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by tenochtitlanuk
Sun Feb 28, 2016 9:47 pm
Forum: Other programming languages
Topic: FUZE BASIC is now on Rosetta Code
Replies: 55
Views: 9246

Re: FUZE BASIC is now on Rosetta Code

I belong to the minimalist school too- comes of doing my first coding on a 256 byte machine! re Rosetta Code- I'd recommend it to any budding coder. I've added quite a few solutions in another language... it gives you a challenge, and supplies so many other language solutions to adapt that as a by-p...
by tenochtitlanuk
Mon Dec 28, 2015 12:29 am
Forum: Troubleshooting
Topic: RPi V2 Will Not Reboot - need help!
Replies: 10
Views: 1772

Re: RPi V2 Will Not Reboot - need help!

Just a thought- your OP ( original post) says you used sudo dd if=/dev/disk4 of=~/SDCARDBU.dmg I'd have expected the command to have 'bs=4M' within it, and images are usually named ending in '.img' and not ',dmg'. A moment later you are using- sudo dd if=~/SDCARDBU of=/dev/disk4 which I'd expect to ...
by tenochtitlanuk
Mon Dec 14, 2015 5:24 pm
Forum: Automation, sensing and robotics
Topic: Circuit pictures- or circuit diagrams?
Replies: 10
Views: 3098

Re: Circuit pictures- or circuit diagrams?

The point was not that adding colour to wires was an ideal solution- it just made the error as-published more visible. I (and I suspect quite a few others) simoly can't see where these 'pictures' connections are going to! There are interesting discussions on-line about drawing schematics, eg http://...
by tenochtitlanuk
Mon Dec 14, 2015 2:28 pm
Forum: Automation, sensing and robotics
Topic: Circuit pictures- or circuit diagrams?
Replies: 10
Views: 3098

Circuit pictures- or circuit diagrams?

Am I alone in finding the apparent Pi convention of showing circuits via photos and/or (Fritzing-type) diagrams a real problem? For instance, the latest Linux Voice ( one of my favourites, even so!) had the faulty diagram shown below ( permanent short of signal output to +3.3V) and it is really hard...
by tenochtitlanuk
Tue Oct 13, 2015 8:28 am
Forum: HATs and other add-ons
Topic: Neopixel ws281x no longer works- SOLVED
Replies: 1
Views: 809

Re: Neopixel ws281x no longer works

Got it working again. I seem to have gathered a collection of incompatible versions of the library- not helped by adafruit apparently wanting a login/password to download their version.
by tenochtitlanuk
Sun Oct 11, 2015 12:39 pm
Forum: HATs and other add-ons
Topic: Neopixel ws281x no longer works- SOLVED
Replies: 1
Views: 809

Neopixel ws281x no longer works- SOLVED

Both my Pis now give errors when I try to use this library. The neopixel library fails to initialise ( nothing to do with the hardware) My up-to-date Wheezy cards don't work, nor my up-to-date Jessie. I tried an old SD card version last night & it gave no errors. I ( perhaps rashly) then updated it....
by tenochtitlanuk
Sat Jul 11, 2015 7:20 pm
Forum: Automation, sensing and robotics
Topic: OCR optical character recognition of seven segment displays
Replies: 17
Views: 24316

Re: OCR optical character recognition of seven segment displ

I'm still away from any Pi to try. Google 'Raspberry Pi serial port' for lots of possible help. Try http://elinux.org/RPi_Serial_Connection . I wonder if the port is the one whose name you are using or some other name?? I think you may have to be a member of the dialout group- I get lost here too! B...
by tenochtitlanuk
Fri Jul 10, 2015 9:38 pm
Forum: Automation, sensing and robotics
Topic: OCR optical character recognition of seven segment displays
Replies: 17
Views: 24316

