## Dark-detector LED

The heart of this project is a photoresistor. A photoresistor is a type of resistor with resistance varying according to the light that strikes its surface. The project’s result is a LED which is automatically turned on when the lights go off.

## Objective

The project is an introduction to photoresistors.

• You see how breadboards, resistors, photoresistors, transistors and LEDs look like .
• You understand how breadboard works.
• You understand the difference between schematic and real circuit.
• You understand that sensors are input devices.
• You understand what a photoresistor does.
• You can notice a role for transistors.

## 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

• The transistor works as a variable resistor controlled by current. It lets current to pass from collector to emitter according to the current that flows from base to emitter.

## AND logic using NAND gates

AND logic is a basic digital logic. There is a specific gate for this logic, the AND gate. An AND gate gives a digital HI output only when all of its input are HI. The result of the project is digital circuit using NAND gates that implement the AND logic. A LED turns on only while both the two buttons are pressed.

## Objective

The project is an introduction to digital circuits.

• You see how breadboards, resistors, push buttons, ICs and LEDs look like.
• You understand how breadboard works.
• You understand the difference between schematic and real circuit.
• You understand the difference between digital logic and digital gates.
• You can notice a way to create digital HI/LO signal.
• You understand the AND logic.

## 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

• The NAND gate is called universal gate because using only NAND gates is possible to get any digital function.

## NOT Logic using NAND gate

NOT logic is a basic digital logic. There is a specific gate for this logic, the NOT gate. This gate is also called Inverter. An Inverter gives a digital HI output when its input is LO. When its input is HI then its output return a digital LO.

## Objective

The project is an introduction to digital circuits.

• You see how breadboards, resistors, push buttons, ICs and LEDs look like.
• You understand how breadboard works.
• You understand the difference between schematic and real circuit.
• You understand the difference between digital logic and digital gates.
• You can notice a way to create digital HI/LO signal.

## 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

• The NAND gate is called universal gate because using only NAND gates is possible to get any digital function.

## Meet the 7-segment display

Displays convert electrical signals to visual representations that have meaning to people. The 7-segment display is a simple device to display numbers or even some characters. The project’s result is a 7-segment display set to display the capital character ‘E’.

## Objective

The project is an introduction to displays.

• You see how breadboards, resistors, and 7-segment displays look like .
• You understand how breadboard works.
• You understand the difference between schematic and real circuit.
• You understand what a 7-segment display does.

## 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

• Every segment consists of a LED.
• Resistors role is to reduce the current to prevent and damages to the LEDs.
• By turning on a selected group of segments, a specific number or character is displayed.

## 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.

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 two LEDs connected to its output. The two LED blink alternatively 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 in action.  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

• The resistors which are in series with the LEDs has nothing to do with the charging/discharging the capacitor. So, it has nothing to do with the blinking frequency. Its role is to reduce the IC’s output current to avoid any damages to ICs or the LEDs.
• You can change the frequency of the blinking by using different capacitor or different resistors which are evolved in capacitor’s charging/discharging. For example use a capacitor with more capacitance and you will get a slower blinking.

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.  