Power Circuit

Components list

R3= 330R (0.6W)

R2=100R (0.6W)

R1=100R (0.6W)

C15 and C16= 33 micro farad. (25V)

D13and D12= Diodes (1n4001) (1A, 50V)

D15= Zenor diodes

Regulator LM317.

Red l.e.d (30mA, 1.8V)

To calculate R1 i used the formula R=(Vs-Vled) / I

= 5-1.8/0.030= 106.6 Ohms. I used the preferred value of 100 ohm.

To calculate R2 and R3 i rearranged the formula Vout=Vref (1+r3/r2)

Vref= 1.25V, Vout=5V

To Vout/Vref -1 = R3/R2.

So 5/1.25=4.

4-1=3.

3= R3/R2

3 is the ratio. R3 must be 3x larger than R2. This is why i used 330ohm and 100 ohm resistors.

The circuit is a voltage regulator with 12V entering the circuit and 5V leaving. R3 and R2 adjust the regulator voltage because they connect to the adjust leg of the regulator. The l.e.d will emit light if there is voltage leaving the regulator. There should be 5v after the output leg of the regulator. The l.e.d shows if the output circuit is working. The capacitors are filters. D12 is to protect the regulator. It protects the regulator by stopping the 12v connecting to the output. The zenor diode is in reversed bios. This will drop voltage to X volts of the zenor before the input leg of the regulator.. All the circuit needs to work is the regulator and the resistors the rest of the components are optional. This circuit could be used at any time when you have a 12v input and require 5v for a component or circuit.

Test procedure.

Check if l.e.d is emitting light. There should be 12 at the input of the regulator and 5v at the output. There should be also 5v at the wire before the l.e.d There should be 12v at the 12v output wire. Test the output wires they should read around 5V. My circuit ended up having 5.2V across the output which is acceptable for this power circuit.

Problem solving.

First problem i had was it was shorting. I think this was because i didn't have my holes drilled correctly. I ended up taking the circuit apart and re drawing it on lochmaster. It then worked.I had 5.2V on the output. If i was to do the circuit again in the future i would double check everything before i soldered it to the board. Also i would be more careful when cutting the board I ended up with a little crack in the board. I did end up moving a resistor from the above drawing.