Please see this for experiment details: http://ap.smu.ca/demos/index.php?option=com_content&view=article&id=224&Itemid=205 [Broken] It is the classic: create a standing wave with a certain number of nodes. I can find a function generate that can output the desired frequency to produce these on a string. My trouble is when I want to add a strobe effect to match the frequency of the wave to create an illusion that the wave is standing still. My problem is I can't find a strobe light with the desired frequency control. Most I found have a 10-20Hz output. I am looking for one in the range of 20-100Hz. Do know how I can get one of these? Or make one? thanks!