I've been thinking about putting a pulse monitor in a ring form factor for a while, so here we go
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*****NOTE: This is NOT a medical device*****
Got another order for @oshpark
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:( I have ordered and received the boards. Anyway, I would like to get your advice on how to rewire correctly. Concerning the schematics and layout, I only have those two image files that appear on this project page. So, magnification does not work. If you were able to export image in higher resolution, or if you can share sch and brd in vector format files that might help as well. My application is to visualize heartbeats in EL screen, an will use your circuit as a front end to clearly get heartbeats.
Are you sure? yes | no
I just created a GitHub repo for the project. You can find the Eagle files there. https://github.com/hoilett/PulseFit-Ring If you want to visualize the pulse waveform, the circuit is fine as is. The waveform will be inverted. The main modification will be changing the first band-pass filter to a non-inverting amp. This was to help my comparator circuit at the end. Also, keep in mind I use PCBs as prototype boards so I usually end up tweaking resistor and capacitor values a bit until I get what I like. From messing with a similar circuit, you may need to remove the 1M resistor (R1) in the transimpedance amplifier and put a 10k-100k resistor in it's place (and then C1 accordingly for a cut-off frequency of 5 Hz). Also, you may need to change R4 to something like 1k instead of 100 Ohms.
Let me know if you have any more questions.
Orlando Thanks for the comments and the source files.
I am willing to use your board for a pulse visualization project. Got the boards from OSHPark. Is it possible to get schematics and PCB layout in a higher resolution format?
Did you already order the boards? There are a few modifications that I will need to make that I didn't notice until I started testing the boards.
I'm taking screenshots of the schematic and board files, so I don't think it's possible to get much better resolution since a lot of text is small. I usually need to zoom in to see the fine detail even when displaying on a large monitor. My suggestion would be to take screenshots of the individual parts.
I'm really interested in hearing about your project! What's your end application?
Oh and by the way, the main modification is changing the first band-pass filter to an inverting amp configuration.
We're excited to see your project progress!
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