power circuit

     Circuit diagram 

           A component list

     2x1n4007 Diode

     2x capasitor 33mF  

     1xZener diode 

     1x voltage regulator LM317

     1xR1

     1xR2

     1xR3

     1xLED
1x PC Boards Vero Type Strip

Calculations

           Calculate the values of R3,R2

           Vref=1.25 

           Vout=5v

           Use Vout=Vref (1+R3/R2)

               5 = 1.25(1+R3/R2)

       5/1.25 = 1+R3/R2

               4 = 1+R3/R2

          4 - 1 = R3/R2

               3 =  R3/R2

             R3 = 3 x R2

This mean that R3 is 3 times bigger than R2, So we were given 330R for R2 and 1K resistor for R3.

For R1: LED resistor

    R1 =   (V_S - V_L) / I

    R1 =  (5-2.1)/30

    R1 = 100 R

Lockmaster

      A Technical Explanation 
     This is a normal voltage regulation circuit. As the raw 12V is presented into the circuit, it goes through the diode (These diodes 1N4001 is to  prevent back EMF) using  0.7V so 11.3V goes into the regulator  (The regulator is a LM317T) which is then stepped down to 5V. C1 and C2 are 33 mF , the capacitors job is to  provide stability in the output voltage .The 2 zener is a 2V2 zener. . The R1 100R with the LED is a indicator to tell if there is voltage going through the circuit. R2 is 330 R and R3 is 1 K, R2 and R3 are used to determine how much voltage output will be. 

      Test Procedure 
 12V to the input  and out put should be 12v on the red wire and 5v on the yellow wire and black to ground (negative)

      Reflection 
I wouldn't do anything different if i was to build the circuit again. as my circuit worked  first time, so i dont see how i could make a different. 

   

      Finish result