MULTIMETER:
Multimeter is used to measure different parameters like voltage, current, resistance, etc... by setting the dial at a proper position.
A very important feature of multimeter is continuity test-used for debugging ckts.You can check if the circuit connections are proper as per the circuit diagram.
It is a good habit to check continuity of every new connection while making the circiut on a board else it becomes difficult to find any continuity error at the end.
A cheap n best multimeter(yellow ones) used generally by the students is shown below.
NOTE:connect the multimeter in parallel to measure voltage and in series to measure current.
DIODES AND LEDS:
Diodes are two terminal devices which conduct electricity in one direction.
LEDs contitute an important element of digital ckts-used to display output as a monitor shows the output of a c program you execute in your computer.
LED has two leads- cathode and anode.They are identified by the length of the lead.Cathode lead is of lesser length.However this is not a reliable identification, for confirmed identification see the figure below:
Connect LED to the output of any IC with a resistor in series.LEDs have a small resistance,so a resistor in series decreases the loading effect of any output.If you connect the output of 7805 directly to an LED then the voltage output of 7805 reduces to 3.85V from 5V.
Relays
a relay can make a 5V DC signal from a circuit output to switch a 230V AC mains circuit. The input section has a coil which generates magnetic field when a small voltage from an electronic circuit is applied to it. This voltage is called the operating voltage. Commonly used relays are available in different configuration of operating voltages like 5V, 9V, 12V, 24V etc. The output section consists of contactors which connect or disconnect mechanically. In a basic relay there are three contactors: normally open (NO), normally closed (NC) and common (COM). At no input state, the COM is connected to NC. When the operating voltage is applied the relay coil gets energized and the COM changes contact to NO. Different relay configurations are available like SPST, SPDT, DPDT etc, which have different number of changeover contacts. Figure given below shows how a relay basically operates.
Multimeter is used to measure different parameters like voltage, current, resistance, etc... by setting the dial at a proper position.
A very important feature of multimeter is continuity test-used for debugging ckts.You can check if the circuit connections are proper as per the circuit diagram.
It is a good habit to check continuity of every new connection while making the circiut on a board else it becomes difficult to find any continuity error at the end.
A cheap n best multimeter(yellow ones) used generally by the students is shown below.
DIODES AND LEDS:
Diodes are two terminal devices which conduct electricity in one direction.
LED has two leads- cathode and anode.They are identified by the length of the lead.Cathode lead is of lesser length.However this is not a reliable identification, for confirmed identification see the figure below:
Connect LED to the output of any IC with a resistor in series.LEDs have a small resistance,so a resistor in series decreases the loading effect of any output.If you connect the output of 7805 directly to an LED then the voltage output of 7805 reduces to 3.85V from 5V.
Relays
a relay can make a 5V DC signal from a circuit output to switch a 230V AC mains circuit. The input section has a coil which generates magnetic field when a small voltage from an electronic circuit is applied to it. This voltage is called the operating voltage. Commonly used relays are available in different configuration of operating voltages like 5V, 9V, 12V, 24V etc. The output section consists of contactors which connect or disconnect mechanically. In a basic relay there are three contactors: normally open (NO), normally closed (NC) and common (COM). At no input state, the COM is connected to NC. When the operating voltage is applied the relay coil gets energized and the COM changes contact to NO. Different relay configurations are available like SPST, SPDT, DPDT etc, which have different number of changeover contacts. Figure given below shows how a relay basically operates.
