LED have a fixed voltage drop regardless of the current draw, so must be provided with a ballast resistor when driven from a voltage source. As an alternative, this project uses a voltage regulator arranged as a current sink. It is flexible for the current and the supply voltage. An application is shown for three high-power white LEDs connected in series, using a 15-Volt supply.
The current regulator is turned on or off by a Picaxe microtroller, so that the LEDs are only on during the evening.
|Here are photographs
Here is the circuit diagram
|Here is the code