Reference no: EM131018760

Lab- J-K FF

Objectives

The following are objectives of this lab:

Use various conditions to test the characteristics of the J-K flip-flop. Included in the procedures are various asynchronous and synchronous input modes.

Materials Needed

1. 74LS76 dual J-K flip-flop

2. LEDs: (1) red, (1) green, (1) yellow

3.   Resistors:  (3) 330?, (4) 1.0 k?

4. One 4-position DIP switch

5. Function Generator / Oscilloscope / Leads / KeySight BenchVue software

Background

The J-K flip-flop is a clocked S-R flip-flop with additional circuitry to replace the invalid state of S = 1, R = 1. The new mode when J = 1 and K = 1 is called toggle. The toggle state causes the flip- flop to change state to the opposite state if both S and R equal 1. Tables 1 a, b, and c below give the states for each type of flip flop for all states of input.

S-R FF

Inputs S         R		Output Q
0	0	Latched
0	1	0
1	0	1
1	1	Invalid

Table 1a

D-Latch

Input D	Output Q
No equivalent
0	0
1	1
No equivalent

Table 1b

J-K FF

Inputs J          K		Output Q
0	0	Latched
0	1	0
1	0	1
1	1	Toggle

Table 7-1c

The J-K FF will be used in this lab to demonstrate its unique capabilities.

Procedure

1. Turn on computer and locate KeySight BenchVue software.

Turn on the Oscilloscope (reads outputs) / Function Generator (clock input). (You may need T.A. or instructor assistance)

Construct the circuit of Figure 1 below.

Set (PRE)‾ and (CLR)‾ to a logic 1.

Connect the TTL signal from the function generator and set frequency to 1 Hz.

Using the BenchVue software, save a screenshot of the input (Channel 1) and output, Q, (Channel 2) for all combinations of J and K. Label all screenshots appropriately.

2. Construct the circuit of Figure 2.

Using the BenchVue software save screenshots of the input (Channel 1) and output, Q‾, (Channel 2) for all combinations of J and K. Label all screenshots appropriately.

3. Construct the circuit of Figure 3.

Using the BenchVue software save screenshots of the outputs, Q₁and Q₂ on the same screen (Channels 1 and 2) for all combinations of J and K. Then repeat this for outputs, Q₁‾ and Q₂‾ for all combinations of J and K.  Label all screenshots appropriately.

HD74LS76A

REQUIRED SUBMITTAL: You will NOT turn in this handout!!!

You will do a formal lab report including the following sections:

OBJECTIVE (Sentence format. Be thorough!)

DATA -Use Multisim to create the circuits constructed in Figure 1, 72 and 3. Give each circuit a meaningful name that explains their function. Include labeled screenshots taken in the course of the lab (these should have labels similar to the circuit labels).

DISCUSSION - (Sentence / Paragraph format) Discuss the operation and/or function performed by each of the (3) flip-flop circuits by analysis of the outputs.