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Infrared photodiode amplifier schematic needed

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bogdanm

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photodiode schematic

Hi all,

The short story: I'm looking for an infrared photodiode amplifier schematic that is to be used in a universal remote control project.
The long story: please note that I'm NOT looking for an integrated module (SFH5110 and such), as I don't want to have the signal from the remote demodulated. An example to motivate this: even if a SFH with an internal filter centered at 36KHz would work for a 40Khz remote control (with limited efficiency), it will definetely NOT work well for a 120-khz modulated remote control (yes, they exist, although they are quite rare). Using more SFH-like sensors with different center frequencies is out of the question, so what I want to do is to amplify the signal from an ordinary IR photodiode to TTL levels and anaylize everything in a microcontroller. Unfortunately, I'm stuck with the amplifier. While the Internet is full of SFH-based schematics, it seems that it's not so easy to find a good IR photodiode amplifier schematic. I also searched this forum, without too much luck though. I tried to use a combination of this schematic:

hxxp://www.mitedu.freeserve.co.uk/Circuits/Interface/mod_det.htm

and an active high-pass filter connected to the output of the first stage, but I'm getting a quite distorted signal and I can't use it. I also tried a number of schematics with operational amplifiers, including a variation of this one:

hxxp://www.zen22142.zen.co.uk/Circuits/Interface/irext5.htm

but also without luck. It seems that what I need is actually this (or a similar device):

hxxp://pdf.alldatasheet.com/datasheet-pdf/view/90289/ETC/SDP8600.html

But it seems that the above mentioned part is hard to find.
So, the conclusion: if you know of any schematic (or, even better, a specialized IC) that does what I need, please let me know. Thank you in advance for your help.

PS. Of course, I can use a phototransistor instead of a photodiode if this simplies things, though I doubt.
 

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