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by Burngate
Mon Dec 09, 2019 7:00 pm
Forum: General discussion
Topic: How does the Raspberry Pi work?
Replies: 17
Views: 287

Re: How does the Raspberry Pi work?

This question is somewhat similar to "how does a tipper-truck work?" To both, the answer will depend on your assumptions, and where you're starting from. So, for the tipper-truck, can we assume you know how an internal combustion engine works, and tell you about the high-pressure pump that feeds the...
by Burngate
Mon Dec 09, 2019 6:39 pm
Forum: Automation, sensing and robotics
Topic: Dimming a 0-10v dimmable light Problem
Replies: 3
Views: 135

Re: Dimming a 0-10v dimmable light Problem

I've watched your video several times, and I'm still convinced that mahjongg is right. When the output of the amplifier is unconnected, it goes all the way to 0v When you connect it to the lamp, it rises to 0.5v or thereabouts. So the amplifier is unable to pull its output down to 0v and at the same...
by Burngate
Mon Dec 09, 2019 10:59 am
Forum: Beginners
Topic: Connecting 5V pullup to Pi GPIO
Replies: 20
Views: 446

Re: Connecting 5V pullup to Pi GPIO

Well, draw a better one! Text sucks for drawings, which was probably why woodcuts lasted far longer than Caxton would have expected. But creating a woodcut is difficult and time-consuming, even though the forum can handle the out-put image. I was intending the o- to be the physical bit of wire, with...
by Burngate
Mon Dec 09, 2019 10:16 am
Forum: Beginners
Topic: Connecting 5V pullup to Pi GPIO
Replies: 20
Views: 446

Re: Connecting 5V pullup to Pi GPIO

... but can I safely make the assumption that it might as well be a physical 100MOhm resistor in series with the input? Possibly. But the pull-up is before that notional 100M resistance. ----5v | - | | | | 20k | | - | ---- o--------| |----> ---- 100M
by Burngate
Sat Dec 07, 2019 10:40 am
Forum: Beginners
Topic: Connecting 5V pullup to Pi GPIO
Replies: 20
Views: 446

Re: Connecting 5V pullup to Pi GPIO

Putting the Arduino pin in OUTPUT mode is another matter - if this is likely to happen a 10kΩ series resistor will provide adequate protection Read Mahjongg's post. ... you only need a microscopic current flow from a >4V source to trigger a latch up. A 10k series resistor would allow 100μA to flow ...
by Burngate
Fri Dec 06, 2019 11:54 am
Forum: Automation, sensing and robotics
Topic: GPIO resister ladder in the fart detector project
Replies: 3
Views: 152

Re: GPIO resister ladder in the fart detector project

Warning: I've not read thoroughly the Project sheet, so what follows is just guesswork. That red line you're complaining about, that should be straight but wiggles - it's a classic symptom of getting your binary digits mixed up. fart_screen1.png The second half is just a repeat of the first half but...
by Burngate
Thu Dec 05, 2019 11:29 am
Forum: Beginners
Topic: How to use the 5V power pins on the Raspberry Pi 3B+
Replies: 2
Views: 94

Re: How to use the 5V power pins on the Raspberry Pi 3B+

It might be worth having a look at https://www.raspberrypi.org/documentation/hardware/raspberrypi/schematics/README.md , in particular (in your case) the diagram for the 3B+ https://www.raspberrypi.org/documentation/hardware/raspberrypi/schematics/rpi_SCH_3bplus_1p0_reduced.pdf Although much is miss...
by Burngate
Thu Dec 05, 2019 10:18 am
Forum: Beginners
Topic: Hall effect sensor
Replies: 20
Views: 463

Re: Hall effect sensor

GPS coordinates are terrible for telling humans how to navigate, they also lack the ability to lend creative or emotional attachment. Also, they don't allow for continental drift. At an inch or so per year, it'll not be long (in relation to the age of her house) before emma1997 is getting her neigh...
by Burngate
Thu Dec 05, 2019 10:02 am
Forum: Automation, sensing and robotics
Topic: Detecting an appliance is in use
Replies: 30
Views: 712

Re: Detecting an appliance is in use

Neutral and ground are strapped together in the cellar and either can provide the same current. Dating from 1890, my house is only a bit over half the age of yours, so no problems with Historical societies. But ground and neutral are strapped where it enters the property. The earth should be able t...
by Burngate
Wed Dec 04, 2019 6:39 pm
Forum: Automation, sensing and robotics
Topic: Detecting an appliance is in use
Replies: 30
Views: 712

Re: Detecting an appliance is in use

What's more, if you ever decide to install a RCD breaker in your house, for your shower or your kitchen for example, where most accidents happen, you'll have problems.
by Burngate
Wed Dec 04, 2019 6:21 pm
Forum: Beginners
Topic: Hall effect sensor
Replies: 20
Views: 463

Re: Hall effect sensor

Just to gripe... they are just labels, seems like coming up with any more than 1 scheme for them would cause more harm than good. I agree entirely. It's a bit like every town having its own street and house naming system, when we have a perfectly good latitude / longitude system that's universal (o...
by Burngate
Wed Dec 04, 2019 11:58 am
Forum: Troubleshooting
Topic: Pi 1 B+ will not boot or will not read SD. [Solved]
Replies: 13
Views: 300

Re: Pi 1 B+ will not boot or will not read SD. [Solved]

I assumed that the engineers connected the switch in case there was going to be a need for it, and only removed the connection when they began to run short of GPIOs - GPIO 47 was reassigned to the ACT LED for the B+ so that GPIO 16 could be assigned to the header. Since it's not now connected, the b...
by Burngate
Mon Dec 02, 2019 10:13 am
Forum: Beginners
Topic: GPIO Pin still output 3.3V after the ending the script
Replies: 2
Views: 129