Re: OCR optical character recognition of seven segment displ

You might look at http://blog.miguelgrinberg.com/post/a-c ... spberry-pi for some help too..
by tenochtitlanuk
Fri Jul 10, 2015 9:19 pm
Forum: Automation, sensing and robotics
Topic: OCR optical character recognition of seven segment displays
Replies: 17
Views: 24316

Re: OCR optical character recognition of seven segment displ

For 4 digits try ssocr -d 4 Usage: ssocr [OPTION]... [COMMAND]... IMAGE Options: -d, --number-digits=# number of digits in image (-1 for auto) To send to a device/file I'd expect to 'pipe' it to whatever the Bluetooth device is seen as by Linux----- eg ssocr -d 4 > /dev/ttyUSB1 or ssocr d 4 > /dev/t...
by tenochtitlanuk
Wed May 13, 2015 8:58 pm
Forum: General discussion
Topic: Water-flow control
Replies: 6
Views: 3467

Re: Water-flow control

Flexible silicone tubing 'squashed' by a motor would be very easy to set up, since you have a liquid supply 'at pressure'. (the basic technology is used in medical/fish tank peristaltic pumps to deliver accurate doses or flow rates with the liquid not necessarily under pressure) http://www.diga.me.u...
by tenochtitlanuk
Sun Mar 01, 2015 9:41 pm
Forum: Automation, sensing and robotics
Topic: Triac switching mains LED lamps- interesting problem
Replies: 8
Views: 2454

Re: Triac switching mains LED lamps- interesting problem

Mains LEDs use a high-voltage-rated capacitor as a reactance to limit the current, then a full-wave diode bridge. This will of course involve a phase shift of the load current, but no surges. And, as I said, it is not the power triac that suffers!
by tenochtitlanuk
Sun Mar 01, 2015 8:09 pm
Forum: Automation, sensing and robotics
Topic: Triac switching mains LED lamps- interesting problem
Replies: 8
Views: 2454

Re: Triac switching mains LED lamps- interesting problem

No- it is not a surge load current problem. The output triac is undamaged.
It's the low-current one- or the series resistor- which burn out.
by tenochtitlanuk
Sun Mar 01, 2015 7:36 pm
Forum: Automation, sensing and robotics
Topic: Triac switching mains LED lamps- interesting problem
Replies: 8
Views: 2454

Triac switching mains LED lamps- interesting problem

In a current project, IOT fashion, I set some mains lamps to be controlled across the 'net via a web page. Software & Pi are fine. Circuit I use- opto-zerocross-triac triggering a power triac- I've used for years on loads of say 200W plus. Now when used on a 5W mains LED the circuit keeps either blo...
by tenochtitlanuk
Wed Feb 25, 2015 2:51 pm
Forum: Troubleshooting
Topic: Very high shock in raspberry PI 2 Model B
Replies: 7
Views: 2021

Re: Very high shock in raspberry PI 2 Model B

My experience with USB power supplies is that they 'float', ie resistive & capacitive leakage means that their 'stable 5V' may be oscillating on top of tens of volts or more at 50Hz relative to house mains ground.. Luckily the source impedance of this ripple is high. But I've lit a high-brightness L...
by tenochtitlanuk
Wed Feb 18, 2015 6:39 pm
Forum: Troubleshooting
Topic: A Tale of Woe
Replies: 10
Views: 1400

Re: A Tale of Woe

You seem to be trying the sensible things- but I'm surprised by how seldom people with problems don't show their location. That might well encourage someone seeing your OP to PM you and arrange to see you and the Pis and help- or suggest a local Pi group. Hardware & software help is easier in a real...
by tenochtitlanuk
Thu Feb 05, 2015 10:54 pm
Forum: Beginners
Topic: Gradiometer for archaeology
Replies: 21
Views: 5800

