Waveshaper
The "5Pulser" waveshaper produces a train of pulses whose number (and widths) are varied with a control voltage. At the lowest control voltage a single square wave is put out, whereas at the highest voltage a train of 5 pulses spanning less that half of the total wave period is produced.
www.elby-designs.com/webtek/panther/panther.htm
Available as an assembled module and as a DIY project.
This module is currently available.
$132