RE: In search of a good trigger point

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-uswest-dot-net>" <Gary.Lau-at-compaq-dot-com>

>Finn Hammer<f-hammer-at-post5.tele.dk>
>The reason that I would like to remain triggering on 50Hz is this: Since
>I have 3 HF_events_ per 1/2 phase, and these are bound to happen at
>slightly different initial potential (although the purpose of this
>exersize is to make them equal), If I trigger on the onset of the
>ringdown, then I`l get those 3 ringdowns slapped on top of each other on
>the scope. Since they don`t start out from the same polarity, it will 
>be hard to count transfer cycles and such. (on second thought I`l get
>all 6 ringdowns on top of each other).
>I would like to examine only one of these ringdowns, as it happens on
>one individual gap. There are some strange things happening, like the
>gaps don`t quench in the same way. Out of 3 ringdowns, one leads to the
>capacitor starting to recharge at 1 kV, whereas the other 2 start from
>0kV.

Hi Finn:

The fiber optic probe's bandwidth does not extend down to DC.  Is it
possible that when viewing within a 50Hz event, that there is a LF error
that affects the "zero" point and may cause it to appear that the cap
discharges to different degrees at the end of each bang?  As I recall (don't
have the schematic handy*), the transmitter had the signal passing through a
tantalum cap, which would cause a low frequency rolloff.  Try increasing
that cap value.

Regards, Gary Lau
Waltham, MA USA

*
http://hot-streamer-dot-com/TeslaCoils/Misc/Transmit.jpg
C201 and C202 block DC on the voltage input.
http://hot-streamer-dot-com/TeslaCoils/Misc/Receive.jpg
C101 and C102 are DC blocking caps.
I "think" the cutoff frequency was very low like 1.5Hz.
- Terry