Darker than Black Hei's Dagger Replica Project

Metal Version Rev 2.5 + Sheath

Blade:  440C stainless steel, hardened, sharpened Handle:  6061 aluminium, black anodized Sheath:  3D printed (SLS) polyamide, spray-painted black Rev 2.5 incorporates some minor feedback I had for my supplier on Rev 2; the core design remains the same. This is an extra that I'm considering selling for around $500.  It just came in recently and it looks pretty good.  Let me know if you're interested in purchasing it. This is probably the only blade that I'll make available for sale to the general public, and one of only four that I've had made so far. Note that the tip on this particular blade didn't end up quite as sharp as the other blades I received; I sharpened it up a bit with my rotary tool so it's still reasonably sharp.

My Shapeways Shop:  You can order a Nylon 12 / Polyamide 3D print here - this is my recommended material for the prop version thus far - note that you will need to sand and paint the part yourself which takes some skill
My eBay Items:  I've currently sold all of the extra prop versions that I had laying around, but if I get additional requests I may get some more to list up here.

Project Overview
Not to be satisfied with other creations I've seen online, I set out to model Hei's dagger from Darker than Black with CAD so that I could have it accurately fabricated for me and easily reproducible.

Here's a rendering of the model I made - I used various screenshots and scans from the series as reference to make it look as authentic as possible.  The layouts that Volphin provides on his website were also a big help, though I did not follow them exactly and you can see the profile in my rendering is a bit different.

I am making a prop version that would be safe for bringing to events as well as a battle-ready metal version that Hei himself could use.  I've made the prop version an open design and anyone who wants it can download the model in .stl format at my shapeways shop.  If you want it in another CAD format shoot me an email and I can export it for you.

The metal version I made more or less exclusively for myself but if there are about 5-10 people that can commit to purchasing I could potentially make a batch order with my machinist.

Please post any thoughts you have in the comments below!

ODAC Output Switcher

I wanted to use my ODAC as my central PC audio device so I needed it to be able to output to either 3.5mm (to headphone amplifier) or RCA jacks (to active monitor speakers), but I didn't want it outputting to both at the same time to prevent unnecessary loading. I ended up implementing a tiny little board that simply routes the audio signals through a 3PDT switch to either output jack. You can see what it looks like in the image gallery above. It doesn't exactly look elegant as I more or less just glued the board to the top of the ODAC case, but it gets the job done.

DIY OVC3860 Bluetooth Receiver / PKB-PCBA Evaluation Board

Introduction
Continuing on my quest to get good audio from my phone to my car's aux in I started playing around with bluetooth receiver modules.  The ElectroDragon PKB-PCBA caught my eye as a fairly easy to implement solution that offers potentially good quality for the price.  It uses the OVC3860 IC which I've heard good things about and also features a SGM4917 headphone amplifier IC which appears to be a fairly handy part with both integrated click/pop suppression and charge pump circuitry to generate it's own negative rail for producing a ground referenced output.  Many of the other similar boards I've seen use a basic opamp with a single supply and bulky capacitors at the output to get rid of the resulting DC offset.  I believe this is the main reason for their poor performance.

As with all of these Chinese made modules English documentation is sparse at best for the PKB-PCBA and ElectroDragon support was utterly useless as well when I tried to ask for more specifications.  Fortunately whoever designed the board had easy implementation as a goal and pretty much all you need to do to use this thing is just feed it power and get your audio output from it.  I don't know the exact schematic of the board but it probably looks similar to this application circuit for the BLK-MD-SPK-B which looks fairly solid to me.

If I wanted a more audiophile grade solution I could try to lay my own PCB using a Roving Networks / Microchip RN52 Bluetooth Audio Module with a TPA6138A2 from TI driving the output, but I don't have the equipment or experience needed to take measurements for optimizing the layout/performance of such a design and it's really just too much work for me.  My approach of using a highly integrated module saves a lot of time and still yield respectable performance.

Note that I tried the Griffin Technologies BlueTrip Aux (it is one of few commercial products low profile enough to plug-in inside my car's center compartment) before pursuing a DIY solution and found that the BlueTrip outputs a low volume signal with completely non-existent bass.  My music simply sounded so terrible that I returned the BlueTrip immediately after testing it.  The funny thing is that I was contacted by another BMW owner about my Amazon review who had the same issue with the BlueTrip so I know it isn't just me.

Mediasonic HFR2-SU3S2 RAID Enclosure Review & Fan Replacement

Introduction
The Mediasonic HFR2-SU3S2 is a nice little USB3.0/eSATA HW RAID box that's perfect for various storage applications. Personally I use it in RAID5 mode over USB3.0 with 4x SAMSUNG EcoGreen F4 ST2000DL004 2TB hard drives for backup and media storage.  It has been working for almost two years now without a single hiccup and even when a hard drive died it proceeded to reconstruct my array with a replacement drive without any problems.

