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by pfletch101
Tue Jul 16, 2019 12:23 am
Forum: Automation, sensing and robotics
Topic: 'Uninteruptible' Power Supply
Replies: 2
Views: 64

Re: 'Uninteruptible' Power Supply

I've set up my pi to be able to directly plug to 120vac by using a step down converter to get a constant 5v supply. I have a 3.5V rechargeable battery hooked up in parallel and my question is: -If the pi happens to lose the 120vac supply and therefore the 5vdc, would 3.5V rechargeable battery be en...
by pfletch101
Mon Jul 15, 2019 3:38 pm
Forum: Troubleshooting
Topic: Raspberry Pi 4 temperature
Replies: 259
Views: 46753

Re: Raspberry Pi 4 temperature

Those little heatsinks make a big difference, it is the surface area that helps. They will likely make a big difference for relatively transient peak loads. However, if you are running your Pi within a more or less tightly sealed case, continuous high loads will result in the whole volume of the in...
by pfletch101
Mon Jul 08, 2019 10:24 pm
Forum: General discussion
Topic: How can I config static IP at raspberry3
Replies: 3
Views: 152

Re: How can I config static IP at raspberry3

RaTTuS wrote:
Mon Jul 08, 2019 11:15 am
hte best option is to setup the static on the dhcp server / router and not inside raspbian IMO
+5!!
by pfletch101
Sun Jul 07, 2019 8:45 pm
Forum: General discussion
Topic: How can I tell if the Pi can handle my project long term?
Replies: 8
Views: 338

Re: How can I tell if the Pi can handle my project long term?

When Heathrow Airport Terminal 5 went live, the baggage system failed. Badly. The irony was, they had made and broadcast a documentary about the baggage system tests. It was clear that the tests only loaded the system to less than the expected live load. And it was also clear that the test result w...
by pfletch101
Sun Jul 07, 2019 3:49 pm
Forum: Beginners
Topic: What cmdline do you get the most milleage out of?
Replies: 3
Views: 182

Re: What cmdline do you get the most milleage out of?

Andyroo wrote:
Sat Jul 06, 2019 9:12 pm

Code: Select all

sudo !!
The number of times I forget sudo at the start and edit a file but cannot save it :lol:
This may be obvious, but you can always save the edited file in your user space and then 'sudo cp' it back to where it originally came from. Beats starting a detailed edit again from scratch!! :)
by pfletch101
Sat Jul 06, 2019 9:25 pm
Forum: Troubleshooting
Topic: Pi 3, Yellow light bolt with official 2.5A charger
Replies: 4
Views: 139

Re: Pi 3, Yellow light bolt with official 2.5A charger

A lot of things could be the issue. The first thing I would do is disconnect the joysticks, one at a time, and also (if possible) try another monitor. If you are using a mouse and/or keyboard and didn't mention them, try disconnecting them and/or replacing them with different ones. If any of these m...
by pfletch101
Fri Jul 05, 2019 9:21 pm
Forum: Troubleshooting
Topic: sudo apt update fails hash check
Replies: 3
Views: 137

Re: sudo apt update fails hash check

I have also seen this occasionally (once about a week ago). Waiting for a couple of hours before trying again has always worked for me. I vaguely remember reading a post about a previous episode of this problem which attributed it to an attempt to update/upgrade while the archive itself was being up...
by pfletch101
Fri Jul 05, 2019 8:59 pm
Forum: General discussion
Topic: Raspberry Pi 4 Thread - general discussion
Replies: 705
Views: 59653

Re: Raspberry Pi 4 Thread - general discussion

IMHO, if you routinely run your Pis without any sort of case, you must like living dangerously! To me, that involves too much risk of random conductive material under it or dropped on it short-circuiting traces on the board, producing "Magic Smoke". :) I keep all my Pis in cases, but usually with t...
by pfletch101
Thu Jul 04, 2019 9:07 pm
Forum: Automation, sensing and robotics
Topic: Controlling an RF thermostat
Replies: 15
Views: 2197

