[sdiy] Saw core JFET mystery

[David G. Dixon]

> A drawing would help.

Here's an attempt.  Note that the comparator's ground pin (pin 1) is
connected to -15V (not shown).  The Franco resistor is the 680R one.  The 1k
resistor and 22pF cap are the reset timing components.

          Integrator             Comparator

                                    22pF 
                   Saw           ----||----
              |\    ^            |        |
        GND---|+\   |     1k     | |\     |
              |  \__|___/\/\/\___|_|+\    |
Expo I ->-----|- /  |              |  \___|
           |  | /   |            __|- /   |
           |  |/    \            | | /    |
           |        / 680R       | |/     |
           |        \           _|_       |
           |  1nF   |           +5V       |
           ----||----                     |
           |        |                     |
           | PN4391 |                     |
           |_     __|                     |
             |___|                        |
               ^                          |
               |__________________________|
                                          |
                                          \
                                          / 2.2k
                                          \
                                         _|_
                                         GND