Finding the Right VCR/VDR or VCO to Make a Variable Length Pulse

AI Thread Summary
To create a variable length pulse, a VCR/VDR or VCO is needed to control the timing of a monostable pulse. The user has struggled to find suitable components, specifically noting that the Siliconix VCR2N/4N/7N series is discontinued and unavailable. Suggestions include using a triangle wave with a comparator or a 74HC4060 with crystal and decoding logic. The user has also discovered a method to construct a VCO using a 4046B. The discussion emphasizes the challenge of sourcing appropriate components for pulse generation.
madmike159
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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 anyone tell me where to get hold of something which will work?
 
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Triangle wave fed into a comparator with an adjustable reference.
 
or a 74HC4060 with Xtal and a little decode logic...
 
Thanks for the help guys. I found a way to make a VCO from a 4046B.
 
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