Products > Test Equipment
Fluke 87IV please whisper in my IR :P
frenky:
I have replaced photo-transistor SFH300FA with photo-diode SFH203FA but it did not work. Signal barely dipped when IR light reached photo-diode.
I then tested setup like this:
Image source: http://www.ebay.com/itm/13-pc-INFRARED-IR-eXperimenter-Pack-LEDs-Detectors-/350727119911
An this works great standalone, connected just to oscilloscope. I'll change the code to trigger on the rising edge but it should work...
serggio:
What reason to have 200 Ohm resistor in this chain? Try to increase 22kOhm to 70 kOhm for better amplitude. Best value for bottom resistor you can always find with oscilloscope particularly for your connection speed. ;) For 9600 baud 100 K also will work well
frenky:
Not sure, perhaps for diode protection. But since arduino inputs are in high impedance state I don't think it is needed.
With 5V source and with 200ohm top resistor and 10k on the bottom I got 3.8V signal pulses while pointing TVs remote controller into it.
Which is more than enough for stable triggering.
I'll do some more tests...
serggio:
--- Quote from: frenky on April 28, 2017, 08:37:52 am ---No sure, perhaps for diode protection. But since arduino inputs are in high impedance state I don't think it is needed.
With 5V source and with 200ohm top resistor and 10k on the bottom I got 3.8V signal pulses while pointing TVs remote controller into it.
Which is more than enough for stable triggering.
I'll do some more tests...
--- End quote ---
No, no, no.... \$\Omega\$
Photodiodes work connected backward than emitting diodes. Reverse voltage 50V for your diode. No any protection resistor needed till you not reach 50V in chain.
Forget about TV remote control. There emitting diode work with high pulse currents more than 100 mA! You need focusing at emitting light power from your meter, that significant lower! ;)
frenky:
--- Quote from: serggio on April 28, 2017, 08:43:26 am ---Photodiodes work connected backward than emitting diodes. Reverse voltage 50V for your diode.
--- End quote ---
I know that. My thought was that when photo-diode starts conducting in backwards because of IR light the current from source could damage it if there was no resistor in series...
But this could only happen if you had it connected directly between 5V and ground.
I might also be totally wrong about this... ;D
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