Re: Controlling an RF thermostat

BTW, some relatively old WI-FI capable thermostats support simple REST-like API that can be easily used from any application via HTTP requests. For example, I bought thermostat in my house more than 7 years ago and it supports this API. I think that any of thermostats with trademark "Radio Thermost...
by pfletch101
Thu Jul 04, 2019 3:20 pm
Forum: General discussion
Topic: Raspberry Pi 4 Thread - general discussion
Replies: 705
Views: 59653

Re: Raspberry Pi 4 Thread - general discussion

It more that the Pi4 has everything sat at near 60C just doing nothing, the desk is not liking it so much. All the USB ports are just that hot acting as cooling (the ethernet port is cool though, it doesn't seem to aid in cooling). And the compact devices just get warm hot no matter what, it has to...
by pfletch101
Sat Jun 15, 2019 8:39 pm
Forum: General discussion
Topic: Forgot my password.
Replies: 11
Views: 589

Re: Forgot my password.

I have so many files though. I'd suggest you get in the habit of backing up work you want to save. I do it daily. I copy the tar files to my Windows PC that's also backed up daily. Even better, set up Cron jobs to do this at times when your Pi is usually running. I have a series of Cron jobs backin...
by pfletch101
Sat Jun 15, 2019 8:29 pm
Forum: General discussion
Topic: Problem with WIFI on latest full raspbian
Replies: 9
Views: 498

Re: Problem with WIFI on latest full raspbian

JFYI You can use the downloaded file as is with no need to unzip it first. Win32Disk Imager and Etcher can write to the SD card with it as is. Are you sure Win32DiskImager can use the zipped file? Yes, I verified it myself by downloading a new stock zip file. You have to tell it to look for all fil...
by pfletch101
Mon Jun 10, 2019 7:25 pm
Forum: Troubleshooting
Topic: Corrupt files within /var/lib/dpkg/info, and 'error processing package udev'
Replies: 2
Views: 125

Re: Corrupt files within /var/lib/dpkg/info, and 'error processing package udev'

I would guess that either your SD card has been corrupted by powering off without shutting down or it has reached its 'sell by date'. I would burn Raspbian to a new card and try that.
by pfletch101
Mon Jun 10, 2019 1:18 am
Forum: Raspbian
Topic: The much heralded "Buster"- When? [now!]
Replies: 28
Views: 2937

Re: The much heralded "Buster"- When?

https://wiki.debian.org/DebianBuster Are you agreeing or disagreeing with jamesh? Your linked page states explicitly that Buster is "the current testing distribution" (my emphasis). The RPF folks are, indeed, testing it. In due course, after the stable version is available, they will release a vers...
by pfletch101
Mon Jun 10, 2019 12:56 am
Forum: General discussion
Topic: Packages installing in wrong folder in Raspberry pi 3
Replies: 5
Views: 271

Re: Packages installing in wrong folder in Raspberry pi 3

I always thought you had to CD into the installation directory before downloading and installing? (or move the file to the target directory before installing) If you use pip, pip3, or apt (or apt-get, which is almost a synonym for apt), your files will be installed in the location which the utility...
by pfletch101
Fri Jun 07, 2019 9:58 pm
Forum: Raspbian
Topic: Is Rasbpian legal in the USA?
Replies: 16
Views: 972

Re: Is Rasbpian legal in the USA?

klricks wrote:
Fri Jun 07, 2019 9:55 pm
No...
I think/hope that you are answering the OP's second question, rather than the one in his 'Subject'!!!
by pfletch101
Fri Jun 07, 2019 8:50 pm
Forum: Python
Topic: Running multiple while true loops
Replies: 5
Views: 294

