Finding someone else's algorithms would be a good idea; I belatedly realize that a bit of powerline signalling is done near zero crossings, and maybe timing peaks then resetting the peak detector at zero crossings is a better way to go. A powerline
45 MHz Ethernet link wouldn't look benign.
So, load a Windows virtual machine into a MacBook. The energy manager "schedule" settings will still work; set it to sleep soonish if only battery is available.
It's not 'when power comes back' that you set, but an internal time-of-day start time, and/or shutdown time. If power drops or not, it'll still start the next day, at the appointed time, on battery. The battery/line-power status would have to be checked by a script if you wanted any power-on event to make it reboot, and no script can startup or wake-from-sleep on condition of power inlet status.
On a sunny day (Wed, 30 Mar 2022 12:27:32 -0700) it happened John Larkin <jlarkin@highland_atwork_technology.com> wrote in snipped-for-privacy@4ax.com:
Is that not mainly a BIOS config? My laptop runs Linux, but I have specified a BIOS password, if you do not then it will boot normally AFAIK. Same for my other older small laptop, was even running as web server for years.
Use a Raspberry? I now have 5 of those in use. Some just via SSH, no monitor no keyboard, like the one used as router, Lower power use too. There exist battery backup 'shields' for those.
There are three problems, there:
- they are looking for something different than what I seek
- they are academics (with notoriously crappy implementations)
- their algorithms may not be completely specified in the literature (and CURRENT source code may not be publicly available from which to extract those "latest details/discoveries")
I was thinking do a DFT on the samples and extract the fundamental. From that, go back and "pick" whatever points you want on the specific waveforms for "actual observations".
Yes. Some big PCs have the powerup boot option in their BIOS, some don't. I've not found a laptop that does.
On a sunny day (Thu, 31 Mar 2022 07:10:37 -0700) it happened snipped-for-privacy@highlandsniptechnology.com wrote in snipped-for-privacy@4ax.com:
OK, I think when the laptop powers off by itself it is because the battery is empty it will need charging before it will boot again? I wrote some software 'xbat' that runs on my laptop that makes it beep very loud when battery is low
xbat displays battery level and time left on a charge in X. The display is updated once per second. If 3 minutes or less time is left, a 100 ms 4 kHz warning beep sounds every second. The beep function requires siggen-2.3.10 to be installed, it also requires access to the audio device. <end quote>
You could make it power the laptop down early too (say with 1 hour spare left) ~ # cat /proc/acpi/battery/BAT1/state present: yes capacity state: ok charging state: charged present rate: 0 mA remaining capacity: 4424 mAh present voltage: 16517 mV
If all else fails then a bridge rectifier and series cap driving a relay could press the power button for a second when mains comes on. But modern laptops will run for hours with mains power down, so how long are your mains interruptions?
IIRC a lot of them have wake-on-LAN in the BIOS, so you might be able to apply some router hackery to the problem. (I'm a devoted user of legacy BIOS, so I don't know a lot about UEFI things.)
Cheers
Phil Hobbs
If laptops don't do what is needed, there are a lot of mini-itx motherboards around that can be configured to auto restart and which have a single 12V dc input. If the disc drives don't use 12V, (SSDs and 2.5inch spinning drives don't) then they will usually cope with quite a wide variation in input voltage as the 12V input goes to a buck converter to generate 5V and then the other lower voltages needed. Some industrial motherboards are even rated for inputs of up to about
19Vdc. This means that a 12V SLA battery would make a very efficient UPS for such a motherboard. I have used ASRock IMB-150/151 motherboards in this way. They are rated for input voltages of 9-19V, but I think the TI buck converter chip they use is actually good for operation with up to 25V. John
It's pretty attractive to use old laptops for this sort of job--I use them as NASes, for instance. You get them from eBay for $100 or so, replace the HDD, and you're done. (I run Linux on them, so there are no huge issues with reinstalling the OS.)
Cheers
Phil Hobbs
If I understand correctly what you are trying to do, I'd suggest applying Nyquist criteria for waveform re-construction....
That's the essence of the question. *Knowing* what the line can look like and *which* aspects of the waveform carry information pertinent to making these sorts of decisions. Capturing the "entire" waveform may not be essential if it doesn't "add value" to any deductive process (e.g., simply noting the magnitude of the highest peak (captured asynchronously) might reveal more information for less effort than trying to sample it "continuously".
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