Category Archives: Stuff

MacOSX Remove Timemachine Backups.backupdb folder

If you ever decide to change which drive your MacOSX Time machine backups are stored on, you may find that you will need to remove the “Backups.backupdb” folder from the old drive after you have performed the switchover.

Whilst you can do this in the conventional manner by right-clicking and selecting “Move to Trash”, you will soon discover that it is a very slow process. If you are confident with the command line you can perform the same action from the command line, using the “Terminal” application. I will reiterate that if you are not comfortable using the Terminal then this article may not be for you – a lot of damage can be caused by using the terminal incorrectly.

In order to achieve this you need to know where your Backups.backupdb folder is. With my setup the old folder is stored on an external drive called “LaCie1000”.

Using the Terminal

1. Go to the spotlight tool on your mac (the Magnifying glass icon) and start typing Terminal.

2. You should see a black icon and the application “Terminal” – click on this to launch the application.

3. If you do not know what your drive is called you can run this command:

Listing MacOSX Drive volumes in the command line

diskutil list

4. If you try and remove the folders using the normal “rm” command you might be presented with thousands of “Operation not permitted” errors. To get around this we can prefix our command using a “bypass” helper which will stop this error from occurring and thus successfully removing the folder. Apple, for whatever reason have changed the location of this helper so take note of the paths below, and choose the correct one for your operating system version.

In 10.8 Mountain Lion, bypass moved into ‘Helpers’:

/System/Library/Extensions/TMSafetyNet.kext/Helpers/bypass

In 10.10 Yosemite, bypass moved here:

/System/Library/Extensions/TMSafetyNet.kext/Contents/Helpers/bypass

Running the command

5. As I use OSX Yosemite the latter path is the one for me, and this will make my final command as follows:

sudo /System/Library/Extensions/TMSafetyNet.kext/Contents/MacOS/bypass rm -rfv /Volumes/[your disk]/Backups.backupdb/[path]

If you run the above you should start seeing a long list of files being removed.

It is important to note that this process is still not instant, but is far quicker in my opinion than the “Move to trash” method.

Good luck.

 

Tilley lamp cleanup

I was clearing out some junk in the garage today and came across an old Tilley lamp, covered in cobwebs and dirt it was. So when I got it back home I dismantled the lamp to take the glass bowl out and gave it a good wash in soapy water.

before_glass

After brushing all the dirt of the lamp body I just used a bit of metal polish wadding. I wanted to retain a fairly worn look so there was no attempt to make it look like a new lamp. I’m quite pleased with the results and now have it hanging outside my log cabin door. Very nice!

finished

How to build an electronic timelapse auto panner – part 2

In Part 1, we looked at the basic requirements for my autopanner. Today’s article will explore the motor control in more detail, which is the real core of the project.

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Stepper Motor 101

If you’ve ever connected a dc motor up to a 9v battery with a positive and negative wire you will have noticed that the motor will start to spin. If you were to do the same with a stepper motor it would probably do nothing. Why is this? Well stepper motors are a little more complicated than the stanrd motor and often require a separate controller board to drive them. Sometimes the controller is embedded if the motor is large enough to contain it. The controller essentially contains a microprocessor, some power inputs and some control inputs and outputs.

The Stepper Motor is controlled by a series of electromagnetic coils. The center shaft has a series of magnets mounted on it, and the coils surrounding the shaft are alternately given current or not, creating magnetic fields which repel or attract the magnets on the shaft, causing the motor to rotate.This  allows for very precise control of the motor. Just to confuse matters there are unipolar steppers and bipolar steppers – more on the differences later!

The motor I chose to use is one which I had included with my Arduino kit. Its a “28YBT-48 DC 5V Stepper Motor with ULN2003 Driver/Controller”stepper2

 

The datasheet for this motor is as follows:

  • Rated voltage: 5VDC
  • Number of Phases: 4
  • Speed Variation Ratio: 1/64
  • Stride Angle: 5.625° /64
  • Frequency: 100Hz
  • DC resistance: 50Ω±7%(25℃)
  • Idle In-traction Frequency > 600Hz
  • Idle Out-traction Frequency > 1000Hz
  • In-traction Torque >34.3mN.m(120Hz)
  • Self-positioning Torque >34.3mN.m
  • Friction torque 600-1200 gf.cm
  • Pull in torque 300 gf.cm
  • Insulation grade Ac

Here is a closeup of the controller and a pin-out diagram:

controller

pinouts

So the next step is to be able to instruct the controller how to work. For this I will be using a standard Arduino Uno board. In a later tutorial I will attempt to swap this for an Adruino mini board which will fit better into smaller enclosures.

arduinorev31s

 Connecting all the bits

This motor aint gonna move without no juice! Lets get connecting this thing up.

