T
The Grim Reaper
- Jan 1, 1970
- 0
Part 1 - I need to count/log the number of times a 3mm red LED flashes. The
flash (on) period is very short - looks like half a second-ish, and the
period between flashes varies between 5 seconds and 2 minutes. I can't
interact with this circuit, so I've got to read it optically.
I've got a simple 741 voltage comparator setup that works OK with an LDR
(using a green, not red, LED as test input). However, I believe the
response time can be improved. Google as I might, I can't seem to find a
lot of information on phototransistors or other high speed, but cheap
optical sensors.
Any ideas appreciated.
Which brings me to Part 2; I've found what I thought was a phototransistor
in my pile of spare bits - photos here:
http://www.grsoftware.co.uk/PhotoTransistor.jpg but I can't for the life of
me find any specs on this part, and I can't even remember where I got it
from!!
The numbering on the side is R8305462T102. For an idea of scale, it's the
same size as a BC107 (T 192 case?!).
There is no base connector... I tried wiring it up as a simple input (in the
same circuit, replacing the LDR) but get no change in voltage, resistance or
current from any legs!! Think it's bust?!?
Again, any ideas appreciated!!
Thanks
__________________________________
The Grim Reaper
flash (on) period is very short - looks like half a second-ish, and the
period between flashes varies between 5 seconds and 2 minutes. I can't
interact with this circuit, so I've got to read it optically.
I've got a simple 741 voltage comparator setup that works OK with an LDR
(using a green, not red, LED as test input). However, I believe the
response time can be improved. Google as I might, I can't seem to find a
lot of information on phototransistors or other high speed, but cheap
optical sensors.
Any ideas appreciated.
Which brings me to Part 2; I've found what I thought was a phototransistor
in my pile of spare bits - photos here:
http://www.grsoftware.co.uk/PhotoTransistor.jpg but I can't for the life of
me find any specs on this part, and I can't even remember where I got it
from!!
The numbering on the side is R8305462T102. For an idea of scale, it's the
same size as a BC107 (T 192 case?!).
There is no base connector... I tried wiring it up as a simple input (in the
same circuit, replacing the LDR) but get no change in voltage, resistance or
current from any legs!! Think it's bust?!?
Again, any ideas appreciated!!
Thanks
__________________________________
The Grim Reaper