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by Burngate
Mon Dec 11, 2017 11:03 am
Forum: Beginners
Topic: Pi Zero Ripple Voltage
Replies: 1
Views: 45

Re: Pi Zero Ripple Voltage

... Pi Zero 1.3 ... powering it through the GPIO pins. I read that powering the Pi through the GPIO pins means bypassing the regulator No. The Pi has no 5v regulator, and the Pi Zero doesn't even have a fuse between the microUSB sockets and the GPIO header, so powering it through the header pins wo...
by Burngate
Sun Dec 10, 2017 11:01 am
Forum: The MagPi
Topic: Issue 64 of Magpi
Replies: 2
Views: 136

Re: Issue 64 of Magpi

As of 11 o'clock today, https://www.raspberrypi.org/magpi-issues/MagPi64.pdf is working.
by Burngate
Thu Dec 07, 2017 11:46 am
Forum: General discussion
Topic: High Precision AD/DA board ADS1256
Replies: 7
Views: 279

Re: High Precision AD/DA board ADS1256

The first 12 bits represent 1 part in 4k; the next hexadecimal digit takes it to 64k.
So if your input range is 2.5V your input could be changing by (of the order of) 40uV
Unless your reference voltage is changing by that much. Are you sure it isn't?
by Burngate
Wed Dec 06, 2017 6:16 pm
Forum: General discussion
Topic: OK. This is ridiculous!
Replies: 34
Views: 1537

Re: OK. This is ridiculous!

For what it's worth, I've gota couple of comments. First is the Moore's law syndrome and its corollary - not only do things get twice as complicated every two years, but also we expect twice as many bangs for our buck. So what was exciting, wonderful, an early Christmas present, a few years ago now ...
by Burngate
Wed Dec 06, 2017 9:46 am
Forum: Automation, sensing and robotics
Topic: Possible to read potentiometer values from a sensor?
Replies: 14
Views: 472

Re: Possible to read potentiometer values from a sensor?

Bourns 3362P-01.jpg
Bourns 3362P-01.jpg (4.65 KiB) Viewed 111 times
Bourns 3362P-02.jpg
Bourns 3362P-02.jpg (4.46 KiB) Viewed 111 times
Solder the wires to the pins on the under-side of the board.
by Burngate
Tue Dec 05, 2017 6:14 pm
Forum: Beginners
Topic: Safety Instructions
Replies: 18
Views: 593

Re: Safety Instructions

That put me in my place, didn't it! Pass on our congratulations for surviving, if you could, as well as our commiserations for being struck. So maybe I won't shelter under trees any more. Learning from one's own experience isn't necessarily the best option, when someone else's experience is availab...
by Burngate
Tue Dec 05, 2017 5:51 pm
Forum: General discussion
Topic: 3V3 rise time
Replies: 21
Views: 644

Re: 3V3 rise time

Quote from the Diodes Inc pdf: As the input voltage approaches the output voltage, the converter turns the P-Channel transistor continuously on. In this mode the output voltage is equal to the input voltage minus the voltage drop across the P-Channel transistor So the 3v3 rail starts rising as soon ...
by Burngate
Tue Dec 05, 2017 12:05 pm
Forum: Beginners
Topic: Safety Instructions
Replies: 18
Views: 593

Re: Safety Instructions

You're asking "What can go wrong?" Actually, the question should also include "How likely is it?", "What's the cost?" and "What's the cost of not doing it?" We're often told not to stand under a tree in a thunder storm, but I've known lots of people do so, and none of them has died. On the other han...
by Burngate
Mon Dec 04, 2017 6:41 pm
Forum: Beginners
Topic: 1MOhms
Replies: 2
Views: 122

Re: 1MOhms

brouno wrote:
Mon Dec 04, 2017 2:42 pm
... an automated switch
Can you give us more info about this?
by Burngate
Sun Dec 03, 2017 10:06 am
Forum: Beginners
Topic: Command line question
Replies: 7
Views: 299

Re: Command line question

Thankyou for that.
Having been brought up on RiscOs, I've always felt Linux to be a large mountain to climb. I've pottered round the lower slopes, but never felt at home. This looks like it might be the funicular I need.
by Burngate
Sat Dec 02, 2017 6:20 pm
Forum: General discussion
Topic: LM1084 power supply
Replies: 36
Views: 837

Re: LM1084 power supply

Forth ... yes. And Reverse Polish. I had a Sinclair Scientific - I may still have it somewhere ... and I may have bought or just wanted to buy a computer that ran Forth. I'll have to dig through the treasure trove. Somewhere below the VHS machine, and above my Neanderthal forebear's knuckle-bones.
by Burngate
Sat Dec 02, 2017 5:50 pm
Forum: General discussion
Topic: Pi Zero W availability
Replies: 110
Views: 5647

Re: Pi Zero W availability

"affordable enough for any project!" to me is an invitation to buy multiples To me, that doesn't mean you can run multiple projects concurrently - it means you could run your Christmas tree lights, then your Easter Bunny lights, then ... all with the same Zero. I figured the low cost was because it...
by Burngate
Sat Dec 02, 2017 12:03 pm
Forum: Troubleshooting
Topic: GPIO not going all the way LOW [solved]
Replies: 17
Views: 548

Re: GPIO not going all the way LOW

gordon77 wrote:
Sat Dec 02, 2017 11:10 am
I am confused
You and me, both.
Looking further at that image, almost nothing seems to go where I would have expected.
We'd all get along better if we could see a proper circuit diagram, rather than a board layout, and more than just the bit we're allowed to see.
by Burngate
Fri Dec 01, 2017 7:17 pm
Forum: General discussion
Topic: LM1084 power supply
Replies: 36
Views: 837

