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I am planning to make a digital control board which can draw a DC Voltage of the order of say 12-15 Volt, from a single source and give multiple number ( approximate #100 ) of voltage lines of different values range from 0.1 to say 6/7 Volt with a fine resolution ( it is possible to differentiate between two output lines on the order of say mV). Voltages appeared to output lines should be controlled electronically.

So how to design this board ? What type of programming needs ?

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  • \$\begingroup\$ So you're asking how to design a board with a hundred of different, mV precise, digitally controlled voltages, right? What currents are we speaking of, and what budget. \$\endgroup\$ Nov 17 '15 at 20:27
  • \$\begingroup\$ Hi, thanks for reply and right what you are interpreting. Current is in order of nA and power is in order of few hundred mW. \$\endgroup\$
    – aran
    Nov 17 '15 at 20:38
  • \$\begingroup\$ Just buy 100 DACs. You need some 13 bits, 14 is better. Depending on required bandwidth price ranges from a few dollars each up to several tenths. And you will need a microcontroller with spi and a hundred gpios. Pretty pricey, and I can't really imagine what that's for. \$\endgroup\$ Nov 17 '15 at 20:43
  • \$\begingroup\$ What calibration procedure have you considered might be needed for this circuit? What accuracy? What resolution? What noise levels on outputs are acceptable and precisely what is the load impedances in ALL its manifestations? Do outputs require isolation or are they all 0V referenced? SPI control? Another control? Temperature variations the design will be subject to? \$\endgroup\$
    – Andy aka
    Nov 17 '15 at 21:05
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    \$\begingroup\$ The smart way to do this is to visit a DAC manufacturer site (Maxim, Analog Devices, Texas (the usual suspects)) and look for multi-channel DACs using their parameteric search pages. For instance the MAX5733 is a 32 channel, 16 bit per channel, 0 to 10v output, serial programmable device. It's many 10s of $, but you'd only need 3, and save yourself a mega rat's nest of building. I don't know how you could do it more easily or cheaply than that, unless you have some other specifications you've not shared. \$\endgroup\$
    – Neil_UK
    Nov 17 '15 at 21:33
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You can try to use a microcontroller with PWM output. Filter the PWM with high RC. Use an op-amp to buffer the output and give a gain of say 10x.

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