View Full Version : Question for Tom re: Ball Exit Sensors
bjjb99
04-30-2002, 07:51 AM
In the Dark Angel pressure data you've posted, there is a second curve representing output from a sensor that detects a ball exiting the barrel. I noticed that there is a very small but broad bump prior to the ball exit spike, from 4350 to around 4370 on the X axis. Any thoughts on what that bump might be? Is this instrument drift, or a measurement of a real effect?
Is the exit sensor an optically based, pressure based, mechanically based, or something else entirely? I'm curious if the pre-exit bump is the static air in the barrel, pushed out ahead of the ball. Some sensors might detect this while others would ignore it completely.
BJJB
Redkey
04-30-2002, 09:32 AM
I'm guessing it's a pressure sensor. An optical sensor would be a sharp spike... since it's either on or off.
The small bumps are noise from the pressure sensor getting vibrations from the shot cycle. In this particular case the sensor was coming loose and I didn't catch it until a few tests later. The ball exit sensor is optical.
AGD
Redkey
05-01-2002, 09:47 AM
Optical? Interesting. I've build a couple chronos using IR LEDs and phototransistors as optical gates and I get square waves out of the them. Is your optical sensor off-the-shelf or something you've built. I think I saw photos of your setup somewhere around here... I'll have to check.
BlackVCG
05-01-2002, 07:42 PM
This one?
http://www.automags.org/~TomAGD/gundyno03.JPG
Most optical sensors are pulsed to eliminate stray light. Unfortunately they can't see fast events like the ball flying by. In the pic above I was using an Omron sensor with this problem but got around it by inserting a piece of foam rubber in the end of the barrel and letting the ball shoot it out. After this pic I just used one of our ace sensor boards to see the ball go by. That is what was used in the graph.
AGD
FreshmanBob
05-02-2002, 06:40 AM
for your tests do you guys use normal paintballs or the synthetic nylon/whatever material ones? Seems like for all those tests the normal paintballs would get messy.
We only use nylon for these types of tests.
AGD
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