For Christmas I got a new Otterbox case for my Galaxy Note 4.  Since the Otterbox is significantly bigger than my old case, it forced a a revision of my car Galaxy Note 4 Car Dock.

Rather than simply increasing the size of the Car Dock, I set out to add several new features:

• Integrated QI Wireless Charging
• 4G LTE Cellular Amplifier
• NFC

Wireless Charging

To add Wireless Charging to the Galaxy Note 4 all you need is a QI Sticker and a QI compatible wireless charging pad.

The QI Sticker I chose includes a separate antenna for NFC.  This is important because many cheaper QI Stickers render the NFC inoperable.  The QI Sticker installs inside the phone between the battery and the back cover.

The QI charging pad I chose is pretty much the cheapest one out there.  It is a single coil design so the phone placement is critical.  I found that the phone has to be in the exact perfect spot or else it will not charge at all.  Despite perfect placement, I find this charging pad to be extremely slow.  Hopefully it will keep up with my in-car entertainment and GPS usage during long trips.

Back to the Drawing Board

My original Galaxy Note 4 Car dock was designed in Solidworks, revising the 3d models was easy.  For the second revision I simply measured the new Otterbox case with my calipers and revised the dimensions for the Galaxy Note 4 model I had created previously. Thanks to the equation based design constraints,  the brackets automatically scaled to fit the new phone dimensions.

4G Signal Amplifier

I’ve found T-Mobile reception to be pretty spotty, so I wanted to add a signal amplifier to help improve the range.

The signal amplifier kit consists of three parts:

• Amplifier
• Exterior Antenna
• Interior Antenna

The Wilson amplifier kit I chose supports 4 signal bands and appears to actually have some clever design features including feedback-loop detection.  I was pleasantly surprised by the build quality.

The product seems to work fine, and the number of bars on the phone definitely goes up.  Unfortunately, if the phone is only getting 2G/3G, then after amplifying it still only gets 2G/3G.  I suspect this may be because some of the cell towers don’t actually support 4G LTE.  I wasn’t expecting miracles, however I’m not sure its worth the price.

Final Assembly with NFC

I printed and assembled the new car dock design on my Ultimatker 3d printer and had the new assembly up and running in just a few hours, not including the shipping time for the various products.

NFC was added using a Samsung Tectile.  Using the Xposed “NFC LockScreenOff Enabler” module I was able to configure the phone to automatically unlock when placed in the dock.

On its own, the NFC works great, but since NFC and wireless charging use similar frequencies, the charging pad drowns out the NFC signal.  The next revision of the dock will use a bluetooth connection to determine the lock status instead.

Bad Power Source

I created this bad power source for my workbench to aid in debugging and validating some of the high
voltage projects I’ve been working on.   The goal is to be able to simulate various line faults while also providing a slightly safer environment for debugging.

Features

• Toggle Switches to break Hot, Neutral, Ground
• Polarity switch to swap Hot and Neutral
• Short Switch to short Neutral to Ground
• Indicator light showing voltage differential going to the outlet. This acts as an on/off indicator.  Also, if this light is on but the GFCI light is off then the GFCI breaker must be tripped.  This also helps you quickly find out if another breaker upstream has been tripped.
• GFCI Outlet.  With the toggle switches in nominal positions the GFCI outlet will provide additional safety when probing around my high voltage projects. Note: this GFCI outlet will not function properly when the toggles are configured for a fault condition.
• I like to keep one of my outlet testers plugged in to show the line configuration.

 Pictures of the Build

An Old-Work Junction Box is the enclosure

Right Toggle Switches

Left Toggle Switches

Stuffing it all together

Other Accessories

Here are a few other DIY accessories I use with my Bad Power Source. 

NEMA 5-15 Plug to Banana Jacks

Split-Rail Extension Cable for Current Monitoring

My Full Test Bench

Connected in the following order:

1. Bench Power (Conditioned, surge protected, breaker)
2. Bad Power Source
3. Variable Transformer with 3way outlet for voltage monitoring.
4. Split-Rail Extension Cable with current meter
5. Device Under Test. (I used a lamp in this picture)

Complete Bad Power Test Bench

Future Ideas

• Add a Hot to Ground polarity toggle switch.
• Add an indicator lights before the hot switch to indicate incoming line voltage.
• Full isolation transformer so it is safe to probe with my oscilloscope.
• Step up transformer for 220V verification.

USB Charger Assembly

Solder Paste Stencil

The Solder Paste Stencil came from OSH Stencils.  It was pretty easy to use, but the blue tape didn’t really hold it tight against the board so i got a bit of solder paste bleeding outside the pad boundary.

Reflowing on my Mother’s hotplate

Almost all parts have reflowed

Completed board with through hole jacks installed

Remote Control Panel

I created this wired projector remote panel for my church to make it easier to control the projectors.  No longer must we struggle to configure the projectors by waving around the IR Remote.

I installed a cat5 cable that breaks out 1 twisted pair at each of the projectors.  All 3 projectors share a common ground..

The white box on the left is a Keystone jack box with an RJ45 keystone jack installed.  Each remote has a 1/8mini jack that is terminated to one of the pairs of the RJ45 keystone jack.

As finishing touch, the remotes are mounted on a board that I wrapped in some black felt that was left over from building my sound rack.

In the future I would like to figure out the signaling used by each of the remotes and create my own custom controller.  This would let me perform actions like freeze and blank to all 3 projectors simultaneously similar to what  you would get from a video switcher.

Projector Remote Panel