Hi all,

I'm looking for help on how to regulate current through a varying load. The load mentioned is a shape memory alloy wire which contracts when heated via current being passed through it. Upon contraction the resistance of the wire changes due to a phase change in the material. For my first test I need to maintain a constant current of 400mA through the wire before, during and after contraction. Following this, I need to repeat the test at 395mA, 390mA, all the way down to 220mA. Any help would be appreciated. Thanks guys

 

Depending on the source voltage, that should be well within the capability of an LM317 configured as a current regulator. Get the data sheet - http://www.national.com/ds/LM/LM117.pdf- and see what you think.

 

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