Hi,
for mazurov:
The Ferrite bead is from Wurth Electronik. Some of these parts are available from Digikey. This part is very similar
Digikey 732-1602-1-ND
The bead is not super critical.
for tinhead:
My risetime has not been peaked. I don't have a capacitor on the collector of the transistor, only the transmission line. It opens up a much bigger question as to why the risetime on an oscilloscope looks the way it is.
If a scope had a single pole at the bandwidth frequency then the waveform would look exponential.
Oscilloscopes have been engineered to have a Gaussian Response.
Here is a SPICE model of a Gaussian Filter
![](https://www.eevblog.com/forum/projects/transmission-line-avalanche-pulse-generator/?action=dlattach;attach=38247;image)
The reponse in the Frequency Domain
![](https://www.eevblog.com/forum/projects/transmission-line-avalanche-pulse-generator/?action=dlattach;attach=38249;image)
The response in the Time Domain
![](https://www.eevblog.com/forum/projects/transmission-line-avalanche-pulse-generator/?action=dlattach;attach=38251;image)
One of the properties of the Gaussian filter is that as you reduce the risetime on the input the risetime on the output reaches a minimum. After this point the risetime on the output becomes fixed.
HP made some Transistion Time limiters based on this property. The model numbers are 15432 through 15435
Link
http://www.home.agilent.com/en/pc-1000000488%3Aepsg%3Apgr/transition-time-converters?nid=-536902323.0.00&cc=CA&lc=engWhat is interesting about this, is that the waveform from my pulse generator looks flater on a low bandwidth scope than it does on a higher bandwidth model.
The bottom line is that you should not see overshoot unless the input is overshooting.
Is there a Gaussian Conspiracy ?
![Confused :-//](https://www.eevblog.com/forum/Smileys/default/confused0024.gif)
Jay_Diddy_B