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by davidcoton
Mon May 20, 2019 9:30 pm
Forum: Beginners
Topic: Small part fell off my pi
Replies: 11
Views: 328

Re: Small part fell off my pi

Yes, it carries the left audio signal to the A/V jack. See my link just a couple of posts ago. You could either replace the capacitor or just short the connection with some wire.without it, the Pi will still function 100% normal (except you'll get no L channel audio over the A/V jack.) Do NOT short...
by davidcoton
Mon May 20, 2019 8:20 am
Forum: Beginners
Topic: Down convert +24DC to 5V
Replies: 5
Views: 120

Re: Down convert +24DC to 5V

scotty101 wrote:
Mon May 20, 2019 6:50 am
dl324 wrote:
Mon May 20, 2019 12:36 am
You'd fry your Pi.
Wrong answer. Nothing would happen because there wouldn't be a complete circuit.
Depends what else is connected and how. I wouldn't rely on "Nothing", but "fry" is not certain.
scotty101 wrote:
Mon May 20, 2019 6:50 am
In this case the COM pin should be used as ground
+1
by davidcoton
Sun May 19, 2019 3:26 pm
Forum: General discussion
Topic: Atmega328p + RPI : ICSP programming providing 3.3V
Replies: 6
Views: 113

Re: Atmega328p + RPI : ICSP programming providing 3.3V

I would not recommend applying external 3V3 to the Pi GPIO header pin 3V3 under any circumstances, whether ther Pi is powered or not. The pin is designed for providing a 3V3 source; using it as a sink could damage the Pi, probably permanently and completely. The Pi 3B+ (and 3A+?) is particularly sen...
by davidcoton
Sun May 19, 2019 3:16 pm
Forum: General discussion
Topic: memory problem?
Replies: 15
Views: 310

Re: memory problem?

ankith26 wrote:
Sun May 19, 2019 2:27 pm
Have a look herehttps://www.raspberrypi.org/forums/view ... hp?t=46472
That's the link you need
by davidcoton
Sat May 18, 2019 8:45 am
Forum: General discussion
Topic: Danger of high voltage from HDMI cable
Replies: 11
Views: 426

Re: Danger of high voltage from HDMI cable

The USB charger I'm using gives a negative which is 100 VAC relative to earth. When the live and neutral were the wrong way around this value was about 55 VAC. Could the USB charger have been damaged by the live and neutral reversal? Eventually my Pi will be powered by a PC PSU (which will be power...
by davidcoton
Fri May 17, 2019 11:15 pm
Forum: General discussion
Topic: RPI and CE and FCC compliance: external board
Replies: 10
Views: 233

Re: RPI and CE and FCC compliance: external board

(... I don’t know why some people got stressed' :-( ) It's not stress. It's just that no-one wants to see you get into legal problems by following advice from people here, who are either not lawyers or who won't admit to being lawyers. To cover yourself, you need paid legal advice from someone qual...
by davidcoton
Fri May 17, 2019 3:10 pm
Forum: Troubleshooting
Topic: Why Raspberry pi is storing different number of samples different second?
Replies: 13
Views: 194

Re: Why Raspberry pi is storing different number of samples different second?

Is there any way that I can have fixed number of samples per second with high precision in case the sampling rate is as high as 100 or 150? Here's two to start with: Record the time before the processing starts. When you get to the sleep, calculate the remaining time to the next sample time and use...
by davidcoton
Thu May 16, 2019 8:45 am
Forum: General discussion
Topic: Danger of high voltage from HDMI cable
Replies: 11
Views: 426

Re: Danger of high voltage from HDMI cable

900uA through 910R implies about 820mV across the resistor. That sort of voltage level is not dangerous, nor are currents around 1mA. But the off-load voltage of 240V certainly is dangerous to a Pi, if there is a discharge path that hits something sensitive. As you found it will also give you a ting...
by davidcoton
Wed May 15, 2019 9:44 pm
Forum: Beginners
Topic: Pi Zero USB hub
Replies: 17
Views: 1827

Re: Pi Zero USB hub

Crtek User statistics

Joined:
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Last active:
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You are unlikely to get an answer. If you have an issue, start a new thread and post the details.
by davidcoton
Wed May 15, 2019 3:45 pm
Forum: Off topic discussion
Topic: is the pi worth it?
Replies: 103
Views: 3014

Re: is the pi worth it?

DarkPlatinum wrote:
Wed May 15, 2019 12:41 pm
you can send it to me to look after it with TLC.
Actually, we can't. Your location is "Unknown".
by davidcoton
Tue May 14, 2019 7:39 pm
Forum: Beginners
Topic: Serial communication between camera and Pi
Replies: 2
Views: 72

Re: Serial communication between camera and Pi

The pi UART pins run with 3V3 logic. What voltage does the camera expect? (NB If the camera returns data at 5V levels, this can damage your Pi.)
by davidcoton
Mon May 13, 2019 8:39 pm
Forum: Off topic discussion
Topic: is the pi worth it?
Replies: 103
Views: 3014

Re: is the pi worth it?

jamesh wrote:
Mon May 13, 2019 3:15 pm
* Built in sandwich toaster and pink unicorn, dancing on a rainbow.
I think there is a serious Safety Elf issue here. :shock:
What happens if the unicorn slips on the rainbow (which can get icy), and falls into the toaster while it is hot? :o
by davidcoton
Sun May 12, 2019 11:32 am
Forum: General programming discussion
Topic: A Second Age of Personal Computing
Replies: 38
Views: 962

