Objective:
The objective of this activity was to see how flip flops can be used and to get more familar with them. We created a couple of different circuits to do this.
Event Detection Circuit
Circuit Design:The first circuit we built was a photosensitive event detector. A buzzer will sound if a beam of light is disrupted. This could be used in a case such as a burgular alarm.
How does it work?In the circuit to the right, the phototransistor and the incadesecent bulb are a pushbutton switch. This is because multi-sim can't "break a light beam". When the phototransistor reads a logic 1, it will hold the CLK imput of the fip flop at a logic zero and the buzzer will not sound. When the button for the transistor reads a logic 0, the Clk input will switch to logic high and then when Que checks with D on the next pulse, it will change its output to one and the buzzer will sound. The buzzer won't go off until the reset button is pushed.
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(Click to englarge)
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Shift Register
How does it work?
Four JK flip flops are used to create a shift register. Each flip flop is connected to the same clock so they all pulse at the same time. For each pulse the output is shifted over one. The Probes are connected to the output to show the sequence. To the right of the JK flip flops is 3 NAND gates, which are used to only allow the LED (X1) to light up when the logic is 1, 0, 1 1.