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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: 347

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: 1762

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: 365

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: 1276

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: 365

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: 169

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: 169

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: 365

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: 321

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: 263

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: 156

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: 129

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: 2605

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: 196

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: 5926

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.
by Burngate
Mon Jul 22, 2019 9:41 am
Forum: Beginners
Topic: Using Raspberry pie to teach AI
Replies: 2
Views: 130

Re: Using Raspberry pie to teach AI

"School children" can mean age 5 to age 15, so you may need to clarify this. "Artificial Intelligence" should mean rather more than what a small (i.e. desktop) computer is capable of, and anyway isn't necessary for recognising pictures, for example, so I assume you don't really mean it. Perhaps you ...
by Burngate
Mon Jul 22, 2019 9:28 am
Forum: Automation, sensing and robotics
Topic: Electret MIC MAX4466 with ADC ADS1015 in python with rasberrypi 3
Replies: 2
Views: 210

Re: Electret MIC MAX4466 with ADC ADS1015 in python with rasberrypi 3

It depends, of course, on how you've got everything wired, but ... The mic doesn't give out negative voltages, it gives out a signal centred on VCC/2, so if you're powering it from 3v3 you'll get values between 0v and 3v3. If the ADC is set to differential mode, it can give negative values, by compa...
by Burngate
Fri Jul 19, 2019 9:59 am
Forum: Automation, sensing and robotics
Topic: Project Idea getting feedback before I begin
Replies: 9
Views: 454

Re: Project Idea getting feedback before I begin

... I often have complaints of it not being answered or not answered within the 10 minutes we are supposed to answer it. ... Am I to understand you to be the member of nursing staff who would be answering, or are you more responsible for the call system itself? If the former, it may be worthwhile t...
by Burngate
Fri Jul 19, 2019 8:37 am
Forum: General discussion
Topic: Power Supply - Type C of Pi 4 model B
Replies: 32
Views: 1903

Re: Power Supply - Type C of Pi 4 model B

Imperf3kt wrote:
Fri Jul 19, 2019 8:00 am
... - power the Pi via the GPIO header, 5v pin/s and ground, or potentially the PoE header, if it can be leveraged for such use.
The PoE header doesn't carry 5v - it takes power from the ethernet socket and passes it to the PoE HAT, which then powers the Pi through the GPIO header.
by Burngate
Thu Jul 18, 2019 5:30 pm
Forum: General discussion
Topic: Raspberry Pi Zero W Power Abbilities
Replies: 5
Views: 456

Re: Raspberry Pi Zero W Power Abbilities

Read somewhere that an LED button can draw 25mA, and with 20 buttons that's 500mA. Plus the 150mA from the Pi I should be good to go. Thanks for the help. The current through an LED depends on how bright you want it, what colour it is (red ones have lower forward voltage than green ones, blue are h...
by Burngate
Tue Jul 16, 2019 9:33 am
Forum: General discussion
Topic: Pi 4 PCB Defect? (fiberglass thread loose)
Replies: 15
Views: 1333

Re: Pi 4 PCB Defect? (fiberglass thread loose)

From the description of what it actually is, I suspect a light touch with a fine file would clean it up nicely. I second this. ... Use of a mask is advised. The dust from the resin probably won't be a problem, but glass fibre dust isn't nice - it can get deep into the lungs and cause problems. Mayb...
by Burngate
Tue Jul 16, 2019 8:58 am
Forum: Graphics, sound and multimedia
Topic: How to send a sound signal through gpio pin to speaker?
Replies: 7
Views: 455

Re: How to send a sound signal through gpio pin to speaker?

I have a rpi 3 model b. ... cuz I’ve already got some stuff lying around. If building it from those isn’t recommended, what about a chip like the lm386? To a certain extent, it depends on how deep you want to go - do you want to buy a car, use some sheet steel and wheels and an engine you happen to...
by Burngate
Thu Jul 11, 2019 6:12 pm
Forum: Beginners
Topic: Voltage Sensors with Raspberry Pi
Replies: 2
Views: 128

Re: Voltage Sensors with Raspberry Pi

What is a "25V Voltage Detector Module 3-Terminal Sensor"?

And what sort of "generator"?
by Burngate
Thu Jul 11, 2019 5:47 pm
Forum: Advanced users
Topic: ESD protection diodes on the BCM2711
Replies: 8
Views: 439

Re: ESD protection diodes on the BCM2711

BlastFX wrote:
Thu Jul 11, 2019 3:44 pm
Guess I'll squeeze a proper level shifter in somehow.
A couple of resistors as a voltage divider should work on an input to the Pi, or a FET appropriately wired will work in both directions.

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