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by Burngate
Thu Aug 08, 2019 8:51 am
Forum: General discussion
Topic: A question about the Raspberry Pi 4 PCB layout
Replies: 21
Views: 999

Re: A question about the Raspberry Pi 4 PCB layout

Imperf3kt wrote:
Wed Aug 07, 2019 10:08 pm
... heat rises.
Only in a fluid, and then only in a gravitational field.

The Pi is solid. Heat spreads by conduction, without the help of gravity.
It's only after it reaches the air that convection starts to be important.
by Burngate
Thu Aug 08, 2019 8:20 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: current, voltage signal output raspberry pi
Replies: 4
Views: 167

Re: current, voltage signal output raspberry pi

So I was not far off with frog's legs. The device you for-instanced doesn't seem to be extremely fast, with times in the several microseconds being mentioned, so a Pi should be able to do what you want. To create a variable signal between -8 V and +8 V @ ±20 mA (that's up to 160mW) you'll need an AD...
by Burngate
Wed Aug 07, 2019 5:28 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: current, voltage signal output raspberry pi
Replies: 4
Views: 167

Re: current, voltage signal output raspberry pi

To be able to help, we would need more details. What are you wanting to stimulate? Galvani's frog's leg experiment has very different requirements compared to ... (insert name of experiment here) The Pi's GPIOs (General Purpose Input / Output) work at 3.3V, can give upto a few milliamps, and can tog...
by Burngate
Wed Aug 07, 2019 10:45 am
Forum: Troubleshooting
Topic: i cant find python on my pi
Replies: 5
Views: 206

Re: i cant find python on my pi

Are you by any chance as old as I am? Because that's the sort of question that would have puzzled me, back then. My first encounter back then was with something on the far end of a telephone line; I had to dial the right number and jump through the right hoops, then I was presented with a BASIC comm...
by Burngate
Sun Aug 04, 2019 10:11 am
Forum: Beginners
Topic: [SOLVED]Pi4B: 5V brushless fan on 3V3 pin?
Replies: 17
Views: 526

Re: Pi4B: 5V brushless fan on 3V3 pin?

Actually, a brushless DC motor isn't primarily an inductor, in that it has electronics built-in to provide the commutation that brushes would be needed for. And, anyway, even a simple brushed motor acts as a generator when the power is removed, generating a voltage in the same direction as the power...
by Burngate
Sun Aug 04, 2019 8:47 am
Forum: Beginners
Topic: Need guidance on very specific LED use-case
Replies: 7
Views: 345

Re: Need guidance on very specific LED use-case

In reverse order: I am not sure if I can use a 5 V or more power supply for the rpi It must be 5v - no more, no less. (Within 0.25v of 5v, to be precise) I think that the rpi zero W would talk to the LED strip directly assuming I plug the LED strip end(s) correctly onto the GPIOs. Is that correct? Y...
by Burngate
Sun Aug 04, 2019 8:29 am
Forum: General discussion
Topic: Request for a new folder: Low Power & Solar
Replies: 35
Views: 1111

Re: Request for a new folder: Low Power & Solar

19 posts (so far) by 8 people - 1 dead against, 2 possibly con, and 2 for. If democracy ruled, DougieLawson would be Emperor. rin67630 started it, and isn't going to give in without a fight. DougieLawson's going to fight with whatever weapons he can find, however blunt. So far, they've been as blunt...
by Burngate
Sat Aug 03, 2019 5:37 pm
Forum: General discussion
Topic: Request for a new folder: Low Power & Solar
Replies: 35
Views: 1111

Re: Request for a new folder: Low Power & Solar

Why pick on Wolfram? (the last post isn't yet a month old) And "You won't get enough traffic to sustain it." is a specious arguement - a bit like not wanting to building a road to a village because not many people live there. Surely the General folder, with 36985 topics, is ripe for subdivision, jus...
by Burngate
Fri Aug 02, 2019 9:40 am
Forum: Beginners
Topic: Control 12v Fan with separate PWM Pin, Doing it right? (Will it Kill it?))
Replies: 7
Views: 260

