Some Explanations About Robot Electronics

Below are brief explanations of some of the parts used within the robots:

Resistor
A Resistor is an electronic component that is deliberately designed to restrict the flow of electrical current in a circuit. The higher the resistance value, the more it restricts the flow. The resistor will give the circuit a stable current thus giving protection to sensitive elements within a circuit from damage. The resistor is measured by its ability to offer resistance and this is defined in “Ohms”.

What is Ohms Law?
The Law basically brings together the relationship between Voltage (V), Resistance ( R) and Current (I) as follows:

Resistance (R) (ohm W)	=	Potential Difference (V) in volts
		Current (I) in amperes

The official definition is: A resistor offers a resistance of one ohm Ω if a potential difference of one volt drives a current of one ampere through it.

What's an ampere?  
The unit for current, the symbol for the ampere is (A).

What's Potential difference?  
Potential difference is a difference in electrical potential energy across each resistor and across a battery.

How do you determine the resistance of a resistor?
Resistors are colour coded for easy reading. To determine the value of a given resistor look for the gold or silver tolerance band and rotate the resistor as in the photo above. (Tolerance band to the right). Look at the 1st colour band and determine its colour. This maybe difficult on small or oddly colored resistors. Now look at the chart and match the "1st & 2nd colour band" colour to the "Digit it represents". Write this number down. Now look at the 2nd colour band and match that colour to the same chart. Write this number next to the 1st Digit. The Last colour band is the number you will multiply the result by. Match the 3rd colour band with the chart under multiplier. This is the number you will multiple the other 2 numbers by. Write it next to the other 2 numbers with a multiplication sign before it. Example: 2 2 x 1,000. To pull it all together now, simply multiply the first 2 numbers (1st number in the tens column and 2nd in the ones column) by the Multiplier.

Resistor Colour Code Chart
1st & 2nd Colour Band	Digit it Represernts	-----Multiplier-----
BLACK	0	X1
BROWN	1	X10
RED	2	X100
ORANGE	3	X1,000 or 1K
YELLOW	4	X10,000 or 10K
GREEN	5	X100,000 or 100K
BLUE	6	X1,000,000 or 1M
VIOLET	7	Silver is divided by 100
GRAY	8	Gold is divided by 10
WHITE	9	⋅Tolerances ⋅Gold = 5% ⋅Silver = 10% ⋅None = 20%

Capacitors
There are several types of capacitors but they all perform the same basic function; that is to store electric charge. Used in electronic circuits; it consists of two or more metal plates separated by an insulating layer called a dielectric. Its capacitance is the ratio of the charge stored on either plate to the potential difference between the plates. The SI unit of capacitance is the farad, but most capacitors have much smaller capacitances, and the microfarad (a millionth of a farad) is the commonly used practical unit. Electrolytic and Mylar capacitors are used in this electronics kit. We use a combination of resistors and capacitors to suppress voltage fluctuations in the power supply and set the time period on the timer. Capacitors can also be used to remove any alternating current components within a circuit.

Mylar capacitors have an insulator, which is a flexible mylar film, so a large area can be rolled up into a compact package. They do not have a polarity. Capacitors with large values are usually electrolytic. They have a polarity (or direction) and are sensitive to levels of voltage.

SI unit (symbol F) of electrical capacitance (how much electric charge a capacitor can store for a given voltage). One farad is a capacitance of one coulomb per volt. For practical purposes the microfarad (one millionth of a farad, symbol mF) is more commonly used. The farad is named after English scientist Michael Faraday.

Transistor
A transistor is a semi-conductor with the ability to amplify current. Transistors commonly consist of a tiny sandwich of germanium or silicon, alternate layers having different electrical properties because they are impregnated with minute amounts of different impurities. A crystal of pure germanium or silicon would act as an insulator (non-conductor). By introducing impurities in the form of atoms of other materials (for example, boron, arsenic, or indium) in minute amounts, the layers may be made either n-type, having an excess of electrons, or p-type, having a deficiency of electrons. This enables electrons to flow from one layer to another in one direction only.

Each transistor has three terminals called the Emitter, Base and Collector.  When current flows into the base the emitter or the collector changes the current to a higher level.

We use the transistors in this robot to turn on the LED into a pulse form. We also use them to control the rotating director of the left motor. The transistors amplify the signal from the sensor to rotate the motor and could also be used to cause the LED to flash.  

Diodes
The diodes used in this circuit allow the flow of electrons one way only. This flow is from the anode to the cathode. Therefore, diodes are basically a one-way valve for electrical current. They let it flow in one direction (from positive to negative) and not in the other direction.  Most diodes are similar in appearance to a resistor and will have a painted line on one end showing the direction or flow (white side is negative). If the negative side is on the negative end of the circuit, current will flow. If the negative is on the positive side of the circuit no current will flow.

Microphone
The microphone is used to pick up the sound or vibration signal and convert it into an electrical signal. It is a type of Field Effect Transistor (FET). The Sound Tracker robot uses a condenser microphone as the sensor for detecting the sound of the robot hitting an obstacle or the sound of your hands clapping.

Integrated Circuits
Integrated Circuits, or ICs, are complex circuits inside one simple package. Silicon and metals are used to simulate resistors, capacitors, transistors, etc. It is a space saving miracle. These components come in a wide variety of packages and sizes. You can tell them by their "monolithic shape" that has a ton of "pins" coming out of them. Their applications are as varied as their packages. It can be a simple timer, to a complex logic circuit, or even a micro-controller (microprocessor with a few added functions) with erasable memory built inside. The IC’s used in this robots amplifies the output voltage from the sensor and these signals to the circuit controlling the left motor. Basically it is amplifying the weak signals from the light sensor or phototransistor, and sends them to the motors for controlling the robots movements.

Email:
sales@iBotz.com