Circuit 2:
Components:
- 1 x Zener Diode
- LM317 Voltage Regulator
- 2 x Rectifier Diodes
- 2 x 100uF 16V Electrolytic capacitors
- 3 x Metal Film Resistors
- 1 x LED
Operation:
The purpose of this board is to regulate the voltage coming in ( 12 V) and have a 12V and a 5 V coming out of this circuit , the voltage needs to be around 5 V and it also needs to be stable .
Calculation:
This circuit uses 3 different resistors ...R2 and R3 are for regulating the voltage coming out of our voltage regulator and R1 is to regulate the voltage for our indicator LED.
so we use the formula given to us :
Vref = 1.25 V
Vout = 5 V
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
so this is the ratio between the resistor R3 and R2 , wat ever R2 is R3 is 3 times larger so if R2 =250 Ohms R3 = 750 Ohms But I 've looked up on the internet to find out the resistance of these two resistors and they are 820 Ohms for R3 and 270 Ohms for R2.
to find out R1:
R = V / I
R = ( 5 - 1.8 ) / 20 mA
R= 160 Ohms
So after doing the caculations this is the board I desighned using Loch master 3.0
I did come up with a problem and by doing Voltage drop I checked my board and found out a part of the track on my board was damaged due to too much heat of solder and it there was no continuity after D13 and input terminal of my voltage regulator , It was suppose to be around 11.3 V but because of the broken track it only had 0.235 V so I rectified the problem by soldering a piece of wire over the broken part of the track and after that it was working ...
What I learned from this part is not use too much heat on the board which can damage components and the board itself .
After fixing this problem I manged to get a reading of 4.95V but after putting it inside my bag and kinda squashing it I gotte a reading of 4.47V , by this time I've spent too much on this board and started to fall behind on the third board so I moved on .
