Circuit Board #2

Circuit Board #2

Construct a circuit, that simulates a Voltage Regulator

This circuit represents a 5V output from an ECU used to signal the fuel injectors.

To calculate resistance needed;

[ Vs - LEDv ] / I

= [ 5 - 1.7 ] / 0.02

= 3.3 / 0.02

= 165 ohm

Thus establishing the a 180 ohm resistor used as R1. If R2 = 240 ohm (data sheet specification) then;

Vout = Vref (1 + R3 / R2)

= 5 = 1.25 (1 + R3 / R2)

= 5 / 1.25 = 1.25 / 1.25 (1 + R3 / R2)

= 4 - 1 = R3 / R2

= 3 = R3 / R2

Meaning R3 is 3 x R2;

R2 x 3 = R3

= 240 x 3 = 720

So R1 = 180 ohm, R2 = 270 ohm and R3 = 820 ohm

Components:

1x LM317 Voltage Regulator

1x LED

2x 1N4007 diodes

1x Zener diode

2x 1uF capacitors

1x 180 ohm resistor

1x 270 ohm resistor

1x 820 ohm resistor

Again using Lochmaster to create a circuit board design. Gives a great range of components.

If u hadn't noticed (and I didn't) the underneath of D4 (the black diode above) has not been cut, therefor it is being shorted, and defeats the purpose of even having one. At first my voltage regulator was not working, but Scott was quick to help and point this out.

After a long fluff around I got the board to produce a just less than average result;

Regulated Voltage = 5.9V

Voltage drop readings;

Regulator:

Input to Output = 6V

Input to Adjust = 7.3V

Adjust to Output = 1.25V

D13 = 0V

D12 = 6.05V

D15 (Zener) = 12V

LED = 4.3V

R1 = 2V

R2 = 1.25V

R3 = 4.66V

C16 = 5.9V

C15 = 12V

The reason for less than perfect result i suspect, is because of a resistor being too high. Either R2 or R3. Never the less, the concept is present.