V cell.. which dnt last more than a week..

I put this kind (a blue LED) behind a sketch of a doll.. just behind her hair.. which give a nice diffused glow at night..

2) But the always on kind dnt seem to be a very good idea.. So I decided to make one which would glow only at night and not during daylight..

The additional ingredients for the ckt. are a phototransistor/ photodiode and a transistor and a resistor.

The circuit diagram is as shown :

Led Throwies that glow at night!
working of the circuit

Using a photodiode : (I used it as it is a cheaper option to a phototransistor)

Testing on the breadboard :

setup acc. to the diagram
breadboard testing

When the photodiode is in a bright ambiance, the  LED would glow dim; and when the ambiance is dark, LED glows bright.

So, here’s the testing:

Bright Ambiance : Low glowing LED
Photo diode covered with a black surface.. So LED shines brightly

After soldering and putting a magnet on the back, and covering up the whole thing with transparent tape, looks like this :

top view of the throwie.. resistor, transistor inside.. LED, photodiode outside

But there were issues with this one as well.. whenever a tubelight was on in the room, at night, it wouldnt detect that, and would keep glowing.. So it detects natural daylight well.. bt not other kind..

So I finally thought of making a throwie with a switch, which would glow on n off whenever u want it to..  and u dnt need any transistor or resistor etc..

n it works glows nicely! 🙂

Here is the final one..

The ckt diagram is simple, just a switch between the battery and the LED.

solder the switch with the LED
slip in the jumperson both sides of the Li battery and put gluedrops
add a small disc magnet
stick on
at night! I wore it on a steel bangle.. acts like a small torch!

So go on and Make something! 🙂


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