Analog Signal Generator Design

[AnalogKid]

Datel used to make a voltage calibrator packaged in a 4-1/2 digit industrial panel meter case. Don't know if they still do, but it is exactly what you describe.

ak

 

[MrAl]

Hi,

Quick note for a much earlier reply:
With a 12 bit DAC you do not get a count of 0 to 4096 you get a count of 0 to 4095.

A few more notes:
With a voltage reference of 4.096v you get an output voltage of 0 to 4.095 volts, and with 12 bits that means 1mv per step. If you amplify that with a gain of 2 though it's back up to 2mv per step with a range of 0 to 8.190v.
If you instead start with a 5v reference then you get an output range of 0 to 4.998779v and a step size of about 1.2207mv approximately. If you amplify that with a gain of 2 double those numbers.
If you adjust the gain slightly higher in either case you can get 0 to 10v.

It's best to make the 7 segment display an actual volt meter so that it actually measures the output rather than assume the output is some set level based on the count setting because output loading will affect the true output voltage. That would be done with a separate ADC.

There are different kinds of Arduinos, not all are the same. The Uno for example has a 10 bit ADC and only 8 bit PWM output, but the Due for example has a 12 bit ADC and a 12 bit DAC on board however it works with only a 3.3v supply voltage although you could amplify the DAC output on the Due also. This means that there is a chance that the Due board would be able to do everything you need except amplify the output where you would need an op amp and decent supply voltage of maybe 12v to 15vdc.

 

[AnalogKid]

It's best to make the 7 segment display an actual volt meter so that it actually measures the output rather than assume the output is some set level based on the count setting because output loading will affect the true output voltage. That would be done with a separate ADC.

Completely agree. But designer beware. Now not only do you need a 12-bit-accurate voltage reference for the D/A system, you also need one for the A/D system for "full accuracy".

Actually, 12-bit accuracy is a theoretical minimum. In the real world, where a 10:1 instrument-to-DUT ratio is the rule of thumb, you would need a 15-bit or 16-bit accurate reference for true 12-bit measurement accuracy. You can use the same reference for both the D/A and A/D, but then the displayed readings are ratiometric rather than absolute.

ak

 

[Kamillas]

Hi All,

Thanks for all your help. I was able to generate 0 to 10V from the setup(Arduino Mega and MCP4725) without any issue. I have interfaced an LCD display with the Arduino to show the current voltage output (Calculated). Also I interfaced four buttons with the Arduion to increase or decrease the voltage.

I am not able to upload pictures from my mobile phone (Due to image size). I will post some pictures soon.