Re: LM1084 power supply

In my yearly report, my form master wrote "Andrew is trying. Very trying" He didn't really, but I'm sure he would have liked to. RMS: Root of the Mean of the Squares SAR: Square then Average then Root It depends what order you think in. Imagine a cookery book saying "Serve on plates the result of co...
by Burngate
Fri Dec 01, 2017 7:08 pm
Forum: Troubleshooting
Topic: GPIO not going all the way LOW [solved]
Replies: 17
Views: 548

Re: GPIO not going all the way LOW

Looking at the data sheet, I note there's a couple of packages, with different pin-outs. It looks like you've got the PWR package. Pins.png Your layout appears to send GPIO pin 16 to pin 2 of the chip, which is correct for the DQS package, but not for the PW package. Could that be your problem? Also...
by Burngate
Fri Dec 01, 2017 6:51 pm
Forum: Off topic discussion
Topic: Official Raspberry Pi PSU changeable heads
Replies: 5
Views: 428

Re: Official Raspberry Pi PSU changeable heads

That's because, although the council is obliged to collect stuff to be recycled, it also has to save money, and land-filling stuff is cheaper than recycling. Roll on the day when we run out of places to bury rubbish. When I was a school-kid, there was an area of marsh near Bidston Hill which I hated...
by Burngate
Fri Dec 01, 2017 6:36 pm
Forum: General discussion
Topic: LM1084 power supply
Replies: 36
Views: 837

Re: LM1084 power supply

The factor of √2 only works for sine-waves. A square wave, for example, doesn't need it because the original squaring gives a straight line so its average is just the original value, and square-rooting gets you back to where you started. If you start with a PWM signal things get more complicated, de...
by Burngate
Fri Dec 01, 2017 6:08 pm
Forum: Recommended peripherals
Topic: Current specifications
Replies: 2
Views: 155

Re: Current specifications

There's a document written by The Guy Who Knows, https://www.scribd.com/doc/101830961/GPIO-Pads-Control2 , that says it all. If you wish the GPIO to give the guaranteed voltages - 0.8v for low, 1.3v for high - then don't take more current than specified. You can set a GPIO to give any value upto 16m...
by Burngate
Thu Nov 30, 2017 6:46 pm
Forum: Advanced users
Topic: powering zero by usb wall outlet
Replies: 9
Views: 324

Re: powering zero by usb wall outlet

Given that Pis are generally rather more picky about their supply than a phone would be, I would be wanting to know more about what's behind the face-plate. But it shouldn't be too much of a problem, since as I understand it, the wall outlet should not be mounted in a flammable wall material. Though...
by Burngate
Thu Nov 30, 2017 6:27 pm
Forum: General discussion
Topic: LM1084 power supply
Replies: 36
Views: 837

Re: LM1084 power supply

A full wave rectified AC will produce an output √2 times the RMS voltage. The missing link. That is the piece I needed. I would never have guessed √2 * v . That did give me the a value near the 37 volts I measured. I don't know whether you should blame the engineers who invented the acronym "RMS", ...
by Burngate
Thu Nov 30, 2017 6:01 pm
Forum: Troubleshooting
Topic: GPIO not going all the way LOW [solved]
Replies: 17
Views: 548

Re: GPIO not going all the way LOW

... connected to a voltage translator ... (image) You can see where GPIO16 goes straight into the voltage translator. It's a fairly standard TI Bidirectional voltage translator commonly used on motor capes. Can you provide any information regarding this chip? It's difficult enough trying to deciphe...
by Burngate
Wed Nov 29, 2017 9:33 am
Forum: Troubleshooting
Topic: RPi 3 boots and runs fine but red power led won't light
Replies: 8
Views: 259

Re: RPi 3 boots and runs fine but red power led won't light

You seem to have found the problem! My original thought, that the circuit is too simple to be problematical, is obviously too simplistic. Physical damage didn't occur to me. I haven't put my Pis in cases for a couple of reasons - one: I'm too cheapskate to buy a case, and two: they'd never stay in i...
by Burngate
Tue Nov 28, 2017 12:21 pm
Forum: Troubleshooting
Topic: RPi 3 boots and runs fine but red power led won't light
Replies: 8
Views: 259

Re: RPi 3 boots and runs fine but red power led won't light

The circuit driving the red power LED on the B+, 2B and 3B (there's no 2B+) is quite simple - a APX803-46SAG chip to detect the 5v rail voltage, fet, led and a few resistors. One dying could be called unfortunate; more than one invites suspicion. Does the screen show the lightning bolt symbol? One p...
by Burngate
Tue Nov 28, 2017 11:12 am
Forum: General discussion
Topic: LM1084 power supply
Replies: 36
Views: 837

Re: LM1084 power supply

... this "Swan" fellow... https://en.wikipedia.org/wiki/Joseph_Swan Both he and Edison were into stage lighting. They both took out patents (1879), but Swan got there first. They both used carbon filaments, with tungsten not being used until the 1920s https://en.wikipedia.org/wiki/Incandescent_ligh...
by Burngate
Tue Nov 28, 2017 10:48 am
Forum: Recommended peripherals
Topic: Adafruit speaker bonnet troubleshoot
Replies: 3
Views: 205

Re: Adafruit speaker bonnet troubleshoot

2.5A should be enough; the amplifiers on the bonnet only take about 5mA when not doing anything, so shouldn't shut everything down. At worst, if it was on edge, I would expect that extra load to turn the red LED off but otherwise not do too much. Certainly not totally shut the Pi down. So you would ...

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