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Well "Signal will be connected to GPIO..." so I thought it was obvious I need 5V or 3.3V as logical 1. Singnal swings nicely between -0.05V - -4.90V
How should I connect the photodiode to get positive voltages. Does "differently" simply mean opposite direction?
I got my test circuit up and running. I used the schema whit 6.8M resistor and produced -5V rail with LTC1046.
But why I got negative voltages from output? I cant use negative voltage.
Actually I don't even know how to apply bias with op-amp, but if the simple schema you provided will do the trick I will return with lots of smileys :)
Farnell could provide only AD8656. It has 2x AD8655 op-amps in one package. Could this second op amp be easily used to improve the circuit?
Ahaa. Gain and bandwidth are bound together, so higher gain means lower bandwidth and lower bandwidth grater feedback resistor and greater resistance greater latency. I learn!
1) But in this circuit there is no 20V reverse voltage. Doesn't that make photodiode considerably slower?
2) Does V3...
I simply want to detect an edge of IR light field => digital output. Signal will be connected to GPIO of Altera DE2 FPGA board.
This was the image of suggested op amp circuit from electronicdesign.com by Bob Pease. Calculations for capacitors and resitors were not for switch but for analog...
This is to get 2 posts to be able to add a link :P
---------- Post added at 22:49 ---------- Previous post was at 22:48 ----------
Hmm.. capacitanse.. load.. transimpedance... my circuit and 10Mohms was just trial and error.
OK I lower my demand to 1us! 8) ..let's tweak later.
Photodiode...
Hello, Im looking for help to the following problem:
Im sending timing signals with directed narrow angle IR leds. When IR LED switches on I should detect signal with +5V or +3.3V GPIO pin. Most important is to get constant time, lets say±10ns, between IR present and detection. It wouldnt hurt...
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