BMW E90 Dash Cam Hardwire

BMW E90 Dashcam Hardwire

My goal here was to have a dash cam setup for driving and parking with wires completely concealed for a fully integrated appearance. My original thought was to use a single Vantrue N2 Pro dash cam with one camera facing rear and one facing front. I planned to mount it on the rear interior lighting module but the front mirror blocks a good view of the road from that angle so I ended up purchasing an additional VIofo A119V2 for the front camera and just used the Vantrue as a rear/interior cam.

Behind Sofa Wall Shelf /w Outlets

Here's a random idea for something handy to put behind your couch rather than a sofa table.

Behind Sofa Wall Shelf

This shelf was created for me by Intrigue Custom Creations of Scottsdale, AZ:  http://www.custommade.com/by/intrigue/

4/4 solid red oak was stained /w Minwax 215 and then topcoated /w semi-gloss Arm-R-Seal.  Overall dimensions of the shelf are 120" L x 14" W

Project Drawing:  https://1drv.ms/b/s!AkDiurnLC4Frh6wEO0LJH7Jvu8V5TA

Custom Battlestation Computer Desk Design

This is a design that I previously submitted on Imgur / Reddit.

Yangorang's Custom Battlestation Desk & Mancave

As with most of my custom stuff this was the result of my annoyance with existing products on the market.  I wanted a much larger desk than most as I like to put a lot of stuff on it, and I wanted a keyboard tray wide enough to accommodate my CAD mouse and a super large mouse pad.  While I was at it I stuck in some integrated cord management and a little shelf for my active studio monitor speakers.

Darker than Black Hei's Dagger Replica Project

Darker than Black Hei's Dagger Replica Metal Ver Rev2.5

Thingiverse:  You can download the STL from here to get the prop version printed - note that you will need to sand and paint the part yourself which takes some skill.

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 Thingiverse.  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 and a few friends.  I'm sure a lot of people would love to have one but few want to pay $500+ to have them custom made.

Please post any thoughts you have in the comments below!

ODAC Output Switcher

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.

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.

Purdue Engineering Fountain Model

Back when I was in high school I was asked by my boss to create a nice gift for a Purdue professor....this is what we came up with.  He was generous enough to give me one too!

Objective2 Headphone Amplifier SS Front Panel

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

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.  You can see from the images that my panel is slightly thicker and fits more tightly around everything.

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

Machined Stainless Steel Objective2 O2 Front Panel

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.

50->60mm Fan Adapter for ASUS SABERTOOTH P67 Motherboard

I got a bit annoyed at all of the rumbly 50mm fans I had to keep swapping out on my ASUS SABERTOOTH P67 Motherboard and decided to get a little 50->60mm adapter machined for me so I could use a nice 60mm ball bearing Vantec Stealth fan instead.
I tried multiple different 50mm models from EVERCOOL and Rasurbo but all of them started rumbling within a month or so. The 60mm Vantec Stealth has been going strong for almost a year now and yields slightly higher airflow as well.

I use OnlineMachinist for most of my DIY machining needs - they offer reasonable prices and are easy to work with.

Linear Regulated USB Isolator

Introduction
This is a pretty short and simple project – as you might be able to guess from the title it’s essentially an adaption of the USB Isolator from Circuits@Home except with the whole switching power supply section cut out and a LM340-5.0 based linear regulator section spliced in there instead.  The pin header to switch between low/full speed USB mode is eliminated as well and this version is locked to full speed operation.  I've also added in a little power LED to let you know things are working.  Full credit goes to Circuits@Home for an overall excellent original design.

I intend for this thing to be used as a sort of isolator dongle for USB DACs and other devices that want cleaner 5V power than typical switching regulators or USB bus power offer.  The assembly is kept very low profile with the use of mostly SMD parts.

Linear Regulated Power Supply (Fixed)

Introduction

This is an easy to assemble, all-in-one linear regulated power supply solution.  It utilizes a TO-220 form factor positive fixed linear regulator such as the LM340 or LM78xx series and takes an input voltage of up to 35Vpk from a wall transformer based on the regulator used.  The fuse, switch wirepads, and all of the linear power supply circuitry are integrated on one board – it is meant to be used inside of a HAMMOND project enclosure and all it needs is reduced VAC from a wall transformer of your choice to function.  DO NOT connect this directly to the line AC from your wall outlet, as you will simply fry pretty much everything on the board with the high voltage!

I think this project will make a good project for beginner hobbyists or those who need a simple but good LRPS.  I don't intend to sell it as a kit or fully assembled since this is supposed to be a DIY project after all.

I realize that there are a lot of other LRPS designs out there already but I think this one has its merits or I wouldn’t have bothered putting it up.  In fact I’ll list a few alternatives right here for you to check out and compare for yourself:
AnalogMetric LV30 LRPS
NightFire Kit #1772
AMB σ25 Regulated Power Supply

Theory of Operation

A reduced VAC (ex.16VACrms) comes in from your wall transformer to the board.  CSH shunts away high frequency line noise and transients.  Five fairly large reservoir capacitors come after the full-wave bridge rectifier to provide an excellent unregulated DC signal.  A bleeder resistor (R2) is implemented for safety purposes.

 

CBY bypasses the input to the voltage regulator IC and helps reduce input ripple.  The 1N4002 diode is implemented as a protection diode for the regulator IC.  Electrolytic, tantalum, and ceramic capacitors (C5, C6, C7) are paralleled at the output of the regulator in order to provide excellent transient performance and low impedance over a large frequency range.
 

Input/output power and your on/off switch are hooked up by terminal blocks which accept between 26-16AWG.  (I recommend you use at minimum 24AWG)  I find that these work fairly well and provide an easy means of wiring stuff to the PCB.  A fairly large ground plane is implemented in order to reduce noise and minimize stray inductance among other benefits.

Project Resources
Schematic
Board Layout - Board layout is 1:1 scale so you can print it out if you want to get an idea of the dimensions

EAGLE Project Folder