Re: Running multiple while true loops

Just to increase complexity: modern concepts are asynchronous. See https://docs.python.org/3/library/asyncio.html A quick scan did not tell me what asyncio was doing 'under the hood', but it is presumably either using threads or subprocesses (or both) and providing a 'wrapper' round them. As I note...
by pfletch101
Fri Jun 07, 2019 3:36 pm
Forum: Python
Topic: Running multiple while true loops
Replies: 5
Views: 294

Re: Running multiple while true loops

More complex answer: Use threads. One while loop per thread. Hit the python docs and your preferred search engine for more info on threads in python. Slightly more complex answer, still: use multiprocessing. The problem with threads in Python is that a single process can only have one thread active...
by pfletch101
Mon Jun 03, 2019 6:53 pm
Forum: General discussion
Topic: Switch for different power sources?
Replies: 6
Views: 232

Re: Switch for different power sources?

Hi! Thank you very much for your answers! That's very kind of you! In my scenario the Raspi doesn't have to run without interruption. That should make it easier. I want to be able to switch and switch it on afterwards. In some ways, it makes it slightly more difficult, since you need to provide for...
by pfletch101
Sun Jun 02, 2019 9:51 pm
Forum: General discussion
Topic: Switch for different power sources?
Replies: 6
Views: 232

Re: Switch for different power sources?

This will be difficult if the 'power supply' is feeding directly into the Pi, since only a small, very transient voltage drop can be tolerated at the Pi's power feed. If I wanted to do this - e.g. to have a Pi running primarily on solar power but with mains or a battery as a secondary power source, ...
by pfletch101
Sat Jun 01, 2019 9:00 pm
Forum: Raspbian
Topic: Access the hwrng.bin file (random number generation)
Replies: 5
Views: 315

Re: Access the hwrng.bin file (random number generation)

Thank you so much! It did cost me so much time but its finally starting to work out haha! So simple but you have to know .. This treats the binary file or the output of the urandom device as a byte stream (which is basically what it is - actually a bit stream). I think that the OP may be looking fo...
by pfletch101
Sat Jun 01, 2019 5:26 pm
Forum: Python
Topic: Trying to make a speedometer using hall effect sensor and a neodym magnet
Replies: 7
Views: 333

Re: Trying to make a speedometer using hall effect sensor and a neodym magnet

I am not asking if you can guarrantee that 10KHz would be enough at hight speeds... but do you THINK it would work.. or do I need better resolution? There are two aspects of frequency response that you need to think about. One is the number of activations a second that the sensor can deal with. Tha...
by pfletch101
Fri May 31, 2019 3:10 pm
Forum: Raspbian
Topic: Access the hwrng.bin file (random number generation)
Replies: 5
Views: 315

Re: Access the hwrng.bin file (random number generation)

You can convert binary files to hex numbers using hexdump. This 'cat's the urandom devices through hexdump to make it human readable. cat /dev/urandom | hexdump Or in your case hexdump hwrng-data.bin This treats the binary file or the output of the urandom device as a byte stream (which is basicall...
by pfletch101
Thu May 30, 2019 3:38 pm
Forum: Beginners
Topic: Fish Tank Temperature Monitor - Pi Zero - Thermistor
Replies: 17
Views: 714

Re: Fish Tank Temperature Monitor - Pi Zero - Thermistor

The fundamental problem you are facing is that the Pi has no analog inputs. So, somewhere between the thermistor and the Pi you need an A/D converter. ….or you can use the workaround that can be found in a number of temperature sensor projects - determine the time that it takes to charge or dischar...
by pfletch101
Wed May 29, 2019 8:58 pm
Forum: Troubleshooting
Topic: Apt-get update running very slow?
Replies: 9
Views: 1372

Re: Apt-get update running very slow?

DougieLawson wrote:
Wed May 29, 2019 12:46 pm
That is 100% normal when the raspberrypi-kernel package gets an update.
Text about diversions is usual under those circumstances, but I've never seen an update take anything like half an hour.

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