I need to create one of those simple heart monitor you can put on your fingers. All the information is right here in the link and the LabView code is already finished, but I'm an idiot so I don't understand how I'm supposed to make the hardware. Which is pretty stupid because you only need a led, a photoresistor, a shunt resistor and some type of filter which I don't understand.
Can somebody help me?
http://www.ni.com/white-paper/14248/en/
>>997661
Lemme just google all that for you real quick ...
>>997668
I can pay $80 for anyone willing to help
>>997661
google potential divider for an ldr/shunt resistor circuit.
google passive bandpass filter
Capacitors pass AC and block DC, so if you have a capacitor to 0v it will short out AC effectively blocking it. a capacitor between input/output will block DC from reaching the output but pass AC to the output.
You should do a little research on signals if you want to learn more, look into fourier etc, all signals are made up of combinations other signals etc.
this is my favorite calculator:
(google okawa filter)(fuck you 4chan)
a bandpass is just a high pass plus a low pass so you can calculate the transfer functions separately.
the wavelength (color) of the LED is apparently very important so if you don't get a decent signal bare this in mind. there are many colors of red.
you could cheat and buy or borrow a ready-made sensor from some used exercise machine. i have several acquired that way. some work with fingers, others clip on your ear for hands-free fapping.
>>997686
>the wavelength (color) of the LED is apparently very important
Not really, unless you want to measure oxygen saturation. In that case it's important because you can use published equations/tables/curves for converting the measurements to oxygen levels.
IR leds work pretty well in basic pulse measurement, assuming you use a photodiode as a sensor. I'd assume a big part of that is that the IR leds are generally rather bright. Afaik normal photoresistors are quite insensitive to IR, so they might need red or even yellow led. In the olden times people used incandescent lamps.
>>997661
>I don't understand how I'm supposed to make the hardware.
In the simplest form it's just a photoresistor (or photodiode/phototransistor) in series with a fixed resistor, fed from a power supply and measured with an ADC. Without any filters you'll get plenty of baseline wander, but if this is just some quick test out of curiosity, you can live with it. Filter shit in software afterwards. Same with high frequency noise. Also, turn the lights off when measuring.
Note that the commercial sensors like in your pic use photodiodes almost invariantly. Photodiodes have much, much weaker output than photoresistors, requiring you to use much bigger resistors. They're also more sensitive to noise.
>>997675
What kind of information are you looking to read? Because for that money you could buy a good polar watch...
>>997704
I need the physical circuit to connect to an arduino and I need the Labview blockdiagram to translate a serial output like "Va12Vb0" to something that labview can understand (Va = 12V, Vb = 0V) using VISA. That's it. The rest of the Labview processing is already in the link above.
>>997717
In fact, everything is in the link above. I just a need a non-idiot to spell it out for me.
>>997661
instead of a photoresistor, this one uses a ir phototransistor
https://www.tindie.com/products/rajbex/easy-pulse-sensor-based-on-photoplethysmography/
>>997675
If you're going to pay that much just buy one from banggood, pretty sure I saw them last week on there.
>>997661
a pulsometer is like an led and a light sensor. this may come as a shock to you, but your heart is pumping blood with every pulse. this means your finger goes more red as it gets flushed with fresh blood. the amount of red light reflected back is measured using the photodiode. this way you can actually measure the pulse when it occurs. just use a wave form analyser like the Fourier Transform in the math library to count beats
