This is my first post on here and apologies up front as this is a "where do I go next" plea.
My background is more HT electrics than electronics and although I learnt about electronics at uni, it is far too long ago than I care to remember, but I still recall much of the basics.
I am trying to make an optical to USB lead for my FLUKE 123 and have found a board that does most of the hard work for me in taking the TX and RX optical pulses and converts them to USB DATA so FlukeVeiw software can read it.
http://www.sparkfun.com/products/198I have purchased the following Infra-red LED and Photo transistor to couple to the scope.
http://www.maplin.co.uk/infrared-phototransistor-2252http://www.maplin.co.uk/miniature-infrared-source-2251The schematic looks like this( link is eagle format only)
http://omapalvelin.homedns.org/fluke/usb/I have substituted the LED load resistor to a 47 ohm to suit the 3.3Vdd, 1.6Vd, 40mA. requirements of the LED from my local supplier.
Unfortunately it dont work!
After a few trials and tribulations I have managed to get the photo-transistor to conduct only when there is a constant light source. The intermittent data pulses from Flukeview (verified by substituting a Green LED for the IR) don't seem to switch the Photo-transistor fully!
At this point I'm stumped.
Is the Photo-transistor to slow to acknowledge the pulses from the IR diode or are the pulses not intense enough?
What else should I try (Buy a Fluke lead at £100 and be done with it I hear you cry)