Re: GPIO Pin still output 3.3V after the ending the script

If "OutputDevice(3)" means GPIO3 (pin 5) then there's a 1k8 pull-up on that pin (and also GPIO2, pin 3) that'll give you 3v3.
by Burngate
Sun Dec 01, 2019 9:57 am
Forum: Troubleshooting
Topic: Pi Zero W gpio pins fluctuating
Replies: 24
Views: 465

Re: Pi Zero W gpio pins fluctuating

Of note is his original statement: Another Pi Zero W works perfectly as well. So it seemingly is just this one. I think we've proved that, for whatever reason, this one is not faulty, but we've not got to the bottom of why the second one is acting differently. As for how he discovered the difference...
by Burngate
Fri Nov 29, 2019 7:07 pm
Forum: Troubleshooting
Topic: Pi Zero W gpio pins fluctuating
Replies: 24
Views: 465

Re: Pi Zero W gpio pins fluctuating

Driving to Tesco, (actually being driven by my daughter), I had a thought (that worries her - she thinks I'm maybe having a funny turn. I tell her smoke only comes out of my ears when I'm thinking, but she won't believe me) Does Python 2 or 3 disable any pulls unless told not to? But another Pi zero...
by Burngate
Fri Nov 29, 2019 11:53 am
Forum: Troubleshooting
Topic: Pi Zero W gpio pins fluctuating
Replies: 24
Views: 465

Re: Pi Zero W gpio pins fluctuating

Interesting. So the fish seem to be in a different barrel. You've proved that the OS, be-it Stretch on a Pi 2 or Buster on a Pi 4, does change the pulls. Why it should do so is a mystery to me, but then many things fall into that class. I spend most of my time on RISC OS, which almost certainly does...
by Burngate
Fri Nov 29, 2019 11:11 am
Forum: Troubleshooting
Topic: Pi Zero W gpio pins fluctuating
Replies: 24
Views: 465

Re: Pi Zero W gpio pins fluctuating

Sure, ... but AIUI, those pulls are set before any OS is booted, so unless the OS changes things or some software is run to do so, those pulls are still active. And from the way he wrote it, I understand another pristine Pi (that hasn't been connected to his rotary encoder) doesn't exhibit this prob...
by Burngate
Fri Nov 29, 2019 11:01 am
Forum: Other projects
Topic: Detecting a change in 8x8 grid of photoresistors
Replies: 3
Views: 167

Re: Detecting a change in 8x8 grid of photoresistors

Can I simply connect my grid of sensors to two 8-input analogue converters, then cycle through checking the voltage on each combo of inputs from converter 1 & converter 2? Not quite like that. Using photodiodes, you'll need to sequentially select each row of eight sensors, by for example connecting...
by Burngate
Fri Nov 29, 2019 10:24 am
Forum: Camera board
Topic: Pi Camera Cable Length
Replies: 5
Views: 156

Re: Pi Camera Cable Length

NPDedyukhin wrote:
Fri Nov 29, 2019 8:23 am
If I want to place the camera on the street, then it turns out the device itself will also have to be placed on the street?
It depends how far away the street is, but you may find it's cheaper to place a Pi close to the camera, and use very much cheaper network cable for the long distance
by Burngate
Fri Nov 29, 2019 10:10 am
Forum: Troubleshooting
Topic: Pi Zero W gpio pins fluctuating
Replies: 24
Views: 465

Re: Pi Zero W gpio pins fluctuating

I'm not sure that not setting a pull-up or pull-down would result in the GPIO floating - on power-up, the first 9 GPIOs have pull-up set, with the rest having pull-down, so unless anything else has changed that the GPIO should always have a pull of some sort. Another Pi Zero W works perfectly as wel...
by Burngate
Thu Nov 28, 2019 10:09 am
Forum: Troubleshooting
Topic: Raspberry Pi 4 Model B (Solid Green Light Fixed)
Replies: 1
Views: 98

Re: Raspberry Pi 4 Model B (Solid Green Light Fixed)

.., it's because of the card reader slot on board. It's not tight enough or it's not holding the sd card properly, causing it unable to read the sd card. I ensure you that it's not the sd card problem because I have tested 5 different sd card and different brand. At first, I pressed down the steel ...
by Burngate
Tue Nov 26, 2019 7:03 pm
Forum: Automation, sensing and robotics
Topic: Detecting an appliance is in use
Replies: 30
Views: 712

Re: Detecting an appliance is in use

DougieLawson wrote:
Tue Nov 26, 2019 6:33 pm
...
They're referring to white cables (typically a 110V cable uses white for live).
...
https://www.leadsdirect.co.uk/knowledge ... ains-lead/ says black is live!
by Burngate
Tue Nov 26, 2019 6:37 pm
Forum: HATs and other add-ons
Topic: Problem booting RPi 3A+ using 5V header
Replies: 4
Views: 209

Re: Problem booting RPi 3A+ using 5V header

Ah, so my last assumption was wrong, but that level-converter does much the same - until HV1 is pulled low, LV1 is held (by R3) at the same voltage as LV - which is either 0v if the 3v3 rail hasn't come up, or 3v3 once it has. One of the first things that happens, once 3v3 is present, is that all th...
by Burngate
Tue Nov 26, 2019 11:29 am
Forum: General discussion
Topic: Raspberry pi ecological footprint
Replies: 60
Views: 1697

Re: Raspberry pi ecological footprint

I'm probably just adding to the noise, here, but ... One of the things I like about the Pi is that it's made in an old factory that used to make TVs. That means no concrete was poured to make the Pis. Everyone goes on about how much CO2 is generated when we drive around, but apart from a couple of a...

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