Democracy for rotary

Analog Circuit for Rotary Encoder

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My project is an analog electronic circuit designed to build a rotary encoder system without using a digital technology, it's verry simple and cheaper and simplifies every project need a rotary encoder, enjoy .

The priciple of this circuit is a rotary encoder switch with a special flip flop design using 6 transistors , the first led lit blocks the second one, and transistor T7 have the role of timing the lighting of the LED's and reseting the circuit when the rotary encoder does not pass voltage.

the optocouplers have the role to protect the circuit and it's more stable .

NOTE: Exuse my English

- Firstly the Rotary encoder is an electromechanical device that is used to encode a digital signal applied to a microcontroller to define what direction turns and count the number of pulses to manage any system using this principle as the volume control or the frequency control my system uses the analog properties of the rotary encoder to do the same thing, watch this video to understand with this simple installation.

There are 4 steps:
- first step: If you slowly turn from the right direction, the right LED switch on first
- second step: the left LED switch On after.
- third step: the right LED switch off.
- fourth step: the left LED switch off after.

- Then The rotary encoder back to the beginning of its sycle in this position both LEDs are off.

- And if you start from the left, the same steps occur in the opposite direction.

- Then, if you connect the rotary encoder to my flip-flop circuit using six transistors it will block the second LED to turn on, then at each sycle it is always the first LED that will light.

- Now we know which direction turns the rotaty encoder, we have just to put the circuit to its initial state at every sycle, we will do this with the transistor number 7 who have two functions reseting the system and timing the lignting of the LED's every sycle.

- Finaly there are many advantages of this circuit design, its easy to build- cheaper-compact- simple- and does not consume energy in standby state.

  • 1 × capacitor 100 n
  • 7 × R1-R3-R4-R6-R8-R9-R12 = 10k
  • 6 × R2-R5-R7-R10-R13-R14 =100K
  • 5 × T1-T3-T4-T6-T7 = BC238
  • 3 × T2-T5 =BC308

View all 10 components

  • Note:

    Adnane Belarif04/24/2015 at 13:12 0 comments


    sometimes some blink does not appears, you have to review the video to see them, i dont know why, this is a youtube problem,

  • The Assembled circuit

    Adnane Belarif04/23/2015 at 21:41 0 comments

    Hi everyone, this is my assembled circuit board , it works very well.

    This is the video :

    Thank you to follow my project, and be happy with simple things :)

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Adnane Belarif wrote 04/13/2015 at 17:01 point

Thank you for the skull , yes you undestoon the circuit very well , this a special design flip-flop circuit associate to Transistor T7 used to generate a pulse every sycle, and by this way reseting the system.

goodluck for you projects , i am following you .

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Eric Hertz wrote 04/13/2015 at 00:23 point

Excellent! The new schematic is easy to follow. I think I even understand it, despite my not being too fluent with transistor-circuits. :) 

(Are all the transistors used in either Off or Saturation?)

The video that's linked is great. I dig the one-shot aspect (transistor 7, with the capacitor), just giving a pulse when the knob is moved, rather than staying on.

I can't quite wrap my head around what happens in some odd-cases, like what if it's powered-up when *both* the encoder-channels are On. But, that's a cool thing about the one-shot... it doesn't really matter what happens in odd-cases like that, because it will reset itself until the next motion. Cool.

Thanks for posting this, my friend! I'm getting all sorts of ideas how to use this...

Use an old (ball) mouse (or some optical mice even have quadrature outputs on their driver-chips)... connecting it to a gaming-controller's D-pad, feeding it into a stepper-motor driver's Step/Direction inputs with just a tiny bit more logic... Cool.

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