Re: Control 12v Fan with separate PWM Pin, Doing it right? (Will it Kill it?))

https://noctua.at/media/wysiwyg/Noctua_PWM_specifications_white_paper.pdf Well, with that, we can get somewhere! Since you're not using the tach signal, you can ignore the rubbish on the fourth page about it being in Hertz so needing to multiply and divide. Page 6 says "External pull-up is not nece...
by Burngate
Thu Aug 01, 2019 6:09 pm
Forum: Beginners
Topic: Control 12v Fan with separate PWM Pin, Doing it right? (Will it Kill it?))
Replies: 7
Views: 260

Re: Control 12v Fan with separate PWM Pin, Doing it right? (Will it Kill it?))

Couple of notes: Tried looking for details of how to drive that fan, but came up with zilch. So I have no idea whether it includes its own pull-up or to what voltage. From your description, I tried to remove the 4.7k Resistor, does not seem to change anything. Fan Spins and can control it. it would ...
by Burngate
Wed Jul 31, 2019 5:33 pm
Forum: Official Foundation Display
Topic: Raspi4 + official touchscreen display: power solution
Replies: 7
Views: 546

Re: Raspi4 + official touchscreen display: power solution

Apparently the Pi 4B doesn't have that polyfuse, so power into the USB-C is the same as into the GPIO header, as far as the Pi's concerned
by Burngate
Tue Jul 30, 2019 5:59 pm
Forum: Troubleshooting
Topic: 3B+ suddenly died with no video out and solid act led
Replies: 10
Views: 297

Re: 3B+ suddenly died with no video out and solid act led

I did put a 51Ω resistor in the circuit. I guess that's not enough to limit the current to a safe level. A GPIO can safely provide 16mA. 16mA through 51Ω would mean about 0.8v across it, so the LED would have to have 2.5v across it. There's a nice graph in Kingbright's spec. sheet for their L9341 h...
by Burngate
Tue Jul 30, 2019 9:47 am
Forum: General discussion
Topic: Fan header pins?
Replies: 25
Views: 1060

Re: Fan header pins?

ProDigit wrote:
Tue Jul 30, 2019 12:25 am
Has anyone tried or verified if the caps can blow when bridging 3,3V and 5V?
Mahjongg has already explained why you shouldn't do it, and it's got nothing to do with caps.

But you may find it an interesting experiment to over-voltage a capacitor. Just keep your fingers away from it.
by Burngate
Tue Jul 30, 2019 9:08 am
Forum: Troubleshooting
Topic: 3B+ suddenly died with no video out and solid act led
Replies: 10
Views: 297

Re: 3B+ suddenly died with no video out and solid act led

GPIO -> Led + GND -> Led - You need a resistor between the GPIO and the LED (or between the LED and GND) to limit the current. Too much current can damage the GPIO circuitry inside the SoC, and that damage can spread. LEDs are not straight-forward devices - up to a certain voltage, almost no curren...
by Burngate
Mon Jul 29, 2019 6:32 pm
Forum: Troubleshooting
Topic: 5V GPIO Pins not working
Replies: 4
Views: 117

Re: 5V GPIO Pins not working

And of course, the Pi's GPIO header has lots of pins that don't carry GPIOs.
Nit-picking is a game enjoyed by many on this forum, as you'll no doubt find out if you hang around long enough. It makes us old guys feel superior, and will give you a small frisson of joy when you find you also can join in.
by Burngate
Mon Jul 29, 2019 6:28 pm
Forum: Troubleshooting
Topic: 5V GPIO Pins not working
Replies: 4
Views: 117

Re: 5V GPIO Pins not working

... UCTRONICS GPIO pin breakout kit ... That appears to be a 40-pin ribbon, T-cobbler and breadboard. Are you sure you have the ribbon connected to the Pi correctly? There are two possible orientations, one of them wrong! I'm not sure what you mean when you say "all of the pins on the 5v side" Ther...
by Burngate
Mon Jul 29, 2019 5:50 pm
Forum: Troubleshooting
Topic: 3B+ suddenly died with no video out and solid act led
Replies: 10
Views: 297