The Mediasonic HFR2-SU3S2 has a reasonable MSRP of $199.99 but can often be found on Newegg with a rebate or promo code (or even both) which brings the price down to around $129.99.  This is a great price for a plug and play USB3.0 hardware RAID box.

Manufacturer Page: http://www.mediasonic.ca/product.php?id=1358153144
Newegg Page: http://www.newegg.com/Product/Product.aspx?Item=N82E16816322004

Car 12V Cigarette Lighter Receptacle Power Isolator Circuit

Introduction
An age-old issue of mine was having to jack the volume on my car stereo (2008 BMW 328xi) way up when playing music from my phone (Galaxy Nexus) over the 3.5mm aux connection.  I actually tried using a bluetooth receiver from Griffin Technologies to solve this problem but only found that I had to jack the volume up even more and that the whole bass-band disappeared when using it as well.

I found, however, that using my Objective2 headphone amplifier to amplify the aux in would both solve my low volume issue as well as make my music sound better in general.  It was clear to me that a basic amplifier typically used for headphones would probably do the job, but I wasn't willing to swap out or recharge batteries every now and then to deal with it. (especially since I'd always accidentally leave the amp on after exiting my car)

The 12V power from a car's cigarette lighter is far from I an ideal power source, and in many vehicles it shares a common ground with everything else in the car.  This leads to a lot of common noise and will also end up blowing up amplifiers using a virtual ground scheme such as the cMoy if you try powering them directly off car power. (as the stereo may also share the same common ground)

Project Overview
I ended up making a fairly basic circuit which consists of only 3 ICs.  It basically takes in the 12V from your cigarette lighter and produces a regulated, isolated 12V output.

This powers a cMoyBB from JDS Labs which is configured with a gain of approximately 5.  Since the cMoyBB board is nice and compact I'm able to cram my circuit in there right next to it.

I'm using pretty much as much heatsinking as possible on the LM2937 as it really does get quite hot.  The cMoyBB only draws about 40mA of current even while playing music into headphones but the LM2937 has to deal with almost 300mA coming into it since it's driving the rest of the circuit.

Objective2 Headphone Amplifier SS Front Panel

Machined 304 Stainless Steel O2 Front Panel Rev. 2

Buy one of my new Rev.2 panels directly from me! The panel and holes are laser cut from 304 stainless steel and the lettering/symbols are chemically etched into the surface of the panel and then filled in with a dark black paint. This yields a far nicer and more wear resistant appearance than the typical silkscreening or laser engraving processes used for most panels. These panels fit the "stock" Box Enclosures B2-080 enclosure. Please ensure that your address on file is correct and in USPS standardized format. All sold as of 2/20/2013!  I could have another batch made if there is enough demand but so far the batch of 20 has not been profitable for me and it doesn't seem like there is much interest.  Be happy if you're one of the few people that managed to get one!

Introduction
When I decided to build a batch of five O2 amps with my friends I, like many others, went to JDSLabs to order their aluminum front panels.  When I got them, however, I was honestly rather disappointed - it looked all shiny and nice in the pictures on their website but the actual parts I received looked fairly lackluster and were rough around the edges.  I wasn't a big fan of their company logo on the front panel of my DIY amp either.  I decided to fire up my CAD program and look into getting some nice stainless steel panels custom machined for me...

DIY Audio Forum Thread

Rev. 2
This revision features chemically etched lettering and symbols filled with black oil-enamel paint and uses a #4 (brushed) finish rather than 2B.  The panel material remains 304 stainless steel and it can be either waterjet, laser cut, or CNC milled depending on my supplier's capabilities.

Overall I think it is much nicer than the panels from either JDSLabs or Head 'n' HiFi though admittedly it's a good deal more expensive to manufacture as well.

Here are some images of my initial prototype batch of 20 with Kunshan Krell:

For a production batch of 100 I can easily hit a $12 price point.  The main problem is that I never wanted to commit the investment for such a large batch since this isn't my full time job and I don't want to potentially end up sitting on a large pile of these.

Rev. 1
I had originally meant for these to be produced on a larger scale, but they ended up costing over $30 each to make and community interest did not seem to be there.  I went and had two of them machined anyway since a friend and myself each wanted one.  The panel and holes were laser cut from 2B finish 304 stainless steel, and the lettering and symbols were subsequently laser engraved.

Here are some pictures of how it looks:

You can see my holes fit a lot tighter around the buttons so they're not slopping around at all - also since the panel is thicker (~0.1") the 3.5mm jacks don't protrude out as much.  The lettering was a bit lighter than I'd like, but is quite wear resistant due to the laser engraving process as opposed to the silkscreening used on most front panels.

Sadly I scratched one of them a bit when I unpacked it with my knife, but luckily I able to patch things up somewhat by sanding the part down with 220grit sandpaper.  It kinda has a brushed look to it now too.
Silly me needs to stop knifing everything...