DC Voltage scalar?

00600 · 31st December 2007, 09:59 PM

I have a controller that takes a fluctuating DC Voltage input (.4v-1.0v) and scales it according to several factors (some user definable), and then outputs it.

The problem I have is, I need to be able to scale 4 inputs the same amount, but the voltages need to be independent. I also need to be able to clamp the output at a min/max of .4v/1.0v

IE:

Input_______controller_______Output

1=.4v_______+.2v____________1=.6v
2=.65v_____________________2=.85v
3=1.0v_____________________3=1.0v
4=.9v______________________4=1.0v

Input_______controller_______Output

1=.4v_______-.2v___________1=.4v
2=.65v____________________2=.45v
3=1.0v____________________3=.8v
4=.9v_____________________4=.7v

I need to be able to process these signals in under 10ms with a resolution of 0.01v

The main reason I don't just buy another controller, is because this scaling function is just one of many processes the unit controls, and each unit costs $1,000.00
any ideas?

cliffforrest · 31st December 2007, 10:37 PM

With that resolution an 8bit engine will get you to +/- 2.56V, or +/- 1.28V with 5mV resolution.

If the transfer function is as simple as you state, then a 256 step look-up table will be bomb proof.

Use one of the many PIC single chip engines for very easy developement - built in DACs

Happy New Year, BTW!

31st December 2007, 09:59 PM	#1
00600 diyAudio Member Join Date: Aug 2007	DC Voltage scalar? I have a controller that takes a fluctuating DC Voltage input (.4v-1.0v) and scales it according to several factors (some user definable), and then outputs it. The problem I have is, I need to be able to scale 4 inputs the same amount, but the voltages need to be independent. I also need to be able to clamp the output at a min/max of .4v/1.0v IE: Input_______controller_______Output 1=.4v_______+.2v____________1=.6v 2=.65v_____________________2=.85v 3=1.0v_____________________3=1.0v 4=.9v______________________4=1.0v Input_______controller_______Output 1=.4v_______-.2v___________1=.4v 2=.65v____________________2=.45v 3=1.0v____________________3=.8v 4=.9v_____________________4=.7v I need to be able to process these signals in under 10ms with a resolution of 0.01v The main reason I don't just buy another controller, is because this scaling function is just one of many processes the unit controls, and each unit costs $1,000.00 any ideas?

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31st December 2007, 10:37 PM	#2
cliffforrest diyAudio Member Join Date: Sep 2004 Location: UK	With that resolution an 8bit engine will get you to +/- 2.56V, or +/- 1.28V with 5mV resolution. If the transfer function is as simple as you state, then a 256 step look-up table will be bomb proof. Use one of the many PIC single chip engines for very easy developement - built in DACs Happy New Year, BTW!