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Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
I would suggest using a silicon PIN photodiode with a clear window like BPX65
BPX65 is so good that it can even be used for individual photon counting, so have no fear over sensitivity. It is also very fast with risetimes down to 3.5 nanosecond in some configurations.
To use BPX65 - or similar, cheaper, PIN photodiodes with clear lenses - you will have to operate your spark gap in total darkness, perhaps by putting a hood over it, or by doing the experiments at night with the room light switched off!
You could mount your PIN photodiode in one end of a light-proof plastic tube (to keep the diode away from the spark field) and have the spark gap in a light proof enclosure at the other end.
BPX65 is one of those PIN photodiodes that almost went out of production, but sales have rebounded with a lot of new applications that didn't exist when it was first designed. Centronic now hold the rights in it, and its price has gone up. There are much cheaper silicon PIN photodiodes with clear windows on the market, that will work for you, though they may not have the full 1mm*1mm area of the BPX65 chip. Avoid PIN photodiodes with integral IR filtration, as these will absorb the violet and blue light of your spark spectrum.
Registered Member #4215
Joined: Wed Nov 16 2011, 09:45PM
Location:
Posts: 32
Thank you for your help. I think such fast diode detector is good solution. And what would you said for measuring voltage on capacitor with specially designed high voltage divider. Fast drop of voltage during discharge should signalize of the discharge?
Registered Member #1064
Joined: Tue Oct 16 2007, 05:04PM
Location:
Posts: 42
Why use "specially designed high voltage divider"? Just hold oscilloscope probe up in the air. There should be enough stray capacitance to obtain a display on the oscilloscope.
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What is the best method to measure spark gap frequency?
