Injector Circuit Board Write-Up

Injector Circuit




























































Parts Lists

• Vero Board
• Jumper wires x4
• R1 resistor 470R x2
• R2 resistor 47R x2
• Transistor NPN type BC 547 x2
• LED 1 2.02volts 5mm 30mA Yellow
• LED 2 2.02volts 5mm 30mA Clear but red when it lights up

Calculation for resistors used in this injector circuit

R1 = 12/0.03mA

= 400 ohms

Therefore preferred value is 470 ohms resistor

R2 = 5 - 0.7

= 4.3

4.3/110= 39.09

Therefore preferred value is 47 ohms resistor

How the circuits works

To begin with, the 12V power supply is needed to connect to the red lead (positive) and the black lead (negative) to the circuit as a constant power supply, the LED will not just light up with the 12V power supply there is additional power added to the circuit which is input of 5V to the yellow lead which allows the first LED to light up this happens when the transistor gets the power to close up so it completes the circuit and LED lights up. The same principle is applied to the white lead which allows the second LED to light up. Therefore the user can switch the 5Volts power to yellow lead and to the white LED to allow the light to glow at each time.

Test Procedure

Inorder to test the circuit you must have 12volts power supply and additional 5volts power supply. Both of the negative leads should be connected to the negative input of the circuit. Connect the 5volts wire to the yellow wired input to let the yellow LED light up and you can also use the same 5volts wire to connect to the white input wire which will allow the second LED to light up.

Fault Finding

After making the circuit I connected to 12volts power including my 5volts my first LED did light up whereas my second LED did not light up I checked my components with the volts meter as a result I got to know that my second transistor was a manufacturers faulty good, therefore when I replaced with the new transistor all the components and circuit worked.

Reflection

If I was to re make this injector circuit one thing I would improve is that ill check all my components to ensure that they are working and safe to use.