Elenco Understanding Logic Gates and Circuits User Manual download pdf (Page 19)

U19

Project 12: J-K Latch

This circuit demonstrates how a J-K Latch works. Turn

the slide switch (S1) on. Connect the loose ends of

the red and black jumper wires to either 0 or 1.

 When the red jumper is connected to 0 & the black

jumper is connected to 1, then the red LED will be

off (J=0, K=1 resets the output to 0)

 When the red jumper is connected to 1 & the black

jumper is connected to 0, then red LED will be on

(J=1, K=0 sets the output to 1)

 When the red & black jumpers are both connected

to 0, then the red LED will stay the same

• Try starting with the LED off (J=0, K=1) and then move the

black lead to 0 (K=0) to see that the red LED stays off

• Try starting with the LED on (J=1, K=0) and then move the

red lead to 0 (J=0) to see that the red LED stays on

 When the red & black jumpers are both connected

to 1, then the red LED will toggle between on & off

continuously (J=1, K=1 toggles output)

• Note that the red and green LEDs appear dim when J=K=1

since they are toggling between on and off

 The green LED should always be the opposite of the

red LED (green LED off when red LED on and green

LED on when red LED off) since the green LED

represents Q which is the opposite of Q.

Details of the J-K Latch Block Diagram and Logic Chart on Next Page.

U16

U19

U16

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Elenco Understanding Logic Gates and Circuits User Manual Page 19