Electronic Candle

We'll start with an easy and fun project. Amaze your friends with this bit of electronic magic. You can "blow out the Lamp". The "candle" (Lamp) will come on when you let light shine on the CdS cell, when the light is removed from the CdS cell, the "candle" Lamp) goes out.

It is most effective when you use a match for the light, though you can also use a flashlight or other light source. Of course there is a trick to it, but if you don't tell anyone the secret, it can sure keep them guessing a long time. Basically what is happening is that the light level is low enough that until the Lamp in this kit is ON, there is not enough light to turn on the Relay to power the Lamp.

Use the CdS Light Shield with this experiment. In detail this is how you get it to work. First make sure the surrounding light is not bright. Use the excuse that you don't need a candle if the light is already bright enough.. Now adjust the 5OK Control up to the point where the circuit is about to turn ON the Lamp (a little practice is needed for this).

At this setting a little additional light from a match or flashlight will turn the Lamp ON. With the additional light from the Lamp the match or flashlight may be taken away and the Lamp will stay ON.

The second trick is to "blow the candle out". To do this, cup your hand around the "candle" to blow it out "gently". Now just as you blow with your mouth, move your hand slowly between the light and the CdS Cell. The shadow of your hand will remove enough light to allow the Lamp to go out. Once the Lamp is out it takes additional light from another source to get it on again.

Now go to it, but remember, it's our secret.