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I went through many types of counter in my digital electronics text book. Each one was interesting. When I came across Johnson counter, I was not able to figure out any practical application. Can anyone help me for the same?

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  • \$\begingroup\$ Numeric Nixie tubes. \$\endgroup\$ – Ignacio Vazquez-Abrams Feb 22 '14 at 4:46
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    \$\begingroup\$ Why would you want to count Johnsons? \$\endgroup\$ – Olin Lathrop Jul 22 '14 at 21:47
  • \$\begingroup\$ For the same reasons you'd want to count Peters. \$\endgroup\$ – EM Fields Jul 22 '14 at 22:04
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If you attach suitably-valued resistors to the outputs of a Johnson counter, you can synthesize some very high-quality sinewaves.

Here is one example of this.

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  • \$\begingroup\$ Johnson counters have only one output hot at a time. \$\endgroup\$ – EM Fields Jul 22 '14 at 22:00
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    \$\begingroup\$ I thought a Johnson counter was a shift register whose last stage loops to the first, and which contains an odd number of inversions [typically, though not necessarily, one]. They are often used in the implementation of one-hot counters [if each register has true and complement outputs, one can get one-hot outputs from a Johnson counter using a two-input gate for each output]. \$\endgroup\$ – supercat Jul 22 '14 at 22:18
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If you are making a decimal counter and decoding it, a Johnson counter uses 5 rather than four flip-flops, but can be decoded to 10 outputs with only 2-input gates for a net saving in CMOS technology.

Below is an example from the CD4017 datasheet.

enter image description here

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You can use it to make a sign that has a ring of lights that move in a never-ending circle around it.

I had a project where I used it to cheat in the old 80's arcade game, Track n' Field, by OR-gating two adjacent groups of three outputs (spaced by two others, totaling the 10 total outputs). Tie one group to the right button and the other group to the left button and this simulates the pushing of the left and right buttons alternatingly (with a very brief, but necessary, space in-between) to make the characters run extra fast. Imagine the hours of joy you'll have as you sit at your home arcade, alone, going round after round of defeating the computer again and again.

Sure beats being married.

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A Johnson counter can be used to divide a clock by \$2n\$. So in contrast to chain of T-FF - which generate a by \$2^n\$ divided clock - a Johnson counter can divide by every even number. If you change the counters init value, it's also possible to configue other duty cycles then 50:50.

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