LCoder · HackerTrans

2 ปีที่แล้วdiscuss

Chome on Windows. Grab the right scroll bar and pull to the very bottom. Once at the bottom try to scroll down with mouse scroll wheel. Screen goes blank and the error appears in the console.

LCoder

2 ปีที่แล้วdiscuss

Jumped to the bottom and the page locked up. Console shows:

  Uncaught Error: Index out of range - must be less than 2^122

LCoder

3 ปีที่แล้วdiscuss

I spent years in a previous job developing acute care pressure pads like these utilizing pressure-sensitive conductive ink. The simple open/closed circuit pads shown here work well above the mattress but (depending on your mattress weight and bed frame structure) can provide false positives when placed below. We had fun stories with our first home testers where many people (me included) planted our elbows and lifted when we turned during the night. This movement was enough of a weight lift over the pad to cause the first iteration of our sensors to trigger. The ability to adjust your bed's unoccupied zero point using an analog measurement, deciding how much weight should be added (or removed) to determine a state change, and over how much time the movement occurred makes a big difference in reliability.

Near the end of my grandmother's life, she was living with my parents and a fall risk. I did this same ESPHome implementation to HomeAssistant to provide us with alerts when she got up on her own in the middle of the night, and it helped my mother sleep much better.

Side note: those other two wires the author says they "have NFI what they do" are most likely wired into the pad as a permanently connected loop. Most monitoring equipment will look for a closed circuit on those wires to detect that a sensor pad is connected correctly and the sensor wire hasn't been broken (ripped, torn, cut, etc).

LCoder

5 ปีที่แล้วdiscuss

I'm actually starting this right now with my two teenage kids who are interested in going to college for CS. We are using an esp32 instead of a Raspberry Pi, but I'm having them work through all the hardware and software requirements to get sound (I2S) output, display, WiFi, etc.

My end goal is to have them create a backend api server for syncing data to the alarm clock, and then a mobile app so they can change settings remotely. I figure it is a good learning project for them to touch a lot of disciplines (hardware, embedded firmware, circuit design and layout, 3d modeling, web services, mobile apps) to see what they gravitate towards.

LCoder

6 ปีที่แล้วdiscuss

I've been working on a phone check-in system to help small businesses social/physical distance their customers by having them wait in their cars instead of sitting in waiting rooms or standing in lines.

https://lobbly.com

LCoder

7 ปีที่แล้วdiscuss

I don't have much that can help. We started with pressure sensitive foam for our first proof of concept since it was much easier to obtain. Soon after we worked with a Chinese manufacturer to source a replacement ink. They silkscreen and cure the ink for us into the sheets we need as a component in the final assembly.

One thing I can caution you on is how finicky the inks are. Ink thickness, curing time and temperature, and abrasions to the ink can have large impacts on the responsiveness of the ink to pressure. We do a lot of software and hardware work to mitigate these inconsistencies.

LCoder

7 ปีที่แล้วdiscuss

I'm currently working on a medical product which uses pressure sensitive ink in paper thin sheets to detect presence and movement through a mattress. I think I need to grab a piece of my scraps and put this together myself to monitor our office coffee.

LCoder

7 ปีที่แล้วdiscuss

I own a domain which a lot of people on the Internet like to randomly type in when they are signing up for things. It is ridiculous how many services accepted those fake email addresses over the years and therefor how many accounts I could reset passwords for.

LCoder

8 ปีที่แล้วdiscuss

On the topic of cheap oscilloscopes, I was looking for a cheap logic analyzer when I found the Saleae Logic. Not an oscilloscope, but if you put an input into analog mode you can visualize the waveform nicely. They have a discount for non-commercial use and startups.

https://www.saleae.com/

LCoder

9 ปีที่แล้วdiscuss

Both of my local universities still have glasses available. One is giving them away free and the other is charging $1 per.

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