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by Burngate
Thu Jul 02, 2020 10:12 am
Forum: Beginners
Topic: Yet another question about LEDs and resistors...
Replies: 7
Views: 357

Re: Yet another question about LEDs and resistors...

Ok, found the source of your screenshot https://www.ledsupply.com/leds/5mm-led-orange-610nm-30nm-degree-viewing-angle And I have a screenshot you may find interesting - it's from a Kingbright green LED datasheet, but the basics should apply to most LEDs. L-934GD.png As you can see, although it's spe...
by Burngate
Thu Jul 02, 2020 9:26 am
Forum: Off topic discussion
Topic: Biomimicry in PCB Design
Replies: 6
Views: 894

Re: Biomimicry in PCB Design

... naturally designed to maximize the space inside of it by increasing surface area (has lots of folds going back and forth) That confuses me - doesn't the folding, at least of the endoplasic reticulum - minimise the space taken up? But I'm not convinced that somewhat random folding of a circuit b...
by Burngate
Tue Jun 30, 2020 9:44 am
Forum: Beginners
Topic: Electronics questions
Replies: 7
Views: 530

Re: Electronics questions

I was thinking to switch the MCP3008 to 5V ... Don't. If you use 5v, the output from it to the Pi will approach that, and the Pi will be damaged. ... so it will sample at 200ksps. The maximum frequency of the signal must be 100KHz, how can I be sure that I won't wiggle the potentiometer too fast? W...
by Burngate
Mon Jun 29, 2020 6:22 pm
Forum: General discussion
Topic: No red LED Pi 4B
Replies: 9
Views: 516

Re: No red LED Pi 4B

You have, naturally, probed with your meter round that LED, haven't you? Bottom end is GND, obviously. If the LED is open circuit, you should see 4.somethingV at its anode. If R17 is broken, you should see 0V, and the same if it's being held off by Q1 In the latter case, Q1's gate should be high unl...
by Burngate
Mon Jun 29, 2020 10:45 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Pi4 3.5mm audio out cuts off at 19kHz
Replies: 7
Views: 580

Re: Pi4 3.5mm audio out cuts off at 19kHz

The low-pass filter shown there gives 6dB/octave with a 3dB turnover at 145kHz. Not what's shown on his graph, which has a 3dB turnover at 19kHz and thereafter something in excess of 18dB/octave. What frequency does the Pi's PWM work at? What does the Pi do to the audio before it feeds into the PWM?...
by Burngate
Sat Jun 27, 2020 5:50 pm
Forum: Off topic discussion
Topic: Wish list for the foundation
Replies: 53
Views: 5945

Re: Wish list for the foundation

Just a minor gripe of mine. The idea that everybody should re-invent every wheel, is, well, just not in keeping with the modern world. One of those things that everyone says, without thought. If inventing wheels were easy, it wouldn't have needed the Egyptians to do it - Neanderthal Man would have h...
by Burngate
Sat Jun 27, 2020 11:00 am
Forum: Troubleshooting
Topic: I removed the back feed, still won't boot if USB HDD is attached.
Replies: 14
Views: 658

Re: I removed the back feed, still won't boot if USB HDD is attached.

If you don't remove the power feed to the Pi - which you aren't, since you're just trying to reboot - then whether or not the hub back-feeds power to the Pi is irrelevant. It seems more likely that the Pi is waiting for a reply from the drive, and unplugging the hub tells the Pi that the drive is no...
by Burngate
Fri Jun 26, 2020 10:03 am
Forum: Beginners
Topic: Driving SMD5050 LED strip using IRLZ34N
Replies: 5
Views: 338

Re: Driving SMD5050 LED strip using IRLZ34N

I think your best bet would be what's sold as a logic level converter. They're generally meant to translate 3v3 signals to 5v, but would work just as well translating to 12v And the advantage for is you can get them as four on one board - one for each colour and one spare! 3-12v.png Just read 12v in...
by Burngate
Fri Jun 26, 2020 9:31 am
Forum: General discussion
Topic: Raspberry Pi integrated storage
Replies: 59
Views: 2722

Re: Raspberry Pi integrated storage

Given what a Pi is meant to be - not bank-breaking if you break it - keeping the OS on a separate, cheap, disposable SD card is a far, far better thing than anyone else has ever bothered doing, at least according to Charlie Boy.
by Burngate
Thu Jun 25, 2020 10:04 am
Forum: Beginners
Topic: Remove the wireless card
Replies: 24
Views: 1699

Re: Remove the wireless card

It strikes me as weird that the 3B / 3B+ / 4B have both WiFi and PoE, while the 2B has neither. With the 4B, If you use PoE, WiFi is redundant; WiFi implies no cable so you'll have to provide power some other way. With the 2B, either option needs desk-clutter. That's without considering the down-sid...
by Burngate
Thu Jun 25, 2020 9:17 am
Forum: Beginners
Topic: Driving SMD5050 LED strip using IRLZ34N
Replies: 5
Views: 338

Re: Driving SMD5050 LED strip using IRLZ34N

Hi, may I suggest you're using a logic level FET, but driving it from 3.3 not 5. The IRLZ34N is a FET, it's a 3.3v max gate voltage MOSFET Not quite true. Its max gate voltage is 16v - it'll survive if you give it that much - but its gate threshold voltage is typically between 1v and 2v. That means...
by Burngate
Sat Jun 20, 2020 5:26 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: SRF08 power
Replies: 8
Views: 439