  1. Firstly connect the +5v power on the arduino board to the +5-12v pin on the ULN2003 controller
  2. Next connect the negative (GND) on the arduino board to the -5-12v pin on the ULN2003 controller.
  3. Next connect Arduino pins 8, 9, 10, & 11 to pins 1, 2, 3 & 4 on the ULN2003 controller, respectively

Excellent, now that we are all wired up we need to instruct the Arduino board how to use the controller and motor. So lets take a look at a simple arduino stepper control. Note, this source is already provied with the Arduino software in the examples menu.

 /* 
 Stepper Motor Control - one step at a time
 
 This program drives a unipolar or bipolar stepper motor. 
 The motor is attached to digital pins 8 - 11 of the Arduino.
 
 The motor will step one step at a time, very slowly.  You can use this to
 test that you've got the four wires of your stepper wired to the correct
 pins. If wired correctly, all steps should be in the same direction.
 
 Use this also to count the number of steps per revolution of your motor,
 if you don't know it.  Then plug that number into the oneRevolution
 example to see if you got it right.
 
 Created 30 Nov. 2009
 by Tom Igoe
 
 */

#include <Stepper.h>

const int stepsPerRevolution = 2048;  // change this to fit the number of steps per revolution
                                     // for your motor

// initialize the stepper library on pins 8 through 11:
Stepper myStepper(stepsPerRevolution, 8,9,10,11);            

int stepCount = 0;         // number of steps the motor has taken

void setup() {
  // initialize the serial port:
  Serial.begin(9600);
}

void loop() {
  // step one step:
  myStepper.step(1);
  Serial.print("steps:" );
  Serial.println(stepCount);
  stepCount++;
  delay(1500);
}


As you can see, the code is fairly simple. Once you have entered the code into the Arduino you can connect the USB and upload your new controller to the Arduino board.

With a little luck, once this is done you should start to notice that your motor starts to make fine movements. As with most software, you can make adjustments. Here are my tips:

Play with the delay time, which is measured in miliseconds:

delay(1500);

Also, check your motor’s data sheet to see how many steps per full revolution it can make, as this can also be set in the software:

const int stepsPerRevolution = 2048;  // change this to fit the number of steps per revolution
                                     // for your motor

Have Fun – In part 3 we will combine the electronics with an enclosure and a GoPro tripod mount and see what happens.

Missed Part 1 – read it here….

Chillout video featuring Seascapes Album

I’d like to share some stunning video footage from Paul Dinning, who produces some of the best landscape and wildlife films I’ve seen. Together we embarked on a project to mix his visuals with my music. The result is below. This film was largely shot around the Isles of Scilly.

Please check out Paul Dinning’s YouTube channel “Wildlife in Cornwall” here:

https://www.youtube.com/channel/UCPJXfmxMYAoH02CFudZxmgg

 

First bike ride of 2015

I guess I left it quite late to start getting out in the fresh air and doing some excercise but it was worth waiting for today’s weather, perfect sunshine and a slight breeze to keep me cool.

20150419_120545

I dug my old Kona mountain bike out of the garage and gave it a quick once-over to make sure it was roadworthy. A bit of WD40 on the brake calipers and some air in the tyres – ready to roll.

I decided also to mount my new GoPro on my lid to get some video of the journey. I planned to take a route around St. Agnes beacon and the surrounding area, including some off road trails near Chapel Porth and Wheal Coates mine. A born techy I also decided to take ‘MapMyRide’ – a GPS tracking app on my Android phone to record my every move (and stop). The map below is courtesy of this great app and shows the circuit I rode.

bikeroute

The first half mile of my journey was pretty much flat or down hill so I felt like I was off to a great start. When I hit the bottom of the hill however, things changed. For starters, I got my gear selection the wrong way around and came to a grinding halt. I switched the GoPro off, turned around and sorted my gears out before the first ascent. I reckon I got about 70% up the hill and then stopped for a rest. 20+ years of smoking taking its toll even though I haven’t smoked for 2 years now.

