Week 5

Educational " Metal, Nonmetal " detector

My task this week is to create a small electrical circuit, I will build a small basic circuit for educational purposes to help kids know the difference between metal and nonmetal materials, it will have a light indicator and buzzer when it is connected with metal.

I'll use the Tinkercad web app to simulate and test the circuit before building the prototype with cardboard

To know how I did it, follow me to the next few steps.

• Navigate to the Tinkercad website.

• Sign up for a new account “You can choose to log in directly with your Gmail account.”

• After creating your account, log in to your dashboard and you will find it as shown.

The application interface will look like the top picture

From the search box “search and drag and drop the component of the electric circuit “
- power supply, LED, resistor, buzzer, slide switch, breadboard

The wire will be inserted later from the toolbar.

By clicking each device you can change its properties

as you can see, from the top toolbar you can rotate the objects or press "R" and mirror objects with polar or press "M".

Also you can draw wires and choose their colors

🔴Important note about the breadboard

The breadboard has two sections.
- One for the power framed in red and connected in one line as shown in green dots, one for the negative and one for the positive.
- The other section which is framed in yellow is for the other circuit component and connected in one line as shown in green dots.

set the Voltage to 5V

set the resistor to 220 Ohm

You can choose your LED color too

The LED has two polar called “Anode connected to the positive pole of the battery and the cathode connected to the negative pole of the battery “

Now let's build the circuit simulations

let's start with the circuit component as shown

DC 5V Power supply
small Buzzer
slider switch
3 resistors 220 Ohm
Yellow LED for power indicate
Red LED to indicate when testing objects
Potentiometer " 250K Ohm " to be used as a test device
Small breadboard
some wires as jumpers

📚Why did we choose 220 Ohm for the resistor and 5-volt adaptor?

from the standard LED datasheet, I found that the default current for it is 20 mA and the power supply provides 5 V

by applying Ohm law " the resistance = voltage/current " = 5V/0.02A=250Ohm, the nearest real physical for this number is 220 Ohm

and I used 5-volt adaptor because all components work on 5 or less, and more than that can burn the components.

for the 3 V buzzer after reviewing the data sheet it works on voltage from 4: 8 volts so it's ok if I don't use a resistor for connecting the buzzer.

First, we will build the basic circuit as a series connection from the Power supply, yellow LED, resistor, and slide switch, I used a series connection to make same current flows through all components

Let's test our circuit by Pressing the start simulation, perfecto👌🏽

Now let's build the test circuit, using the red LED and the buzzer with the 220 Ohm resistor, this circuit will be parallel connected with the power circuit, and I'll use the potentiometer as a test device to test the circuit, I used the parallel connections to make sure all components get the same voltage.

As you can see in the picture when we ran the simulation, we turned the potentiometer to 0 Ohm the red LED indicated and the speaker buzzing, and when we increased the resistance they turned off

Now the circuit is done and the simulation is working perfectly

let's go to the next part, Implementing the physical circuit

I used cardboard, cutter, cutting pad, ruler, gule gun, and adhesion tape to build it

Let's get the components

Build the power circuit

Complete the circuit as we designed it on tinkercad

Test 1.mp4

working perfectly

At this stage, I'm gonna build a nice small cardboard housing for the circuit with size

9cm L, 5cm W, 3cm H

I made some places for power adaptor" 5v Power adaptor ", buzzer, and LEDs

and small red switch

I found Banana To Alligator Clip at the free electronics store with a female banana jack it will fit perfectly for the device and it can hocked easily with tested material.

I will install it at the front of the cardboard