## Push-on LED

The project’s circuit is very simple. It consists of a LED (Light Emitting Diode) connected to a battery in series with a resistor and a switch. The result is a lit LED when the button is pressed.

## Objective

This breadboard project is a good starting point for the very beginners.

• You see how breadboards, resistors, switches and LEDs look like.
• You understand how breadboard works.
• You can note some really basic concepts in electronics like polarity, close circuit, Ohm’s law for the resistor value.

The project is also used by advanced makers as warming-up before they continue to more complicated things.

• It gives the message that the parts (LED, resistor, switch, cables, battery) and equipment (breadboard) have no problem so they can be used in the next project.
• It boosts you confidence and makes you ready for the next project.

## The Schematic

This is the circuit of the project.

You can see a way to set up the circuit on the breadboard. Remember, there are many correct ways to transfer a circuit on the breadboard.

## Notes

• When the button is pressed, the circuit is closed. Otherwise the circuit is open.
• As always, we assume that the current starts from the positive battery’s pin, it passes through the resistor and the LED. Current’s destination is the negative battery’s pin.
• When enough electric current pass through the LED, it makes the LED lit.
• If too much current passes through the LED, it destroys the LED. A resistor is used to reduce the current. Usually LED can handle 20mA.
• The resistor’s value selected after some math. Ohm’s law: Current=voltage/resistance. So here, current=9/470=0,019=19mA. That means the 470ohm resistor can protect the LED from being damaged by high current when using battery 9v.

## Hello Electronic World!

The project’s circuit is very simple. It consists of a LED (Light Emitting Diode) connected to a battery through a resistor. The result is just a lit LED. This circuit can be considered as the analogy of  “Hello World!” programs in software development .

## Objective

This breadboard project is a good starting point for the very beginners.

• You see how breadboards, resistors and LEDs look like.
• You understand how breadboard works.
• You can note some really basic concepts in electronics like polarity, close circuit, Ohm’s law for the resistor value.

The project is also used by advanced makers as warming-up before they continue to more complicated things.

• It gives the message that the parts (LED, resistor, cables, battery) and equipment (breadboard) have no problem so they can be used in the next project.
• It boosts you confidence and makes you ready for the next project.

## The Schematic

This is the circuit of the project.

You can see a way to set up the circuit on the breadboard. Remember, there are many correct ways to transfer a circuit on the breadboard.

## Notes

• This is a permanent close circuit.
• As always, we assume that the current starts from the positive battery’s pin, it passes through the resistor and the LED. Current’s destination is the negative battery’s pin.
• When enough electric current pass through the LED, it makes the LED lit.
• If too much current passes through the LED, it destroys the LED. A resistor is used to reduce the current. Usually LED can handle 20mA.
• The resistor’s value selected after some maths. Ohm’s law: Current=voltage/resistance. So here, current=9/470=0,019=19mA. That means the 470ohm resistor can protect the LED from being damaged by high current when using battery 9v.

## Ohm’s Law

The power source V, leads electric current I through the resistor R. Thus we can say that the three quantities obey the law of Ohm.

Ohm’s Law relates the voltage (V), the current (I) and resistance (R).

Ohm discovered that the current in a circuit is directly proportional to the voltage applied to the edges of a circuit and inversely proportional to the resistance of the circuit.

V = I x R

This relationship can be expressed in three ways:

I = V / R

R = V / I

V = I x R

where:

V    = voltage (Volts)

I     = current (Ampere)

R    = resistance (Ohm)

The corresponding relationship between units is: Ampere = Volts / Ohm

Thus in a given circuit, the voltage and the current are proportional to each other. This implies that if we double the voltage across the circuit, the current will be doubled; the higher the voltage, the greater the current. However, if we double the resistance of the circuit, the current will reduced by half; the greater the resistance, the less the current.

So by applying the relation V = I x R, if we know any two of the three quantities, we can find the third.

According to Ohm’s law if it is applied potential difference of 1 Volt to the edges of a circuit having a resistance of 1 Ohm, will be generate a current of 1 Ampere.

This is a classic project. The IC (Integrated Circuit) NE555 is around and popular for many decades. Its main application is to form oscillator circuits. This project is about creating an oscillator with a LED connected to its output. The result is a LED which is blinking in constant period.

## Objective

The project is an introduction to oscillator circuits and to ICs.

• You see how breadboards, resistors, capacitors, ICs and LEDs look like.
• You understand how breadboard works.
• You understand the difference between schematic and real circuit.
• You understand what an oscillator does.
• You can note that the function of an oscillator based on the charging-discharging cycle of a capacitor.

## The Schematic

This is the circuit of the project.