Thursday, November 2, 2017

mini love - part 31

Patience pays. I have systematically assembling the components to configure a A/V recording system for used with Harry's Laptimer. I want to get the best deals possible and so far I managed quite well. Most of the pieces were procured from Amazon when I spot the prices dips. Sometimes the difference is over 50%, like the case of the PLX Kiwi 3 bluetooth ODB dongle.

the Kiwi 3 ODB dongle arrived

also arrived is the 6-inch long RAM Mount arm

this is what the GoPro camera mount looks like with the extra long arm

this is with the standard arm

with long arm

with the standard arm

The longer arm just place the camera more inboard so it is less likely to be obscured with a passenger. The truth is the standard arm would most likely just fine, but I want to have a longer arm. All my RAM Mount, except the phone model specific cradles have been used and reused in different mount configurations.

Update - USB-C cable:

I didn't want to order everything that I envisioned all at once. Some of these parts can only be best specified once other pieces are firmed up. The cables falls into this category, even now I am still unable to firm up how best to handle the Sony microphone. I don't want to waste money buying extra cables that I would not use.

The latest to arrive is a 6-foot USB-C to USB-A cable. This is for providing constant power to the GoPro camera from the rear 12V outlet. This location is chosen to keep the cockpit free of clutter, and to leave the two 5V ports up front for the iPhone and another device like the GPS sensor.

I chose this Amazon Basics cable as it is USB-IF certified

6-foot is just perfect

no extra slack at all by the time it reaches the 12V outlet where a 5V adapter will be inserted

this polyurethane bushing kit is for the front control arm; this is a stiffer racing version offered by Powerflex; it will be a very labor intensive installation which I am not looking forward to

I am still undecided yet as how best to set up the Sony mic so it hangs just off the boot door. Ideally the best location for it is under the licence plate light bracket. That will require extra 6 feet or more with the microphone cable length as it needs to be brought up to the hatch door hinge and down to the license plate light assembly. The other consideration involves the microphone is the Pro 3.5mm mic adapter.

I do not like the Pro 3.5mm mic adapter hanging off the GoPro camera. The only way to do that is to buy a USB-C extension cable and hope the high serial communication is not compromised. I can only find 1 meter long of these extension cables. I infer it is to keep maintain signal integrity so most devices would still work.

1 meter long USB-C extension cable

The problem with 1 meter long extension cable is it only reaches the bottom cushion of the rear seats which will where the Pro 3.5mm mic adapter have to rest. It is only marginally better than leaving the adapter hanging off the camera.

Update - still more update:
Just a bit more tiny progress on the GoPro setup.

To recap what started my GoPro headrest mount project. I wanted a vantage point that will capture the driver, the instruments, and most important the track. Of all the mounts I found in my research I like the BMW/MINI headrest mount the best. The most compelling features is it is modular, and safe in a crash. The major down side is the ridiculous high price. It consists of two parts that you need to buy. I knew that I can do better in designing my own.

the BMW/MINI headrest GoPro camera mount

it is modular, and designed for ease of removal - can my design achieve this? you bet

here is a nominal cost after discount

I hunted for my countless number of 5V adapter for 12V automotive outlets. Because of I own so many vehicles they are scattered. I don't care to waste money for brand name adapter like the Belkin sold at Apple Stores for $25 apiece. They cost less then $0.30 USD to make.

First I need to test if my older 2.3A adapter are up to the job for GoPro. This is one crap adapter that I have aplenty. While electrically it works fine, the deadly sin of the design is it works itself loose.

The only ones that I have that I found satisfactory is the "shorty". It is identically electrically to the green one on the left, but with stronger springs to keep the adapter from working loose. I got it from a 12V receptacle that I bought for another project, and it costed around $3 with the receptacle.

defective design (left), and the "shorty" adapters that works

just a photo of the GoPro charging - the red indicator illuminates

the "shorty" adapter is nice as it sits almost flush with the 12V outlet; for track condition, I would add a piece of 3M blue tape to further secure it

this is what the Sony stereo microphone looks like without the extension cable


  1. I wonder if vibration will be an image issue with the longer arm. It all depends on the resonant frequencies in the car, but I would wager that there will be a difference between the long arm and the short arm. It's probably more of an issue on motorcycles, though.

  2. Even long before I decided to explore mounting onto the seatback, I considered these issues. From using the iPhone as the camera you are exactly right about the nature of the frequencies. Most surprising is when mounted on a RAM Mount arm the video quality is better than mounting same but let the phone also supported by the dashboard to make the mount more rigid - restrict the vertical soft bounce.

    I expect the long arm would just be fine with the GoPro which unlike the iPhone 6S plus that has optical image stabilization. It uses software based digital stabilization, which can handles high frequency vibrations much batter. I also think GoPro handles the entire frame, and iPhone progresses progressively scanned lines. GoPro is designed for action sports but not most smartphones.

    The proof of the pudding is testing out on the track.