Re: 3B+ suddenly died with no video out and solid act led

I previously connected a led and a buzzer and everything worked just fine until I tried to boot it up yesterday. How did you connect those? Taking too much current from a GPIO, or letting more than 3v3 near a GPIO can damage the SoC https://www.raspberrypi.org/forums/viewtopic.php?f=28&t=58151 is u...
by Burngate
Mon Jul 29, 2019 9:46 am
Forum: General discussion
Topic: Test results - Pi 4 as a desktop computer
Replies: 2
Views: 300

Re: Test results - Pi 4 as a desktop computer

Gavinmc42 wrote:
Mon Jul 29, 2019 2:01 am
Could not spot Nessie, plenty of speed boats in the Loch.
That's 'cos she's on holiday, visiting relatives in Loch Linnhe.
She does that every year - to get away from the noise of the speed boats and the tourist crowds
by Burngate
Sat Jul 27, 2019 10:37 am
Forum: General discussion
Topic: Surge protector
Replies: 6
Views: 205

Surge protector

In the STICKY: Introduce yourself,
1Love wrote:
Fri Jul 26, 2019 9:53 pm
... but was wondering if people use a surge protector as a power switch.
I was just wondering how a surge protector could be used that way.
The ones I've found on Google don't have switches. Perhaps he/she means an RCD?
by Burngate
Sat Jul 27, 2019 9:20 am
Forum: Troubleshooting
Topic: Raspberry Pi 4 well done
Replies: 2
Views: 134

Re: Raspberry Pi 4 well done

104F is 40C; 99F is about 37C. Both well within the happy valley.

Apart from the main SoC being cooler than the board despite being the main source of heat, what makes you think you have a problem?
by Burngate
Thu Jul 25, 2019 9:32 am
Forum: Troubleshooting
Topic: RPi, grounding and capacitive touch
Replies: 1
Views: 104

Re: RPi, grounding and capacitive touch

gsr_arduino3.jpg I'm not sure what you mean by I'm using an RPi in a circuit with an Arduino to measure capacitance, a bit like a galvanic skin response system. ... given that "galvanic skin response" measures resistance, not capacitance. I'm also unsure how you're connecting that to a Pi. Perhaps ...
by Burngate
Mon Jul 22, 2019 5:34 pm
Forum: Off topic discussion
Topic: big hands
Replies: 9
Views: 1634

Re: big hands

Last time I went to collect my medication the pharmacist said I had beautiful hands. Be that as it may, they still won't fit where they need to be to undo that last PH00 screw. Putting "precision tools" into Google brings up a wealth of links - you might find some of them useful, though you can spen...
by Burngate
Mon Jul 22, 2019 5:17 pm
Forum: Troubleshooting
Topic: 1 of 6 Pis Not Booting
Replies: 5
Views: 173

Re: 1 of 6 Pis Not Booting

Have you a meter,and if so, is the 3v3 present? ... be gentle, its a Monday and theres only so much sarcasm my brain can handle :P Friday will feel better Monday mornin' feels so bad Ev'rybody seems to nag me Comin' Tuesday I feel better Even my old man looks good Wed'sday just don't go Thursday goe...
by Burngate
Mon Jul 22, 2019 10:44 am
Forum: RISCOS
Topic: How long will it take for Risc OS to be on todays level of Raspbian?
Replies: 40
Views: 2327

Re: How long will it take for Risc OS to be on todays level of Raspbian?

jamesh wrote:
Mon Jul 22, 2019 8:00 am
rpdom wrote:
Mon Jul 22, 2019 7:32 am
DavidS wrote:
Sun Jul 21, 2019 9:56 pm
Cooperative Multitasking
Is that really a good thing?
No.
Other than in situations where it is.
In which case, yes.

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