What is a binary counter?

A sequential logic circuit that counts in standard binary sequence, with each flip-flop representing one bit of the count value.

What is a BCD counter?

A Binary Coded Decimal counter that counts from 0000 to 1001 (0 to 9 in decimal) then resets to 0000, representing each decimal digit in four bits.

What range of values does a BCD counter cycle through before resetting?

0000 to 1001 (0 to 9 in decimal).

What is a Johnson counter?

A twisted ring counter consisting of a shift register where the inverted output of the last flip-flop is fed back to the input of the first.

In a Johnson counter, what is fed back to the input of the first flip-flop?

The inverted output of the last flip-flop.

AQA A-Level Physics 7408

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Topic overview MOSFET (metal-oxide semiconducting field-effect transistor)Zener diode Photodiode Hall effect sensor Difference between analogue and digital signals LC resonance filters The ideal operational amplifier Inverting amplifier configuration Non-inverting amplifier configuration Summing amplifier configuration Real operational amplifiers Combinational logic Sequential logic Astables Principles of communication systems Transmission media Time-division multiplexing Amplitude (AM) and frequency modulation (FM) techniques

Electronics

Sequential logic

4 things to know
Paper 3, section B

Overview

Flip-flops, the clock, binary and Johnson counters, and the reset and up/down inputs.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Process

What does the clock input do, and what is fed back in a Johnson counter?

Key term

What do the reset and up/down inputs do, and what do the outputs represent?

Numbers

How many states does a 4-bit counter cycle through, and how many does a Johnson counter give?

Numbers

How many of the possible 4-bit states does a BCD counter use?

Questions from this subtopic

Each one with the model answer underneath.

1
What is a binary counter?
Model answer
A sequential logic circuit that counts in standard binary sequence, with each flip-flop representing one bit of the count value.
2
In a binary counter, what does each flip-flop represent?
Model answer
One bit of the count value.
3
What is a BCD counter?
Model answer
A Binary Coded Decimal counter that counts from 0000 to 1001 (0 to 9 in decimal) then resets to 0000, representing each decimal digit in four bits.
4
What range of values does a BCD counter cycle through before resetting?
Model answer
0000 to 1001 (0 to 9 in decimal).
5
What is a Johnson counter?
Model answer
A twisted ring counter consisting of a shift register where the inverted output of the last flip-flop is fed back to the input of the first.
6
In a Johnson counter, what is fed back to the input of the first flip-flop?
Model answer
The inverted output of the last flip-flop.

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