Homemade oscilloscope to detect PWM DIY guide
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I splurged on a Thorlabs PDA100A2 photodetector for about $450. And actually, I'm glad I did.
I'll be forever grateful to @KM and others on this thread that helped me create a DIY photodetector, but there were a few screens that seemed to be flicker free but still gave me headaches. Here's one of those screens (a supposedly flicker-free Benq). The DIY photodetector in red and the Thorlabs one in blue. Note that the oscilloscope is set to 50 microseconds per div, so my DIY photodetector just doesn't seem to be responsive enough to pick up the flicker.
Here's a couple more comparisons with a flashlight that flickers. Same colors (DIY in red and Thorlabs in blue), The Thorlabs response time is well under 1 microsecond whereas my DIY response time is roughly 10 microseconds.
If anyone wants to borrow my setup I'm sure we could work something out.
Would you be able to share some tips on how to use the Thorlabs product? I have been testing several devices for PWM and temporal dithering at the link below with a cheap photodiode and microscope. Don't think they are truly "flicker free."
https://ledstrain.org/d/2589-testing-for-non-pwm-and-temporal-dithering-displays-laptops-etc
photon78s Here's a video that I created that walks you through the whole process: https://www.youtube.com/watch?v=AoJ2jFgpBik
That should give you a pretty good idea of what to do.
I wonder if we (as a community) could do more to get people started down the path of using a photodetector and oscilloscope. Things like:
- Mass produce a bunch of the DIY detectors and sell them on eBay for like $25 (not trying to make a profit; just cover the costs).
- Produce some how-to content to help get people started.
- Establish a rental program where you could rent the equipment for a nominal fee and try it out for a few weeks.
- Engage other people on this forum to encourage them to give it a shot.
Although there are likely a lot of people on this forum that aren't sensitive to flicker, I suspect there are a lot of people who are sensitive to flicker but they just don't know how to measure it.
Very helpful video! Thanks so much.
Agreed. And also easy ways to measure temporal dithering as well with the cheap microscopes and phones many people already have or can afford.
can i just use the sound card of the laptop?
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Looking for small handheld portable scope with spectrum analyser mode because just flicker waveform is kind of stupid when radex lupin gives you spectrum view. Any made in china marvels? For decent price?