Re: A Second Age of Personal Computing

Burngate wrote:
Sun May 12, 2019 9:53 am
So we end up with the country run by the PR guys and the ad agencies.
And in what way is that worse than the current situation? :( :shock: :twisted:
by davidcoton
Sat May 11, 2019 10:28 pm
Forum: For sale
Topic: "ETHA Light Switch", an intelligent time switch
Replies: 4
Views: 212

Re: "ETHA Light Switch", an intelligent time switch

I qualified as an electrician a few years ago, it took two weeks of training and two exams, one on Building regs and one on Wiring regs. (Okay that is unusually quick, but most candidates are not degree-qualified electrical engineers :o ) The qualifications do have to be kept up to date, and work is...
by davidcoton
Fri May 10, 2019 3:07 pm
Forum: General discussion
Topic: 5V 2A Phone charger
Replies: 20
Views: 335

Re: 5V 2A Phone charger

H0R4T1U wrote:
Fri May 10, 2019 2:58 pm
what if i would use remote access through ssh would i still need 5v and 2.5A ?
That depends on two things:
  1. What peripherals are connected, and how much power they use
  2. How hard your Pi is working
by davidcoton
Fri May 10, 2019 1:42 pm
Forum: General discussion
Topic: 5V 2A Phone charger
Replies: 20
Views: 335

Re: 5V 2A Phone charger

Try it and see. As long as you don't have too many power hungry peripherals, it might work. The risk is that chargers may be rated with the correct voltage and enough current, but they can't do both at the same time. Watch for the red PoWeR LED going out at startup or under heavy load, watch for the...
by davidcoton
Thu May 09, 2019 9:44 pm
Forum: Off topic discussion
Topic: My last post about IR transceiver seems to have been removed from this forum.
Replies: 15
Views: 527

Re: My last post about IR transceiver seems to have been removed from this forum.

mahjongg wrote:it might be time to read your warnings,
JOOI, how? Where can I find them (or know that there are none)?
Presumably there is no push notification of warnings?
by davidcoton
Thu May 09, 2019 9:36 pm
Forum: Off topic discussion
Topic: Pi gets a mention...
Replies: 17
Views: 600

Re: Pi gets a mention...

There was no teaching of the computing O-levels and A-levels when I was doing my exams between 19 97 & 1981. Sorry Dougie, presumably you failed both History and Maths? :lol: [rant] Apart from that, I have to agree with the general thread sentiment about the treatment of teachers. Some years ago, w...
by davidcoton
Wed May 08, 2019 3:36 pm
Forum: Off topic discussion
Topic: Are humourous signatures allowed on this foum?
Replies: 12
Views: 498

Re: Are humourous signatures allowed on this foum?

It's really hard to speak normally now a days without someone listening in being offended. I have no idea how one would make an acceptable joke. You really shouldn't mention "speak", as it may offend people who do not speak. Here we go: "A person, another person and yet a another person entered an ...
by davidcoton
Wed May 08, 2019 12:19 pm
Forum: General discussion
Topic: RPi for button presser
Replies: 19
Views: 400

Re: RPi for button presser

The diode is shown the wrong way round in the circuit diagram -- it is there to remove the reverse voltage generated when the solenoid is turned off and the magnetic field collapses. The layout in an earlier post shows it the other way round, which is correct. If it is (or, at any time, was) actuall...
by davidcoton
Wed May 08, 2019 11:17 am
Forum: Beginners
Topic: Will a power supply with a higher amp-age work with the pi?
Replies: 22
Views: 14039

Re: Will a power supply with a higher amp-age work with the pi?

A lot of that is incorrect. The size of the reservoir is not the "amperage capability". The current is not the "actual water" but the rate of flow of the water. I respectfully disagree. Some people (involved in teaching electrical theory) have given up on the water analogy. I think it is still usef...
by davidcoton
Wed May 08, 2019 11:04 am
Forum: General discussion
Topic: Where do I get news about the PI?
Replies: 28
Views: 768

Re: Where do I get news about the PI?

rpdom wrote:
Wed May 08, 2019 9:38 am
... because all breakfast cereals have to be "healthy" now, it will have a reduced fat content. It will only boot from FAT12, not FAT16 or FAT32.
:lol: :D
by davidcoton
Wed May 08, 2019 8:52 am
Forum: General discussion
Topic: Where do I get news about the PI?
Replies: 28
Views: 768

Re: Where do I get news about the PI?

ankith26 wrote:
Wed May 08, 2019 3:32 am
I imagine Liquid helium will be soo cool that the cost of the pi can go to an ABSOLUTE ZERO. :D
So -- the Pi0 successor, with the same processor as the Pi4, will be the PiAbsolute0? Or the Pi-273.16C?
And it comes free in every packet of Corn Flakes?
by davidcoton
Wed May 08, 2019 8:47 am
Forum: General discussion
Topic: Fried my pi . Please help me to understand the root cause.
Replies: 34
Views: 999

Re: Fried my pi . Please help me to understand the root cause.

I'm inclined to think that the flashover took more than the normal 5V 2A supply. So probably a lightning-induced voltage on the incoming power lead or sensor wires. That may or may not have been made worse by moisture/water in the case -- there is no direct evidence of it, and lightning can induce e...
by davidcoton
Tue May 07, 2019 8:28 pm
Forum: Troubleshooting
Topic: Raspberry Pi B+ - Help to replace micro SD socket and power LED
Replies: 18
Views: 447

Re: Raspberry Pi B+ - Help to replace micro SD socket and power LED

In the second reply to this thread I pointed out that it was possible to check whether the board is functional without needing access to the microSD card slot. I still think it would be sensible to check that first, before undertaking cosmetic repairs which will be pointless and ineffective if ther...

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