Thursday, July 29, 2010
Experiment no.5 ( capacitor )
Experiment no.4 ( 5,1 zener diode )
Wednesday, July 28, 2010
Experiment no.3 ( 5.1 zener diode )
Components : 2x resistors,1x 5.1 400mW zener diode (Zd)
Vz = zener voltage
Vs = voltage supply
The value of Vz : 5volts
Vs now varys from 10 -15 v
What is Vz now: 5volts
NOTE:
Component voltage dos'nt change as this voltage amount is to operate the component, Zener diode has a reverse bias of 5.1 v and a forward bias 0.7v
Changing the supply voltage wont change a diodes voltage, only changing the diodes forward or reverse bias wil change its voltage drop.
Zener diodes are good for circuits containing different voltage components.
Reversing the polarity of the zener diode:
0.846 was measured in this reversed polarity giving a forward bias, which should read between 0.6-0.7, the reading 0.8 would mean there was a leak in the diode exceding its forward bias voltage.
Vz = zener voltage
Vs = voltage supply
The value of Vz : 5volts
Vs now varys from 10 -15 v
What is Vz now: 5volts
NOTE:
Component voltage dos'nt change as this voltage amount is to operate the component, Zener diode has a reverse bias of 5.1 v and a forward bias 0.7v
Changing the supply voltage wont change a diodes voltage, only changing the diodes forward or reverse bias wil change its voltage drop.
Zener diodes are good for circuits containing different voltage components.
Reversing the polarity of the zener diode:
0.846 was measured in this reversed polarity giving a forward bias, which should read between 0.6-0.7, the reading 0.8 would mean there was a leak in the diode exceding its forward bias voltage.
Wednesday, July 21, 2010
experiment no.2 ( diodes )
Diodes are symbolised by a white ring on the diode, closet to the cathode end indicating the negative end of the diode.
When the cathode end of the diode is connected to the earth of the power supply the diode is in forward bias
Reverse bias is when the diode is conected back to front
Reverse bias is when the diode is conected back to front
calculate the value of current flowing through the diode:
calculated : i=v/r = 5.02-0.7/1000 = 0.00432 = 4.32 ma
measured : 4.35 ma
To find the amount of current flowing through the diode, i
used the formula i = v/r , dividing the voltage by the resistance giving me the current .
calculate the voltage drop across the diode :
calculated : v= i x r =
measured : 0.65 v
maxium value of current flow through the diode:
maxium value of supply voltage (Vs) at which the diode is safe to run:
v=ixr= 1x1000 = 1000@75degreesceluis
Diode is replaced by LED :
calculated: 5.02 -1.8/1000 = 3.22/1000 = 0.00322 ma
measured: 3.3 ma
NOTE: LED circuit uses more volts but less amperage than the diode.
Experiment no.1 (resistors)
NOTE:
In a series circuit resistance is added together to giving a prpportional decrease in the flow of current ,in addtion a lower resistance reading.
resistance in a parallel circuit
-
Working:
Resistor 1 : 98900 ohms
Resistor 2 : 389 ohms
Both in series :
calculated : 99289 ohms
measured : 99200 ohms
Both in parallel :
calculated : 387.48 ohms
measured : 388 ohms
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