4841 Transistor

P= P-type (hole)             A= Anode
N= N-type (electrons)    K= Cathode


DIODE

TRANSISTOR

A transistor is a component used to amplify and/or a switch by using small electric signals.

NPN= Not Pointing In
PNP=Point iN Plz


How it works
To work as a amplifier a high voltage can be pass through the collector (input) and emitter (output) the base is the switch a voltage less than 1v can be use (but not more than 15v or else the transistor will over heat and melt) when base gets a signal, this allows voltage to pass from collector to emitter this acts as a amplifier. 
You can also get transistors that will turn off when base gets a signal these are PNP type transistor.


How to test
Tools need :multimeter on diode test 
There are six positions you should place with your multimeter probe to get a conclusion.
Like a diode, current will only go one way the leg that gives a reading with the two other leg is the base. now that you have found base next is to find emitter, keep one probe on base and with the other test the other two leg and the highest reading out of the 2 leg is the emitter.

4841 Switches and Relay

What is a switch use for
A switch is basically use to make or break a circuit


Switch Electronics abbreviation
SPST = single pole, single throw 

SPDT= single pole,double throw

DPST=double pole,single throw

DPDT=double pole,double throw

Relay
Relay is a switch that operates electrically.

How it works
Picture on the right. The top spring is connected to a leaver that holds it connected to the outer right leg, when voltage is pass through the coil it creates a magnetic field when the correct voltage passes through the coil  (you can buy relay that responds to 6v or 12v) the magnet gets strong enough to attracts the armature and the leaver which connects to the middle leg, depending on how you connect the relay to the circuit this make or breaks the circuit.






http://en.wikipedia.org/wiki/Relay

85  Negative coil 

86  Positive coil

30,87  Terminals Switch normally open (NO)

30, 87A   Terminals Switch normally closed (NC)

85  Negative coil 

86  Positive coil

30,87  Terminals Switch normally open (NO)

Relay with diode

On some relays there is a diode build in to protect circuit components from back EMF (electromotive force)  produced by the relay coil a diode is installed next to the coil.

Car alarm Signal light

Four 4 pin relays switching electric window motor by Roman B

Two 5 pin relays switching electric window

4841 Resistor

What is resistor use for 
Resistor is used in a circuit to restrict the flow of current and the amount of restriction is measured in ohms (Ω)


Resistor Groups and what they mean
E12   10% toleranceE24     5% toleranceE48     2% toleranceE96     1% tolerance


E12 Resistor Group
       say as         say as         say as           say as       Replace the decimal point with R or if its Kilo use K
1.0 =1R     10 =10R    100 =100R    1000 =1K
1.2 =1R2   12 =12R    120 =120R    1200 =1K2
1.5 =1R5   15 =15R    150 =150R    1500 =1K5
1.8 =1R8   18 =18R    180 =180R    1800 =1K8
2.2 =2R2   22 =22R    220 =220R    2200 =2K2
2.7 =2R7   27 =27R    270 =270R    2700 =2K7
3.3 =3R3   33 =33R    330 =330R    3300 =3K3
3.9 =3R9   39 =39R    390 =390R    3900 =3K9
4.7 =4R7   47 =47R    470 =470R    4700 =4K7
5.6 =5R6   56 =56R    560 =560R    5600 =5K6
6.8 =6R8   68 =68R    680 =680R    6800 =6K8
8.2 =8R2   82 =82R    820 =820R    8200 =8K2


Colour code
http://www.ohmslawcalculator.com/resistor_color_chart.php

How to calculate resistance in a

Parallel Circuit

1/RT=1/R1+1/R2+1/R3....

Series Circuit

RT=R1+R2+R3......