Re: SRF08 power

Just make sure you don't add pull-up resistors to 5v on the SDA & SCL lines.
The Pi already has pull-up resistors to 3v3, so no more are needed anywhere.
by Burngate
Sat Jun 20, 2020 10:10 am
Forum: Off topic discussion
Topic: Animal question
Replies: 21
Views: 2363

Re: Animal question

If the Raspberry Pi were an animal, ... Why are we limited to the Animal Kingdom? There're far more interesting things elsewhere! There's the bacteria, of course, and viruses, but they're not really very interesting unless you catch one. We could ignore the Plant Kingdom - sitting there doing not v...
by Burngate
Sat Jun 20, 2020 8:20 am
Forum: Graphics, sound and multimedia
Topic: Outdoor audio and high wattage speakers
Replies: 15
Views: 4192

Re: Outdoor audio and high wattage speakers

The difference between 60w and 100w is generally undetectable to the average human. You need 4x or 10x to make a difference. People in general are piss poor at judging output power. 60W to 100W is less than 3dB. The human ear can't usually detect less than 6dB Back before Covid-19, you went to see ...
by Burngate
Fri Jun 19, 2020 10:22 am
Forum: Troubleshooting
Topic: I think my Pi3 is almost dead
Replies: 7
Views: 427

Re: I think my Pi3 is almost dead

Hmph. Need more coffee
by Burngate
Fri Jun 19, 2020 9:23 am
Forum: Troubleshooting
Topic: I think my Pi3 is almost dead
Replies: 7
Views: 427

Re: I think my Pi3 is almost dead

GPIO pin 1 and 2: ~5.1V and ~3V3 respectively. PP1: 5V, same as input. PP10: ~1.8V (is acting as a browndown detector?) I guess there's a problem here. PP21: Should be high at 3V3 but I got ~0V PP25: ~0V when it should be 5V on the USB bus. (I'm assuming this is a 3B, not 3B+ or other variant) PP1 ...
by Burngate
Thu Jun 18, 2020 9:32 am
Forum: Beginners
Topic: Raspberry Pi OS Imager does not find SD card
Replies: 12
Views: 665

Re: Raspberry Pi OS Imager does not find SD card

Could it be that both the tower's slot and the USB card reader aren't SDXC compatible? They can read but not write?
by Burngate
Thu Jun 18, 2020 9:25 am
Forum: General discussion
Topic: Pi Zero bulk inquiry
Replies: 31
Views: 1668

Re: Pi Zero bulk inquiry

Zeros on the whole are in short supply at the moment anyway, heavy demand from the medical sector, so most are going that way. I find that interesting. In general, the medical profession tend to be quite obsessive about the safety and reliability of their equipment - rather more than we tinkerers, ...
by Burngate
Wed Jun 17, 2020 9:36 am
Forum: General discussion
Topic: Question about Raspberry Pi 4 LED design
Replies: 23
Views: 1215

Re: Question about Raspberry Pi 4 LED design

... I would have done it totally different: I'd have only the green LED(s) light up when the Pi is up and running ... I'd have the red LED glow, once the Pi is in the "shutdown" state. Interesting, isn't it? If the designers had wanted to indicate "it's shut down properly, so you can safely remove ...
by Burngate
Mon Jun 15, 2020 9:36 am
Forum: Beginners
Topic: Use of GPIO pins
Replies: 10
Views: 403

Re: Use of GPIO pins

The GPIO pins I'm using are alle the green one's as mentioned here: https://www.raspberrypi-spy.co.uk/2012/06/simple-guide-to-the-rpi-gpio-header-and-pins/#prettyPhoto/1/ Those colours aren't on a physical RPi3B. Do we really need to argue about where the colour is? It seems obvious to me that edsu...
by Burngate
Mon Jun 15, 2020 9:03 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: ADC I2C for slider potentiometer
Replies: 7
Views: 397

Re: ADC I2C for slider potentiometer

Just my opinion - you may ignore me if you wish, but ... SPI is said to be better for high-speed applications, but how fast can you realistically waggle those potentiometers? I doubt you will notice any delay shorter than 50ms or so. Using those I2C Hobbytronics devices and giving each a different a...
by Burngate
Mon Jun 15, 2020 8:28 am
Forum: Troubleshooting
Topic: Composite Bad Display
Replies: 5
Views: 324

Re: Composite Bad Display

hippy wrote:
Sun Jun 14, 2020 1:11 pm
Are you sure you have your white composite wire connected to the correct RCA/phono mounting pad ?

I thought the two outer pads were for the shield/0V connection, the centre pad the video feed.
Surprisingly not.
DSC_0018-1.jpg
DSC_0018-1.jpg (58.21 KiB) Viewed 237 times
by Burngate
Wed Jun 10, 2020 5:53 pm
Forum: Beginners
Topic: Building a digital clock including 3 digit milliseconds
Replies: 7
Views: 414

Re: Building a digital clock including 3 digit milliseconds

You've got 9 digits, each with 7 segments - that's 63 segments. How are you going to drive them? Most clocks I've come across multiplex them so that in reality only one digit is lit at any one time; your eyes integrate them into something sensible. A camera would see something less interesting, and ...
by Burngate
Mon Jun 08, 2020 6:09 pm
Forum: General discussion
Topic: Question to Raspberry Pi Foundation
Replies: 44
Views: 2465

Re: Question to Raspberry Pi Foundation

It is perhaps a reminder that, unlike many of us old timers here, there are many people in the world who have never handled any kind of electronics. They have never been taught such things in school. They have never built the simplest circuit in any science class as we did back in the day. They hav...

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