20150419_115657

This pattern of high speed downhills, slower flats and very slow ascents continued for a while until I got to my main destination – Wheal Coates Mine, overlooking Chapel Porth. This signified the end of the road section for the time being and the beginning of some off road fun. You can see this area on the map above, indicated by a green circle.

20150419_115512

The off road stuff was largely loose shale and the occasional dog walker, complete with dog. I haven’t done any off roading for about 10 years so I was a little nervous to start with, but after a few hunder yards I felt comfortable again – its like riding a bike I guess!

I continued downhill at a fair old lick and headed over to one of the abandoned engine houses where I sat for 15 minutes to watch the sea rolling in over the golden sand below. It was stunning – if you’ve never visited the north coast of Cornwall, you ought too.

The only problem with getting to the bottom of a trail is getting back up again. My fitness didn’t allow me to cycle the whole way up in one go so I stopped every few hundred yards and took in the view whilst regaining some energy. Eventually I was back on the road and continued the circuit back through St. Agnes and along the back roads to Mount Hawke.

I’m looking forward to the next trip now.

 

 

USB: The not so ‘universal’ serial bus

usb_connectors

I’ll open this article with a quote from Wikipedia on the so called industry standard, USB.

Universal Serial Bus (USB) is an industry standard developed in the mid-1990s that defines the cables, connectors and communications protocols used in a bus for connection, communication, and power supply between computers and electronic devices.[2]

USB was designed to standardize the connection of computer peripherals (including keyboards, pointing devices, digital cameras, printers, portable media players, disk drives and network adapters) to personal computers, both to communicate and to supply electric power.

I wouldn’t like to try and count how many USB enabled devices there are in my house, but one thing I’ve noticed more and more recently is a lack of compatibility with USB cables.

According to Wikipedia’s excerpt above, USB not only defines connectors and protocols, but also the cables. In an ideal world it should be possible to carry only one cable (of each connector size) around with you, and it should fulfil all your requirements. So, why is it then that some of my USB cables only support power and charging – for example USB cables associated with power banks, portable speakers etc. If I were to try and sync my android phone with one of these, it wouldnt work. I’m not sure if this is so much a problem with the full size USB connector, or even USB mini, but I have definitely noticed issues with my USB micro connectors.

usbconnectors

The pinout diagrams I’ve seen all seem to have the same configuration, so can anyone tell me why certain cables will not sync data with my devices, and others don’t seem to pass any charge to the device on the other end. I find this very confusing and frustrating, and currently seem to have three or four cables in my bag at any one time.

Any ideas folks!

How to configure your Beats Wireless headphones to work with Google Play Music

I quite often use my Beats (by Dr Dre) Wireless headphones with my Galaxy S4 android phone. However what I noticed was that by default, if I used the Play / Stop buttons on the headphones, that this would launch the built in Samsung audio player instead of controlling Google Play Music – my preferred audio player. beats This morning I found a neat little app called “Headset Control” (link below) which allowed me to choose my preferred audio player, which now makes by Play and Stop button control Google Play Music instead. Result! Please note, I am not affilliated with this app in any way – I just really like it.

https://play.google.com/store/apps/details?id=com.danez.headphonecontroller&hl=en

Once you have downloaded the app its fairly straight forward to configure.

  1. Launch the “Headset Controller application”.
  2. Click on the “Select your preferred player” which is the first menu link.
  3. When the popup appears simply scroll down the list until you find “Google Play Music” and then click on it.
  4. You can exit the application now.

Job done, you should be able to control your Google Play Music application from your headphones now.

How to build an electronic timelapse auto panner – part 1

You’ve probably seen many timelapse videos now on YouTube and Vimeo where the camer appears to be moving whilst the clouds shoot by. It turns out that the camera is just set on either a rotating base or slides along a trolley at very small increments. Over time it gives the appearance of a full pan. I did a little research and it seems that many people use bastardised egg-timers (the clockwork kind) and mount their camera to the top of it. I of course like the simplicity of this, but as a techno-geek I want something a little more interesting than that. My project is to build an electronic panner which meets the following expectations:

  • uses a stepper motor to make the small rotations needed.
  • the unit will need to be self contained
  • runs on a 9volt battery
  • has a tripod mount on the bottom
  • has a variable speed control

Sounds adventerous eh! Before I go into the ins and outs of how I intent to make it, I’ll show you roughly how the thing will look.

20150413_181803

Read Part 2 here…