Monday, May 23, 2016

DIY stretched canvavas to LED strip backlight mod Part 1 and Part 2

Installing an LED strip behind a painting hung on a wall creates a nice lighting effect that highlights the artwork as well as providing a soft ambient light in the room. The electrical parts were sourced via ebay for about $10 to $20, while the PVC parts came from a local hardware shop. The following documents the evolution of this DIY project in two parts, 1) a simple stretched strip, and 2) upgrade to PVC molding.

Part 1

It is important to offset the painting from the wall, so that the LED strip has a place to sit as well, and has sufficient space for the light to leak out.

On the back side of the frame, install 4 screws at each corner, about 1 inch from the edge of the frame. Leave enough of each screw end to string the strip around it (about 10 to 15mm depending  on the screw head and any loose canvas that my interfere). Finetune the screw lengths by hanging the painting, pressing on each corner in turn and checking for a wobble. In a way the whole assembly should be like a table with four legs -- it should not wobble.

Secure the LED controller module and 12V power cable so that the power cable exits the frame on the lower middle edge, to go to the power supply plugged into the wall. You can use safety pins and attach to the loose canvas at the back that had been wrapped around the frame, or any other means available. You need to have enough tension for the strip so that the lights point outwards. This can be done by securing the power end to the frame, going around the screw corners and setting up a small loop at the other end by using the adhesive backing. You don't want too much tension (as that can damage the strip), or too little (as the light may not be uniform). It is important to cut any excess LED strip length in a suitable place (in this case I only used about 3m out of the original 5m strip).

Rev 18 July 2016:
Did the second painting today.

What I wished for today was to get some rigid L shape pieces to mount the strip on under the frame, although it looks like I will never make the time to go to the hardware store any time soon; maybe in the next iteration.

Part 2

Back in mid 2016, when this project started, getting a quick win was the priority. It was worth it! In everyday life, these lights proved to be practical for their functionality, with a dimmable remote, as well as providing a wonderful relaxing evening atmosphere. However, it was always a longer term view to install these lights properly on a rigid structure.

The advantages of this higher quality finish include: 1) improved illumination uniformity via diffuse white channel, 2) preventing twisting and sagging of the LED strip, 3) improved mechanical resilience against bumps and handling.

The following illustrates how I installed PVC moldings to the frame.

Saturday, May 21, 2016

Friday, May 20, 2016

DIY 18650 battery hack conversion

The great reason for adapting 18650 batteries to work with your everyday gadgets is this:
In my humble opinion, I think 18650 batteries are an awesome upgrade to the humble old timey AA. They charge much faster, hold more energy, and in recent years had become super affordable at something like a dollar a piece. If you are reading this on an average laptop then there are probably three of them inside it -- try doing that with AAs!
IMPORTANT: 2xAA ~= 1x18650

To get started you will need:

This is going to be a growing list of gadgets to which I applied the 18650. The results are not pretty but this is not called fashion either:

  • Photography flash trigger (originally 2x AA, replaced by 1x 18650) and receiver (originally mini 12V, replaced by 1x 18650)
  • Speedlight portable flash (originally 4x AA, replace by 2x  18650)
  • Hair trimmer charger (originally a proprietary wall-wart with quite a long cable, universal AC to 3.7V, replaced by 1x 18650)
  • medium power bike helmet light, made from 1x front froglight + 1x tail helmet light -- RIP
  • Bluetooth speaker that worked on 4xAA, now works on 2x18650, the batt door does not close but that's a todo for another time. -- RIP
  • Ikea cordless screwdriver, even though it had a 18650 built in, it got converted to a external plugin config. This way when it runs out of charge, a fresh battery can be plugged in and work can continue.

Thursday, May 19, 2016

speedlight speedlite flash 18650 lithium battery hack

In my humble opinion, I think 18650 batteries are an awesome upgrade to the humble old timey AA. They charge much faster, hold more energy, and in recent years had become super affordable at something like a dollar a piece. If you are reading this on an average laptop then there are probably three of them inside it -- try doing that with AAs!

It is baffling why camera gear manufacturers haven't adopted 18650 batteries yet. You can find 18650 in everything now, from Tesla cars to high power flash-lights, USB power banks, and most laptops. My friend pointed out that the average photographer doesn't like change, had to be dragged kicking and screaming to convert their workflow from film to digital, and AA is something that they understand.

Recently I tried to find evidence that hands-on DIY MacGyver type photographers are using 18650 with their flash units and cameras only to find an unconvincing adaptation of the idea, or reasons against it (this had to do with maximum available current, which is contentious depending on who you ask).

I had to try it for myself, so I ordered some 18650 battery holders from ebay.

My initial conclusion is: SUCCESS. It seems to work just fine. What you see here is not pretty but it works. No doubt future iterations will expect to look more glamorous and more resilient to work in the field.

Yes, there is a major current train during capacitor charging, but it lasts for only about 2 seconds on charged batteries on maximum setting (1/1), while a blink of an eye on minimum (1/128). After a few cycles of maximum discharge you can feel the batteries get slightly warm. On a real shoot one would be swapping out a stale set for a fresh set as needed, and not wait to run the batts into the ground, so I'm sure this will work out just fine, and you can pack a lot more power now.

Here is some voltage readings. The low blip is just after a full power flash went off.

Will update this post later, when there is new information.

In the next iteration removed most of the rubber bands

Tuesday, May 17, 2016

Hello World via Google Cloud Platform GCP

No, this isn't strictly speaking Ubuntu related, and is at best most general regarding web servers. However my new tech toy is Google Cloud Platform used to set up a web server to operate a landing page. I have been putting this off for too long, but finally got my toes dipped. Opted for the free trial, you should go for it too, but don't waste it.

Here is a primer, but I did not have time to watch it yet:

Here is on how to make a LAMP stack, but I stopped at LAP, with an ubuntu image:

Here is the cockpit:

Here is on uploading files to your new server, which took me 90 per cent of my initial setup time until I figured out what's what:

Once it is running and you just changed config, remember to restart
sudo /etc/init.d/apache2 restart

Made a landing page:
I wonder how effective would it be to operate without a domain indefinitely.

Update: upgraded the ip url to a domain url,

Friday, May 13, 2016

VLC audio tape record notes

Here are some notes on how I transferred my friend's tape to mp3. VLC gives you a WAV file. I used kdenlive to make a project and export it to an MP3 file. The WAV keeps all of the hiss as it comes from the tape; exporting mp3 at q7 takes the hiss out; mp3 at q10 keeps some of it and other subtleties if you need to preserve them.

Thursday, May 05, 2016