The Clock Pulse Generator Standard Grade Physics : Mearns Academy The Clock Pulse Generator R1R1 C +6V 0V Y X A R2R2 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 R1R1 C 0V Y X A 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 R1R1 C 0V 6V 0V 6V 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 R1R1 C 0V 6V 0V 6V Output is high. High voltage The Clock Pulse Generator-in stages R1R1 C 0V Y = 6V X = 0V A = 6V The capacitor starts to charge up through the resistor R 1 The Clock Pulse Generator-in stages R1R1 C 0V Y = 6V X = 0V A = 6V The capacitor starts to charge up through the resistor R 1 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 R1R1 C 0V Y = 0V X = 6V A = 0V The capacitor starts to charge up through the resistor R 1 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 R1R1 C 0V Y = 0V X = 6V A = 0V Output is low High voltage Low voltage The Clock Pulse Generator-in stages R1R1 C 0V Y = 0V X = 6V A = 0V Since the voltage at X is now 6V and at Y it is now 0V, the capacitor will start to discharge through resistor R 1 The Clock Pulse Generator-in stages R1R1 C 0V Y = 6V X = 0V A = 6V Since the voltage at X is now 6V and at Y it is now 0V, the capacitor will start to discharge through resistor R 1 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 R1R1 C 0V Y = 6V X = 0V A = 6V and the cycle repeats itself. High Low High R1R1 C +6V 0V Y=6V X=0V A=6V The Clock Pulse Generator-seeing the pulses +6V 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 R1R1 C +6V 0V Y=0V X=6V A=0V The Clock Pulse Generator-seeing the pulses +6V 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) Output Low (LED On) Large R and C Low Frequency Small R and C High Frequency R1R1 C +6V 0V Y=0V X=6V A=0V The Clock Pulse Generator-the LED bit +6V The maximum voltage across the LED part of the circuit is 6V Why is there a series resistor R 2 in this part of the circuit? R2R2 R1R1 C +6V 0V Y=0V X=6V A=0V The Clock Pulse Generator-the LED bit +6V The maximum voltage across the LED part of the circuit is 6V The LED is protected by the resistor R 2 because it will be damaged if it has more than 2V or 10mA. R2R2 R1R1 C +6V 0V Y=0V X=6V A=0V The Clock Pulse Generator-the LED bit +6V Calculate the value of series resistor R 2 Voltage across R 2 = 4V, I = 0.01A, R = V/I = 4/0.01 =400 R2R2 R1R1 C +6V 0V Y=0V X=6V A=0V The Clock Pulse Generator-the LED bit +6V Calculate the value of series resistor R 2 Voltage across R 2 = 4V, I = 0.01A, R = V/I = 4/0.01 =400 R 2 =400 The Binary Counter 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 Binary Counter 7-segment Display Digital output Putting it all together Clock Pulse Generator Binary Counter 7-segment Display Digital outputBinary output Putting it all together Clock Pulse Generator Binary Counter 7-segment Display Digital output Binary output 5 Decimal output