Martin:

Using AC (triac method )to control the nitinol wires is possible. But I strongly
suggest that you use zero crossing opto isolators to do the switching. Check
out Digi Key for a selection of solid state relays. Everything you need for AC
switching in one package. A lot of the relays are TTL compatible.

The other scheme that you were refering to in your second post was using SCR,s
in a bridge configuration. This scheme is even more diffcult to emplement than
PWM.

You could try the SGS Thompson L298n this is a TTL compatible Dual H-Bridge
capable of 1.5 amps per bridge. Standard chip used to drive Electro Magnets
Steppers etc.. I believe that Texas Instr. makes this chip also.

>        1)  Would someone suggest an efficient way to switch A/C power using
>PIC outputs.
>
>        2)  I have been looking into using a triac but I have little
>experience with them and I am not sure just how they work.  Does a triac
>switch on and off with it's control or does it stay triggered as long as
>the A/C power is applied?
>
>Thanks all,

>>A quick follow on question,
>>
>>        I seem to remember a device which allow one to apply some
>>percentage of the AC waveform similar to pulse width modulation.  That
>>is:
>>        full power = full waveform
>>        half power = 180 degrees of waveform
>>        X% power   = appropriate % of the waveform
>>
>>I do not remember what that device is.  Any help?
Joseph D. West
Electronics Lab. Supervisor
College of Mechanical Eng.
Ohio State University

(614) 292-2845
Fax (614) 292-3163