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I have a 0-3.3V output that I wish to amplify to 0-10V.

I am using an 8-bit R2R resistor ladder connected to a National Instruments USB-6501 digital I/O device.

The application is to control a linear actuator via a controller that requires a 0-10V command signal therefore I need to amplify the output from the resistor ladder.

Would be grateful for any advice on how this can be achieved, thank you.

Newbie
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1 Answers1

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One approach is to use a non-inverting amplifier at the end of the DAC output, supplied by atleast 10 volts.

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The DAC output in this case will be \$V_{in}\$

\$ V_o = V_{in}( 1 + R_1/R_2)\$

Lets say we want \$V_o = 10V\$ , when \$V_{in}= 3.3V\$

\$10 = 3.3(1+R_1/R_2)\$

\$10/3.3-1 = 2.0303 = R_1/R_2\$

So one way to go at it , is make a non-inverting amplifier with a gain of roughly 2, by using 2Kohm for feedback resistor \$R_1\$ and 1Kohm for the other resistor \$R_2\$

8-bit resolution means the range is 255 discrete voltages. So 10V/255 bits = \$ 39.2mV\$/ bit

Iancovici
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  • That'd be 39.2mV per bit – Andy aka Aug 07 '13 at 11:37
  • Thanks for the advice echad and Andy aka, could you recommend an op-amp IC, from googling this type of solution, the 741 is both recommended and dismissed (not able to operate at 0-3.3V) so not sure which to go with, thanks. Newbie – Newbie Aug 07 '13 at 11:45
  • It really depends on the application, how accurate you want it to be. You'll probably want to look for P/DIP package types (prototyping friendly). You can find them at places like [digikey](http://www.digikey.com/product-search/en/integrated-circuits-ics/linear-amplifiers-instrumentation-op-amps-buffer-amps/2556125?k=op%20amp), mouser, newark or smaller stores like [Sparkfun](https://www.sparkfun.com/products/9456) – Iancovici Aug 07 '13 at 11:50