How to Design a Divide by 3 Sequential Circuit
The "divide-by-three" circuit is one of a class of circuits for performing frequency division. It takes an incoming electronic signal through the clock input pin, and outputs it through a different pin at one-third of the clock input frequency. Most stand-alone frequency division circuits divide by a power of two (divide-by-four, divide-by-eight, and so on). To create a divide-by-three circuit, you will need three gates: two flip-flops and the “Not OR” (NOR) logic gate. Since the 7474 flip-flop integrated circuit (IC) has two separate flip-flop circuits on board, you will only need two chips to construct this frequency division circuit.
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Things You'll Need
- One 7474 D flip-flop
- One 7402 NOR logic gate
- Five-volt square wave generator
- One breadboard
- Jumper wires
- Two resistors
- Two LED lights
Instructions
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1
Place the flip-flop and the NOR chip at the center of the breadboard side-by-side. Running down the center of the breadboard is a long groove. Align each chip so that one row of pins fits on each side of this groove.
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2
Connect the square wave generator to pin three (Clock1) on the first flip-flop. A square wave generator is a device that releases bursts of electric current at a regular interval or frequency. This frequency pulse will be divided by the divide-by-three circuit.
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3
Connect a jumper wire from pin three (Clock1) to pin 11 (Clock2) on the flip-flop chip.
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4
Connect a jumper wire from pin two on the flip-flop chip (D1) to pin two on the NOR chip (A1).
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5
Connect a jumper wire from pin five on the flip-flop (Q1) to pin three on the NOR chip (B1).
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6
Connect a jumper wire from pin two on the nor chip (A1) to pin nine on the flip-flop (Q2).
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7
Connect a jumper wire from pin one on the NOR chip (Y1) to pin twelve on the flip-flop (D2).
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8
Connect a jumper wire from pin nine on the flip-flop (Q2) to the load. The load can be a light, buzzer or another electronic device. Make sure to insert resistors, if necessary.
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9
Connect pins six (Not Q1)and eight (Not Q2) on the flip-flop to ground.
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1
Tips & Warnings
To see the label name on each pin on either a flip-flop or NOR integrated circuit, review the datasheet for each chip. See the References section for sample datasheets for standard flip-flops and NOR chips.