Re: Gradiometer for archaeology

Easy <<Speake & Co. also makes a chip called the SCL007 gradiometer. It accepts the inputs from two fluxgate sensors and does the digital mixing for us. The output of the gradiometer chip is an 8-bit parallel word which corresponds to the mix frequency. A zero output means the sensors see the same f...
by tenochtitlanuk
Wed Feb 04, 2015 9:42 pm
Forum: Beginners
Topic: Gradiometer for archaeology
Replies: 21
Views: 5800

Re: Gradiometer for archaeology

I nearly made up one of these when they were described in Wireless World in the 90s. Now I'm tempted to try with one of my Pis.
Come back on this thread if you get anywhere- looks like easy-to-read parallel data.
by tenochtitlanuk
Wed Jan 28, 2015 2:19 pm
Forum: Beginners
Topic: Using Raspberry Pi to output to a simple display
Replies: 16
Views: 2460

Re: Using Raspberry Pi to output to a simple display

For a very simple beginning stick a weighted pendulum bob on a low-friction rotary potentiometer. There's a simple way to read R value using just a capacitor, the Pi and a little Python.
For this being used with an LDR as the varying resistor, see http://diga.me.uk/PiADC.html
by tenochtitlanuk
Wed Jan 28, 2015 2:03 pm
Forum: Troubleshooting
Topic: Voltmeter, Lights Trigger Unwanted GPIO Pin State Change
Replies: 6
Views: 966

Re: Voltmeter, Lights Trigger Unwanted GPIO Pin State Change

I've a similar situation. Using a GPIO to control mains lighting, via opto-coupled SSR/triac. I get occasional transients like you do. I also at one point had my software controlling one GPIO while I'd connected the SSR to a different one by mistake, and the 'wrong' pin also was changing state. But ...
by tenochtitlanuk
Thu Jan 22, 2015 11:57 am
Forum: Beginners
Topic: 10 Electromagnetic locks on 1 Raspberry
Replies: 3
Views: 2342

Re: 10 Electromagnetic locks on 1 Raspberry

I'd use locks like these on Adafruit, which also has help on driver circuits. http://www.adafruit.com/products/1512 There are other electromagnetic locks that need continuous power to the coil, and hold the door shut by magnetic attraction. Power hungry! Avoid. I use photo-isolation and triacs for p...
by tenochtitlanuk
Mon Dec 08, 2014 10:41 pm
Forum: Beginners
Topic: Mirror an sd card
Replies: 2
Views: 644

Re: Mirror an sd card

ie in Google's search box, enter...
sd backup Pi site:http://www.raspberrypi.org
....or something similar.

This finds references to sd card Pi within the named site better than the forum search can!
by tenochtitlanuk
Sun Nov 02, 2014 12:47 pm
Forum: Automation, sensing and robotics
Topic: Make Other Device's LED an input
Replies: 11
Views: 2669

Re: Make Other Device's LED an input

I think you meant INvasive!!
And a phototransistor might be easier than an LDR- I have lots in my parts box, new or from old floppy drives, etc.
by tenochtitlanuk
Sun Oct 26, 2014 11:58 am
Forum: Beginners
Topic: Time lapse project
Replies: 2
Views: 506

Re: Time lapse project

A good introduction to this kind of thing is the RaspPi website http://www.raspberrypi.org/learning/pyt ... era-setup/
by tenochtitlanuk
Thu Oct 23, 2014 7:59 am
Forum: Automation, sensing and robotics
Topic: Turn table Laser Scanner
Replies: 16
Views: 8173

Re: Turn table Laser Scanner

I always felt this would be an application that would be beyond me. Now you've put this up & made me believe I too could do it. MANY thanks!
by tenochtitlanuk
Wed Oct 15, 2014 9:46 pm
Forum: Other projects
Topic: The doppler effect
Replies: 1
Views: 654

Re: The doppler effect

As other viewers of that video commented, the demo simply shows amplitude modulation of a light beam and NO Doppler effect is involved. Simplest Doppler display with a Pi? Connect a loudspeaker on a metre-long, strong cord; use Pi to generate a sine wave; swing speaker round your head. YOU will hear...

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