I have a problem with stabilize the output current of a DAC, cause i'm in a task of making a electric physiotherapy device (the same type as TENS but i'm not making square wave, instead i'm trying triangle and sine wave). I have successfully generate wave by using two module MCP4725 and
GY AD9833(arduino code involve), now my instructor said that my current should be at one level only(5mA at most). But i'm thinking that because when generate a electric wave, the voltage will constanly changing in an order that shape the wave i want, but based on Ohm law: U=IR. How can I stay while U changes, any recommendations? Thank you very much for having attention in this post.

 

How can I stay while U changes

It can't.

 

now my instructor said that my current should be at one level only(5mA at most)

The instructor may be referring to the RMS or peak current level, rather than the instantaneous level. There is also a distinction between stabilising a current and limiting a current. Get clarification from the instructor.
Welcome to AAC!

 

This is good question for your instructor, since what you describe sounds impossible, we probably misunderstand the requirement (As Alec_t) indicated.

 

You can design a circuit to limit the current to 5mA, or provide a constant-current of 5mA independent of the resistance.
Which of those do you want?

 

Usually, but not always, the stated current would be at the maximum voltage. To get the best answer, show a drawing of the waveform asking at what point on the voltage wave should the current be the specified 5 ma. THAT is how to have an adequate specification.

Of course, if the voltage source is adjustable then adding a variable series resistor will allow adjusting the current as the load resistance varies.