I need to make a pulse of varing length. Either I need a VCR/VDR to control the length of a momo stable pules, or a VCO to trigger a preset monostable at different times. I have been trying to find some thing to do the job for me but havn't had any luck. The VCR2N/4N/7N made by Siliconix are no longer made, and I can't find any where that stock them or any thing similar. Can any one tell me where to get hold of something which will work?