You have to like this very simple
. .... Only Four Components
including the Light Emitting Diode.
Still the circuit is worth bread boarding before publicationCircuit Operation ;
See the circuit diagram. A normal DC wall wart has a 3' to 4' foot cord and as such
it is good practice to put a capacitor at the far end where the regulation occures, to avoid micro power drop outs.
The LM317 and 68 ohm resistor make a standard constant current regulator that is set
to about 20 milliamps in series with any LED.The Components ;
- One White LED of your choosing.
- One LM317LZ Regulator TO-92
- One 68 Ohm 1/8 Watt Resistor.
- One Tantalum 22uF to 47uF 25V Capacitor.
- A small Wall Wart ( 5V to 24Volt DC output )
- A matching Coaxial connect Receptacle.
You may use a TO-220 regulator as well as the smaller TO-92 package.
See a cluttered electronics work bench ( No clear level surface:)
I used the smallest Wall Wart which has a ( 6Volts DC Output capable of 200 ma ) and
a Coaxial delivery plug