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IndustryArena Forum > CNC Electronics > PIC Programing / Design > isolated DAC. PWM ( 20khz ) to analog 0-10Volt
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  1. #1
    Join Date
    Jan 2007
    Posts
    93

    isolated DAC. PWM ( 20khz ) to analog 0-10Volt

    I have found this shematics .

    For R6 and R7 i have put 33kohm resisitors and i get 2.5 Volt output when there is no signal.

    Anyone knows calculation for this circuit?
    Attached Thumbnails Attached Thumbnails IsolatedDAC.jpg  

  2. #2
    Join Date
    Feb 2007
    Posts
    962

    Re: isolated DAC. PWM ( 20khz ) to analog 0-10Volt

    What you want is when there is no input, the output is zero.
    The 1st amp is an inverting amp. so then there is no input, the - input is pulled high, making the output low.

    I would increase R4 to give the inverting buffer (1st amp) a very high gain. Make R4 1Meg and see the result.

    R6 and R7 are ok at 33k or 100k since they are just a voltage divider.

    Larry
    Manufacturer of CNC routers and Viper Servo Drives
    www.LarkenCNC.com and www.Viperservo.com

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