Recent content by doofus

Thank you both for the links. I'm learning a lot. Now that I think about it, I never considered how a useful ADC worked beyond the toy model ones. Interesting

Not off base at all. Most of the post is me failing to ask for examples like this because I lack the vocabulary and clarity of thought. Super cool! I take it your ADC had a transistor that only read off the measurement when trigger went high? I like this because it shows that you only need a...

This helped me a ton thank you. For some reason I couldn't see what the best way to do this was. So I guess for a single pixel, in the 4T version we wouldn't need that SEL transistor because we aren't selecting rows at all. Making the simplest unit that stores charge a 3T with a capacitor...

What I still haven't been able to figure out, and maybe its deserving of a new Doofus post is, what does the "simplest" circuit for this look like? I am not an EET, haven't even played one on TV, but what I don't understand is how I could close a switch for example and dump charge stored up from...

That would be part of the problem with my searches, to be fair though looking for "charge device" in google probably isn't going to be very helpful either :P. For some reason PhotoVoltaic's didn't cross my mind as a search term. Thanks for this

True! Its a little limiting in some characteristics. For example, if someone wants a high ADC count, you may be buying a lot of unused functionality that goes unused. Its still a good point and worth making.

Thanks Tom.G I am a fan of LMGFY as well :D. The link is cool. I love the diagrams. Here's what I still don't "know" yet. How is charge stored with an open circuit? Most photodiodes have relatively speaking very low capacitance. Often by design, because high capacitance loads are difficult to...

Thanks Bob, that's pretty enlightening. How do CMOS image sensor pixels "store charge" to be read out later?I'm somewhat familiar with op-amps and amplification of photodiode current in general, but I am curious how CCD and CMOS pixels have a concept of "exposure".

Sorry this is my ignorance. I am referring to CMOS imaging sensors because I am uncultured and unaware of their other use cases. I'm specifically interested in what the smallest unit is, and if its possible to build/purchase for low light level measuring. Where I can learn more about this, or...

The idea on its surface is goofy. The use case isn't for taking images, more-so for a typical photodiode like application. But, the nice thing about being able to store charge from light exposure is, well, assuming thermal noise and other-wise are OK, you could measure low light levels without...

I was thinking about how CCD's and CMOS's almost exclusively come in multiples. To be clear, what I am referring too is how each chip is fabricated to feature many pixels. Does the fundamental unit of a CCD/CMOS have a name "commercially"? Something like a "single pixel camera"? Looking at...

Cool software. I see, so you think the effect is due to aberrations. Makes more sense then violating laws of physics. I could put an aperture before the collimating lens. Sad to see some light intensity go, it isn't very bright to begin with, but, I now see the issue in the physical sense...

Yes sorry, coffee has not entered my blood-stream yet. I edited the above post.

Correct, the slit image's longest dimension(4mm) is orthogonal to the dispersed image. I revisited this issue and my original belief that light was escaping the cut edges of the prism is incorrect. I can reproduce this effect if my objective lens is plano-convex. Biconvex* lenses do not focus...

Thanks for your help on this. My set up is nearly identical to the diagram you've drawn, just a larger incident angle on the prism. The light is collimated to about a meter in length with <1mm divergence in radius in the horizontal plane. Something you said resonated. I reset the prism so that...