Loooooong Exposure Photography

One of the most fascinating domains of photography for me has always been Long Exposure Photography. Whether its capturing motion of a few seconds by some performer, photographing the night sky or a waterfall, light trails or light painting, I always try and see how I can incorporate it into a scene.

Here are some of the best articles I’ve seen on this topic:

http://digital-photography-school.com/8-tips-for-long-exposure-photography/

http://digital-photography-school.com/long-exposure-photography/

And here are some of my attempts in this domain.

I hope to keep this post alive later on by adding new photographs that I capture using this technique or in case I find some of my previous good ones 😀

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DIY Portable Speaker Amplifier using LM386

For one of my first audio circuits, I decided to make a simple amplifier circuit based on the LM386 IC to power an 8 Ohm 0.5 W Speaker. I started off based on the schematic provided in this instructable:

http://www.instructables.com/id/Portable-Speaker-1/?ALLSTEPS

But once I was done with it, I wasn’t really impressed with the audio quality. The audio would start to crackle really soon and there was very little clarity. As it turns out, all I had to do was add a 0.047 uF capacitor at the output and a 0.01uF capacitor  at the input as decoupling capacitors to get a remarkable upgrade. The more common schematic for this application was available at:
http://www.instructables.com/id/Make-a-Simple-Audio-Amplifier/

Oh and for anybody interested in making this project, do check out this awesome detailed post and video by Hackaday:
http://hackaday.com/2011/05/01/lm386-altoids-tin-amp/

and the original hackaweek post:
http://hackaweek.com/hacks/?p=131

So effectively the schematic I used resembles:

(http://hackaweek.com/hacks/wp-content/uploads/2011/04/LM386ampschematicfinal1.jpg)

In order to test my amp, I even wanted to try using an Arduino to drive this speaker instead of the usual annoying Piezo Buzzer I’d used so far for audio output. I used the sample code from the tutorial dealing with the tone() function in Arduino:
http://arduino.cc/en/Tutorial/tone

Here are some pics of my implementation:

And here’s how it sounds:

Future Plans:
1. Adding a bass boost as mentioned in the reference post
2. Trying out a guitar input and output to headphones
3. Putting it in a case

Running the Nokia 6610 LCD with a Raspberry Pi

A while back, I’d bought the Nokia 6610 LCD thinking of it as a nice cheap display to incorporate into certain projects.

http://www.onlinetps.com/shop/index.php?main_page=product_info&cPath=9_41&products_id=776

When I finally got around to using it, I thought of looking for instructables/references on interfacing it with the RasPi, but all I found was:

https://www.sparkfun.com/tutorial/Nokia%206100%20LCD%20Display%20Driver.pdf

and

http://www.instructables.com/id/How-To-Use-a-Nokia-Color-LCD/

and slowly learnt that this particular display has been quite a challenge for the online community for a while now. I did find very nice posts about how to interface it with other platforms though:
Arduino:
http://playground.arduino.cc/Code/LCDPCF8833

AVR:
http://thomaspfeifer.net/nokia_6100_display_en.htm

But after a lot of hunting, once I started looking for projects based on the LCD’s drivers, I finally came across a github project:

https://github.com/engpedrorafael/pcf8833

I really felt a rush of gratitude towards him once I found this because the task of porting the entire C library to be used with the Raspberry Pi through Wiring Pi seemed too daunting to me. Or atleast something I’d be too lazy to do to run a simple colour LCD 😛

All the steps for running the LCD are there on his git page. In short,
1.Make the connections:

(LCD connections)

2. Get his code
3. Run it and test, convert images to the relevant dimensions (132×132 pixels) and file format, and use the python modules he’s created.

I just hope this post helps somebody else find this particular implementation much sooner that it took me considering how easy things became once I found this. Major props to Pedro. 🙂

In terms of connections, I ended up using a 330 Ohm resistor between 12V and the LED+ pin to make the display bright enough, I tried to use the 7806 but IMHO the display wasn’t really readable.

Here’s my setup:

P.S.: In case anybody’s having issues running the D-Link DWA 132 N300 Wi-Fi Dongle with the Pi, check out:

https://xneosis.wordpress.com/category/linux/raspberry-pi-linux/

Works like a charm and the dongle is one of the most reliable ones I’ve used.

P.P.S.: If you want to make your own bench power supply and haven’t seen this yet, check out my post:

https://botmayank.wordpress.com/2014/06/24/diy-bench-power-supply/

DIY Bench Power Supply

For any electronics hobbyist, one of the most crucial tools while testing/prototyping circuits on a breadboard/perfboard is a good standard power supply. But buying a typical bench power supply might not be an option for everyone.

One of the easiest (and perhaps the most useful) hardware hacks I’ve ever done is to re-use a really old PC CPU’s ATX power supply as my own bench power supply. Earlier I used to keep leeching 5V or 3.3V DC off of Arduino Uno boards powered through DC 9 V Adapters and I’d always have to use DC jack to molex or other such types of connectors in conjunction with a plethora of DC adapters to power my breadboard prototypes.

Now, I can easily use this setup to have easy access to 3.3V, 5V and 12V each capable of sourcing 3 A of current too! 🙂
The best part is, there’s really not much that you need to do to get it up and running!

Here’s what an ATX power supply looks like:
http://www.ebay.in/itm/like/intex-450w-smps-atx-power-supply-sata-connectors-/271505046206?pt=in_computer_components

You can get one for around INR 800 (13 USD) easily from a local computer hardware store or online.

Here’s the pinout of the connectors on such an ATX supply:

atx-psu-pinouts
(http://www.helpwithpcs.com/courses/power-supply/atx-psu-pinouts.gif)

As you can see on the main ATX 20 pin connector, most of the standard operating voltages that we need for any electronics projects are right there! The only hitch is, you can’t just plug it in, flip the switch on the back, and make it run.

Remember how your PC CPU powers up? You have to push the power button right? The connection responsible for the powering up is the PS_ON pin shown there. For our purposes, we simply have to short that with GND to get the power supply up and running. So you could simply snip, strip and twist them together, or as I’ve done in my case, connect it to a small slider switch.

DSC_0675     DSC_0678

As for the other supply voltages, I’ve stripped them and connected the wires into this small “distribution circuit” which is essentially just screw terminals for the 3.3V, 12V, 5V, GND wires along with rows of male headers for the same along with a “Power On” green LED and the slider switch. You could even use the ATX 20 pin connector as is, but the molex connector on that has sockets that are larger than the usual breadboard hole sized male headers and that is why I went in for such a setup. ….and we’re done!

I found plenty of instructables online for setting this up and I thought that I could just help add to the list of resources out there so that more people starting off into DIY electronics or budding “Makers” could maybe have some easy access to these common voltages with very little effort, time and/or money.

TL;DR:

Step1: Get the ATX power supply
Step2: Short the Green wire with any one of the black wires on the 20 pin header
Step3: Solder a small perfboard distribution setup if you want
Step4: Plug it in, and DONE! Hookup your breadboard circuit and enjoy!

P.S. Be safe while dealing with the power supply and handling AC voltage and do leave room for the cooling fan at the back of the ATX power supply box

Some more pictures of my setup :

I even hooked up a push button switch and 2 wires to a small DC motor that I can drive with this supply. I intend to fix standard PCB Drill bits with it by gluing the chuck that I can take out from a normal hand press PCB drill in order to have a neat automatic PCB Drill for any prototype PCB’s I make at home with the toner transfer method. I’ll post that as soon as I’m done with it.
Cheers!