Blur Busters Forums

Not to rush you or anything but have you done the click delay test yet?
I'm too curious on how the G100s compares to your arduino setup.

Edit: woops, read it as "near future", my fault.

lexlazootin wrote:Not to rush you or anything but have you done the click delay test yet?
I'm too curious on how the G100s compares to your arduino setup.

flood wrote: ill take apart my g100s and compare it's button click latency against the arduino sometime far in the future

ill try it probably january next year

new setup pictures:

http://i.imgur.com/xbpbOlQ.jpg
http://i.imgur.com/flwNG6q.jpg

my circuit is basically:
photodiode => transimpedance amplifier with 1Mohm feedback resistor => non-inverting op amp with 1Mohm and 10kohm resistors for ~100 gain => teensy

there's a minor issue that's bugging me atm.

this is what the system reads as a function of time when the room is dark and no direct light from my monitors. as you can see there are 60hz spikes................. and my monitors are turned off when measuring this so there's no way this signal is from light hitting the photodiode.

the same thing happens when using the arduino leonardo with this circuit
removing the capacitors on the op amps didn't do anything. so i'm pretty sure it's usb power related.

i know quite a few of you here are more experienced than i am with electronics so i hope someone can help me with this

ok what the fuck.

so if i move the board to the side of my computer it's fine??

dam interference.......

edit:

k i'm completely spooked.
lifting the breadboard 1cm off my table eliminates the problem

edit2:

apparently placing my hand near the leads of the photodiode causes the issue...................................
i guess this is how those capacitive touch sensors work

lol, at this rate you'll make people wear electrostatically cancelling gloves while playing.

Looks good. Again, looking forward to any tests you care to perform.

wow, reminds me a bit of one of those mr bean episodes (where he had to be in a particular position in order to get tv reception)

https://www.youtube.com/watch?v=BoDXyfAUBQc

Good thing you figured this out before taking an important measurements tho

well it doesn't actually affect measurements since i'm measuring time deltas instead of absolute values and these spikes are ~3x lower than what they would need to be to cause problems

here's what the system reads when placed in my drawer, which has a hole that lets a bit of ambient light in. my ambient lighting right now is from sunlight so there's no 60hz anything from that.



the 60hz ripple is about the same magnitude as the noise.

actually i think it's not too unreasonable given the amount of amplification i have. analogRead returns a value from 0 to 1024 which corresponds to 0-5V so the 60hz signal is ~0.5V. my amplifer amplifies by 100x so ~5mv of ripple after the first stage shouldn't be too alarming perhaps

gunna using battery power just to see what happens... so i know whether the remaining noise is power related or not

still have no idea what results in 60hz spikes though

Hey flood, finally made an account just wanted to say thanks been following for a while