Encoder TTL Signal Modification

Discussion in 'The Projects Forum' started by therealkilkenny, Apr 14, 2009.

  1. therealkilkenny

    Thread Starter New Member

    Apr 14, 2009
    2
    0
    Hi Guys and Gals,

    I've got a couple of encoders that output various types of signals and i've got some ultrasonic kit that reads in encoder signals. The problem is that they are different and i need to make something that will interface between the two. BTW i'm an electronics newbie.

    My ultrasonic hardware is looking for an A and B channel in order to count (if A is before B then clockwise and vice a versa). The problem is that my encoder only outputs an A signal and therefor i need to create a B. Normally A and B are 90 degrees out of phase with each other but i have discovered that if i delay A by 500nS then it will do as a 'B'. I found some chips on the internet that were 500nS delay lines and got these.

    The signal from my encoder is also upside down - high-low-high. I need to make this low-high-low. I found some NOT gates on the internet that would do this.

    I also want to double the frequency of my signal. I found some XOR gates on the internet and got these. I can feed the A and B into this to create A' that is double the frequency. I can then run this through a delay line to give B' and thus double the frequency of the encoder.

    The pictures below show the assembled device with a couple of screen shots of the output signals.

    [​IMG]

    [​IMG]

    [​IMG]

    Now it kind of works, but as you can see there are glitches in the signals and ringing which cause the ultrasonic hardware to count in multiples (2/4/8 etc) because the timer on the ultrasonic hardware is very sensitive.

    What i want to know is, how do i fix this? Are there any products on the market that might do all this for me? Would anyone be interested in designing this for me a bit better on a paid basis?

    Thanks,

    Phil
     
  2. therealkilkenny

    Thread Starter New Member

    Apr 14, 2009
    2
    0
    Hi,

    Thanks for the response. Unfortunately i cannot do ANYTHING about the ultrasonic hardware or the encoders, so i have to find some other way of doing it.

    Phil
     
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