* a simple led triggered by 1.4 volts
* a PNP transistor (in this case the 2N3904)
* The component are in the green box
[[File:Green_box.jpg|600px]]
Yes, This green box !!
== How to ==
The circuit is as followed :
The bread board can be assembled as followed.
[[File:Joule_Bread.jpg|600px]] And the resulting voltage on the side on the led should like like [[File:Joule_oscillo.jpg]][[File:Green_box.jpg|600px]]
== What is happening there ? ==