# DC Voltage scalar?

#### 00600

##### Member
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

##### Member
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!