Visual Field Augmentation - 2nd Generation

Visual Field Augmentation

2nd Generation Device - Virtual Vision Sport - Wiring

No preamble, lets get into it!

This is the faulty connector cut from the headgears cable, I've stripped back the plastic to see the colouring of the wires, and will use an ohm meter to cross-reference the individual wires back to the terms that I got from the base unit with the oscilloscope.

I included a penny as a reference to illustrate the size of the wires and what we're in for.

Note: the pin-out numbering is reversed as this cable mates to a female connector. To this day I'll wire 2 or 3 female jacks flip to a male jack and wire it completely backwards... so use caution when determining male/female orientation (cabling or otherwise...)

The meter sourced out all lines and I checked the key lines, Composite, Voltage, Grnd and Back lit twice to be sure.

Rather than hardwire the power and video signals to the display, I thought that a quick connect may be useful as I intend to experiment with as many cameras as possible. So I scrounged through my junk pile and came across this perfectly useable Sound Card/14.4K Modem Combo. With a hacksaw the connector assembly was summarily removed with a spare Phone jack.

All Connections were checked with an ohm meter to ensure that they were isolated from each other. There is a common ground on the outer ring, otherwise all others are electrically isolated. All of the jacks are 1/8th" stereo jacks for which I have the male cables in abundance. (dead walkman head sets, computer speakers etc...)

This is a typical right angle 1/8th" stereo jack, the shield can act as either ground to suppress noise or as in this picture simply as a 3rd conductor.

The close-up shots are a touch jagged, but fair, considering the 14X optical zoom on the Video camera is at the max and has to be manually focused.

This diagram is to illustrate, the wiring used, and may very well aid me in debugging, should things go wrong... It does tend to slow things down considerably to have to document such tedious details, but they are so darn handy when grief arises, and things get complex quickly on these sorts of projects.

I opted to keep the video signal separate from the ground as it appeared that way when I scoped out the wave forms. Though it can easily be soldered over one pine if no display is visible.

I had a spare jack and figured that the audio may be a nice touch if this thing actually flies.

The telco jack was yanked to make way for a crude brightness control for the back-lit on the display. When I say crude it is literally a resistive voltage divider. I used the largest mini-pot I had on hand 20K and wired in a fixed resistor to drop approx 1 Volt from the top to keep from baking the Back-lit by exceeding 4 VDC.

The R divider is 20K plus a 4.7K in series totaling 24.7K across 5VDC causing a total current draw of 0.202mA, (using Ohms law) but the Back-lit element will have a internal resistance that will lower the R and increase the current. As I'm not an engineer, it's real late, and I can't think of another solution this will have to do... Again bear in mind that I'm connected to the grid, and just testing, when things get wireless, and portability of power becomes a consideration, excuses will have to be replaced with solutions.

As per usual, I'm more than pleased with myself and find that this is as elegant a solution as can be expected for a few hours effort. Once tested to ensure that all terms are soldered to the correct points, A judicious slathering of hot glue will hold the wires in place and a mini box will have to be fabricated to make it more robust and save pieces from experiencing any shorts.

The stakes are high with real money riding on this, so I don't dare power it up until I've had a chance to sleep and review my work with a clear mind.

Comments or Suggestions

mailto:frnkgmbk@renfrew.net

Back to Visual Field Augmentation