i2pi

I added some more context in the title here.

A YouTube machinist goes through how he learned an HDL and got his customer microprocessor taped out and working.

Love this!

(void) space. :P

Given that this is HN, I should add that I used the wonderful ray-optics Python package for doing the optical design: https://ray-optics.readthedocs.io/en/latest/

I was challenged to make a lens for a friend without buying any new optical elements. I have a pile of glass that I've salvaged from old camera lenses that I've modified. I wanted to make a cooke triplet but didn't have any negative elements on hand where I precisely knew their characteristics. I then realized that my eye glasses are relatively well characterized negative lenses, so I had an optometrist cut them into a disc shape and I built the lens around that. It performed very well in my simulations, but not so well in real life. But it was a fun project and my friend ended up with a unique lens for her camera.

Now try 430Hz.

As someone who has just moved back to Australia after ~20 years in the USA, I was surprised to notice how many people reverse park here. It seems to be an ego thing , particularly when I notice how many people do it at the supermarket, where it has to be super inconvenient.

Muscle movements, think talking, chewing, or blinking, generate voltages orders of magnitude higher on the scalp than sources from neural activity inside the skull.

I'm the CTO at Seer Medical, we make a wearable EEG device that's designed to be worn for ~10 days, including during sleep.

Totally agree that the electronics is not the difficult part (battery management, and power consumption aside). Our most loved features are the industrial design and materials science around our electrodes and ways of attaching them to the scalp.

Really fantastic interview with Uri here at The Amp Hour: https://theamphour.com/599-an-interview-with-uri-shaked-wokw...

It's quite a contrast to their previous interview with the creator of LTSpice: https://theamphour.com/196-an-interview-with-mike-engelhardt...

You can read more about the underlying algo here: https://medium.com/seer-medical/finding-patterns-in-seizure-...

Happy to answer questions about anything seizures, epilepsy, or med-tech related.

The gold standard for BP measurement is direct measurement via an arterial catheter - an invasive and relatively risky procedure.

For a device to be approved as a Class 1 medical device for blood pressure measurement, the FDA wants +/- 3mmHg to an established BP measuring method.

I'm the CTO at a relatively well established medical device company (EEG/ECG). Before I arrived at my current company I spent a year of my own time tinkering in the BP space. The article, while relatively, light on details gives a pretty good sense of the problem with trying to replicate the traditional BP measurements using the optical methods used by smartwatches.

Smartwatches and similar devices use photoplethysmography (PPG) to measure blood oxygen saturation. The heme units in blood have different reflectance/absorbance spectra depending on their level of oxygen saturation. The only difference between the fingertip pulse oxygen sensors used in clinical settings and those used in smartphones is that the clinical ones use transmission, whereas the watches use reflection. While the methods are different, they arrive at very similar numbers (+/- skin color & racial biases).

Unlike pulse oximeters of yore, smart watches can take many thousands of readings per second. And if you offset your photodiodes by a known distance, you can calculate pulse transit time, and a variety of other measures beyond just your spo2.

The challenge has been in translating these measures back into systolic and diastolic blood pressure. To be accepted by the FDA you need to be able to show that your device is +/- 3mmHg. That's just not doable right now for the reasons mentioned in the article.

That said, the measures that you can get from high-speed PPG are probably not useless. But these measures aren't backed up ~200 years of medical practice. It is a very long road to introduce new measures into the medical system. Not only do you need to get FDA clearance to sell your device, but you need to navigate the reimbursement system to find someone who will pay for your device. Doing this in a 5 year time span would be unheard of. While cardiologists would like a better system than cuff based BP measurement, the upside of a better system is limited by the current medical system. And there's a significant cost and downside risk to anyone pushing for something different.

One company that I spoke to and is still working on the problem comes with an impressive biomedical pedigree, and they're starting in the non-diagnostic "wellness" space.

Another company is using mm-wave radar to measure pulse waves in a different way, but it appears that they've pivoted from being directly challenging the BP status quo into now selling their hardware sensors to more well established medical device companies.

Long story short, I'd be impressed to see blood pressure cuffs retired in my lifetime.

We have p2p wifi between our barn and farm house. The barn is powered by solar.

I use engenius WAPs, a 100Ah battery, 2 100W solar panels, a $15 solar charge controller, various buck/boost converters for other power requirements. The system also powers an LTE repeater and LTE modem, to provide the farm with internet access.

Feel free to make it with Lead Free solder. See RoHS standards: https://en.wikipedia.org/wiki/Restriction_of_Hazardous_Subst...

The standards are now much higher, which may be limiting demand. It is far less attractive to apply for a new charter when your growth is curtailed and examinations are more intense and frequent for your first _seven_ years of operation.

You're right on the prior to 2008 comment, but it was indicative that any bum and their mortgage broker could get a charter. But tech companies who are (hopefully?) less shady, can't.

Money transmission laws are irrelevant in this case. Standard Treasury was never keeping customer cash on their balance sheet, they were enabling APIs for banks.

If you're a payments business and cash passes through your balance sheet, then transmission regs apply.

If you're moving bits, but not money, they don't.

And if you have a bank charter, or bank sponsorship, you're mostly exempt from them.

De Novo charters are available, but in very limited supply. I think there have been maybe 5 new charters since the crash. Prior to 2008, 100's were issued annually.

The problem with acquiring an existing bank is that for any tech company, you are likely to be changing the business purpose of the acquired bank, so you'll need to basically go through the de novo process again.

Either way, you're looking at 5+ years to get a charter that you can use to run any new digital banking business.

And then there are the capital requirements. The capital required to launch a Bank is tremendous. You need to have sufficient capital against your projected future deposits. Way out of the range of VCs. And only a limited number of PE firms play in that space.

And even if VC's did have the financial resources, the returns are dismal. Chartered banks, particularly new charters (either de novo, or acquired for a new business purpose) are limited in their growth. A very fast growing bank might grow 50-100% yoy. The return on capital equation just doesn't work out for VC capital.

It doesn't make much sense either for PE firms, given the limitations imposed by the Bank Holding Company Act.

tl;dr, this shit be hard.