Download The Clock Pulse Generator

The Clock Pulse Generator
Standard Grade Physics : Mearns Academy
The Clock Pulse Generator
+6V
R2
Y
R1
C
X
A
0V
This is the basic circuit diagram for the clock pulse generator.
The Clock Pulse Generator
High = 1= +6V
Low = 0 = 0V
The Clock Pulse Generator-in stages
Y
R1
C
X
A
0V
At the start the capacitor is uncharged so the voltage
at X is 0V.
The NOT gate inverts the signal, so the voltage at A is 6V.
The voltage at Y is also 6V.
The Clock Pulse Generator-in stages
6V
R1
C
0V
6V
0V
At the start the capacitor is uncharged so the voltage
at X is 0V.
The NOT gate inverts the signal, so the voltage at A is 6V.
The voltage at Y is also 6V.
The Clock Pulse Generator-in stages
6V
High voltage
R1
C
0V
0V
Output is high.
6V
The Clock Pulse Generator-in stages
Y = 6V
R1
C
X = 0V
A = 6V
0V
The capacitor starts to charge up through the resistor R1
The Clock Pulse Generator-in stages
Y = 6V
R1
C
X = 0V
A = 6V
0V
The capacitor starts to charge up through the resistor R1
The voltage at X will now become 6V
The voltage at A will now become 0V
The voltage at B will now become 0V
The Clock Pulse Generator-in stages
Y = 0V
R1
C
X = 6V
A = 0V
0V
The capacitor starts to charge up through the resistor R1
The voltage at X will now become 6V
The voltage at A will now become 0V
The voltage at B will now become 0V
The Clock Pulse Generator-in stages
Y = 0V
High
voltage
R1
C
X = 6V
0V
Output is low
A = 0V
Low
voltage
The Clock Pulse Generator-in stages
Y = 0V
R1
C
X = 6V
A = 0V
0V
Since the voltage at X is now 6V and at Y it is now 0V, the
capacitor will start to discharge through resistor R1
The Clock Pulse Generator-in stages
Y = 6V
R1
C
X = 0V
A = 6V
0V
Since the voltage at X is now 6V and at Y it is now 0V, the
capacitor will start to discharge through resistor R1
The voltage at X will now become 0V
The voltage at A will now become 6V
The voltage at B will now become 6V
The Clock Pulse Generator-in stages
Y = 6V
High
R1
C
X = 0V
A = 6V
0V
…and the cycle repeats itself.
High
Low
The Clock Pulse Generator-seeing the
pulses
+6V
+6V
Y=6V
R1
C
X=0V
A=6V
0V
When the capacitor is uncharged, the output of the NOT gate is high.
There is no voltage difference across the LED so it does not light
The Clock Pulse Generator-seeing the
pulses
+6V
+6V
Y=0V
R1
C
X=6V
A=0V
0V
When the capacitor is charged, the output of the NOT gate is low.
The voltage difference across the LED is 6V so it lights.
The Clock Pulse Generator
Output High
(LED Off)
Large R and C
Low Frequency
Output Low
(LED On)
Small R and C
High Frequency
The Clock Pulse Generator-the LED bit
+6V
+6V
Y=0V
R2
R1
C
X=6V
A=0V
0V
The maximum voltage across the LED part of the circuit is 6V
Why is there a series resistor R2 in this part of the circuit?
The Clock Pulse Generator-the LED bit
+6V
+6V
Y=0V
R2
R1
C
X=6V
A=0V
0V
The maximum voltage across the LED part of the circuit is 6V
The LED is protected by the resistor R2 because it will be
damaged if it has more than 2V or 10mA.
The Clock Pulse Generator-the LED bit
+6V
+6V
Y=0V
R2
R1
C
X=6V
A=0V
0V
Calculate the value of series resistor R2
Voltage across R2 = 4V, I = 0.01A, R = V/I = 4/0.01 =400Ω
The Clock Pulse Generator-the LED bit
+6V
+6V
Y=0V
R2 =400Ω
R1
C
X=6V
A=0V
0V
Calculate the value of series resistor R2
Voltage across R2 = 4V, I = 0.01A, R = V/I = 4/0.01 =400Ω
The Binary Counter
The Binary Counter
The Decoder and 7- Segment Display
The Decoder and 7- Segment
Display
7-segment Display
Page 23 in Notebook: The 7-segment display is named
because it is made up of 7 separate LEDs, which light
depending on which decimal number is required.
Complete note on Page 23.
7-segment Display
Zero …..a,b,c,d,e,f…..
7-segment Display
Zero …..a,b,c,d,e,f…..
7-segment Display
One ….. b,c…..
7-segment Display
Two …..a,b,d,e,g…..
7-segment Display
Three …..a,b,c,d,g…..
7-segment Display
Four ….. b,c,f,g…..
7-segment Display
Five ….. a,c,d,f,g…..
7-segment Display
Six ….. a,c,d,e,f,g…..
7-segment Display
Seven ….. a,b,c, …..
7-segment Display
Eight ….. a,b,c,d,e,f,g …..
7-segment Display
Nine ….. a,b,c,d,f,g …..
7 Segment Display
Which number?
2
Putting it all together
Clock Pulse
Generator
Binary
Counter
7-segment
Display
Putting it all together
Clock Pulse
Generator
Digital output
Binary
Counter
7-segment
Display
Putting it all together
Clock Pulse
Generator
Binary
Counter
000101
Digital output
Binary output
7-segment
Display
Putting it all together
Clock Pulse
Generator
Digital output
Binary
Counter
7-segment
Display
000101
5
Binary output
Decimal output