Building Jim Williams Pulse Generator - What capacitors to use?

[JoeN]

This project:  https://www.eevblog.com/forum/blog/eevblog-306-jim-williams-pulse-generator/570/

More info:  https://entangledwaves.wordpress.com/2013/07/15/avalanche-pulse-generator/ and http://zeus.phys.uconn.edu/wiki/images/Pulser_circuit_diagram.pdf

Jim William's schematic does not give voltage ratings for capacitors.  I assume it should be at least 100V, right?  My ceramic and electrolytic .47uF capacitors are 50V and tantalum ones at 35V.  What do you all suggest?  Also, do you think I can get away with 1N4937s instead of the MUR120s on the power supply section (that is what I have)?  The reverse recovery time is 150ns instead of 35ns for the MUR120 but somehow I bet it will work OK.  What do you think?  I just put some on order but I don't want to wait.

Thanks!

Is this a good choice:  http://www.newark.com/multicomp/mc1210b474k201ct/ceramic-capacitor-0-47uf-200v/dp/22T0152  200V, 10%, cheap

Actually, their price on the suggested diode is good too.  http://www.newark.com/vishay-general-semiconductor/mur120-e3-4/fast-diode-1a-200v-do-204ac/dp/76K7747   I probably will just order both and wait for the parts.

Ideas?

[Kleinstein]

The 1N4937 is OK. The switcher should not be that extremely fast.

With the first two caps one might in theory get away with 50 V ratings, but 100 V or more is definitely better.  One should not use a tantalum cap close to the maximum rating and no way well beyound that. They caps may be a littel smaller for a first test,  if the 1 M resistor is increased to reduce the pulse rate.