Experiment #7

Transistor in A Circuit

Components: 1x small signal NPN Transistor,

2x resistors.

I connected the multimeter between the base and emitter giving me a reading of 0.75V about the same as the diode test it only lets that amount of voltage through but does also have a small amount of amps i got 0.9mA

These are the regions that the transitors works and what they are cutoff is where there is little electron flow through the connections. active is where electron flow can vary quite a bit but when in saturation the switch is fully turned on. Also varying the voltage of the transistor you can change the amount of beta.

Experiment #6

Transistors

This is how i checked the BJT's to find which probes were the base, emitter and collector using a multimeter in the diode check modes with no voltage running through the transistor.

These are the readings you should get when teating each transistor to tell which is the NPN transistor or the PNP transistor and any lower readings of that voltage the transistor is faulty, refer to picture below. Also what helps is with transistors its similar to a diode but its 2 cathodes with a shared anode or 2 anodes with a shared cathode.

Experiment #4

this shows that the more voltage put in the circuit the diode and zener remain at about the same amount of voltage but the voltage drop over the resistor is alot higher at 15v than 10v to compensate. Also the amperage increases because of the higher voltage.

Experiment #3

Components: 2x Resistors, 1x 5v1 400mW Zener Diode

Resistor Values: R= 100R and RL= 100R

Voltage Supply: 12V

I vaired voltage between 12V and 15V

Value of Vz at 12V = 4.9V

Value of Vz at 15V = 5.9V

this shows that higher the voltage the higher the voltage drop across the diode but by only a small amount. I then made a smaller circuit with 1 resistor = 1K and switched between a L.E.D and a 1N4007 rectifier diode shown in this circuit below and datasheet.

Calculated and Measured Amperage

Calculated = 0.0043mA (5V - .7V/1000 = 0.0043mA)

Measured = 0.004mA

this is because the amps calculation in the circuit is a estimate of the amperage and will be close to the real value.

Calculated and Measured Voltage drop across diode

Calculated = .7V (general specifications)

Measured = .654V

this is because .7 is its max voltage drop it has.

Then added a L.E.D instead of the rectifier diode

Calculated Current = 0.0032mA (5v - 1.8v/1000 = 0.0032ma)
Measured Current = 0.0038mA

Experiment #5 Capacitors

Capacitors

There are 4 common types of capacitors

• Non -Electrolytic Capacitor



• Variable Capacitor



• Electrolytic Capacitor



• Tantalum Capacitor

A capacitor is made of 2 metal plates close together spilt by a insulator. When a capacitor is put in a circuit with a voltage supply the capacitor lets the electrons flow into the negative plate to charge and when the battery is removed it holds the charge. The time of how long it takes to charge and disapate the voltage depends on the datasheet below called a EIA code. Capacitance is also measured in Farads (F)

Circuit Capacitor Charging Circuit

Components : 1x Resistor, 1x Capacitor, 1x Switch

Calculated charge time = 100uf with 1k resistor = (0.01 x 1000 = 10 mS)

Calculated = 100uf with 0.1R resistor ( 0.01 x 100 = 1 mS)

Calculated = 100uf with 0.47R resistor ( 0.01 x 470 = 4.7mS)
Calculated = 330uf with 1k resistor (0.033 x 1000 = 33 mS)

I then measured the real charge time with oscilloscope these were results...

One Square upward is 1V and along the bottom is 1 Square per Millisecond.

The resistor affects how long it takes for the capacitor to charge and the capacitance affects how much voltage that capacitor can handle.

Diodes - Rectifier, Zener and L.E.D

Diodes

Rectifier Diode

A rectifier diode is used to change alternating current into direct current. There are many differnent kinds of rectifier diodes which all work the same way it will let voltage flow freely one way but only a small or will not flow the other way. This is how you would find the anode and cathode on it, anode being more positive than the cathode. Most rectifier diodes have a voltage drop of about .7V across it anything more or less than that it is broken. The sign when writing a rectifier diode looks like this....

Zener Diode

A Zener Diode blocks a certain amount of voltage to go through a parallel circuit and lets the rest flow through that junction, for example a 5V1 zener diode put in a 12v circuit would put 5.1 volts through the parallel circuit and let 6.9v flow through it. This all depends on what that diodes specs are on the data sheet. These diodes are similar to rectifier diodes as it the same anode and cathode set up. These diodes can be commonly used in a voltage regulator, also if you reverse the polarity of the zener diode it forces the voltage through the parallel circuit and doesnt function. The symbol used for the zener diode is..

L.E.D (Light Emitting Diode)

L.E.Ds are the most different looking of the diodes it lights up when put in a circuit. A L.E.D will usually have a 1.8v to 2.2v drop across them when you test in diode test mode on your multimeter, it also can be found on the data sheet. A L.E.D is the easiest to tell which probes are the anode and which is the cathode as the anode is longer and also flat. When the L.E.D is put in reverse bias it will not run as it becomes a insulator. The sign for L.E.D is...

Resistors in Series and Parallel circuits

Resistor In Parallel And Series.


When a resistor is put in parallel into a circuit it works differently to when its put in series. When it is in series all the resistances can be added together to give a total resistance but with parallel circuits it is the number that can be divided equally into each resistance divided by the largest resistance in the ciruit which will give you reisistance. The two formulas are set out like this






Series






Parallel

Resistors

Resistors

Resistors are colour coded to tell you the amounts of ohms each resistor can handle in the circuit for example red,red, black, yellow is 22ohms. The black line is the multiplier of the first 2 bands eg. red,red x black =22 or 22 x 1 = 22 ohms. The yellow band is the torelance which the resistor goes up to which means it should be within 5% of that coding. To check this you can use a multimeter to check if its the right size and within its tolerance.

resistor and diode in series circuit

I tested voltage drop across diode as well as resistance in the resistor. i also removed red clip and put multimeter in series with the circuit to give me current 

Completo