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Old 07-28-2012, 08:38 AM   #1
kevin g OP
Adventurer
 
Joined: Dec 2010
Location: San Diego
Oddometer: 95
Custom Electronics Installation

Now that I have had my 2011 GSA for a while I am starting figure out what I want to add. For travel I need a USB charging capability and I wanted a better amplifier for my helmet speakers. I have 30+ years of military electronics engineering so I decided to make my own. Here goes:


The circuitry is housed in the 2.2"x3.2" box mounted on my TT dashboard. The USB port is up on the left in place of the cigarette lighter socket with a water-tight cap and on/off switch that is IP67 (dust tight and splash tight). The 3.5mm audio input is on the box along with the amplifier on/off and an idiot light that is on when either circuit is powered. The USB port will be active when the bike is off and the audio only when running. The 12V socket is fused with 10 amps. My mini compressor draws about 7 amps peak so this should be plenty. Here is the circuit:

The USB port uses a switching power supply for best efficiency; my phone draws 0.25 amps when charging and my MP3 about 0.2 amps, from the 14V. The audio amp uses a linear regulator so that there is no potential noise that a switching supply might put on the audio.

The amplifier has a volume control that is a click up or down, or slews quickly when held. The output power is about 130mW and will blow your ears apart with my Torx Pro speakers. Great speakers by the way if you are wondering. I always wear ear plugs for the wind noise so I wanted enough power from the amp. The audio draws 60mA at full volume from 14 volts.

I wanted to place the volume control at my left hand so decided inside the hand guard would be a sweet place. I taught myself to make a mold and lay up this nifty carbon fiber switch pod:

The switch is an industrial IP67 click up/down variety. I mounted it in the hand guard using industrial sticky-back Velcro.

The audio output I want somewhere around my left knee. My original idea of tucking it under the edge of the black trim piece has not worked so I have this temporary mount that does the trick.

Eventually I will hit on a better way to mount this. I think it will involve some more carbon fiber in a little pod but the vision has not hit me yet. If anyone has a suggestion I would love to hear it.

All of this is powered through a Fuze Block. I do not like the idea of installing the block under the seat so I did some poking around and found a great place at the back of the beak just under the spot where the auxiliary power outlet mounts. I fashioned a mounting plate from aluminum and used an existing screw and one Adel clamp to hold the plate. After painting the plate satin black it looks like it belongs there.

There is plenty of clearance to the fork leg at full lock and I like the hidden installation. This location does not seem to get as dirty as under the seat so I am not too worried about the environment. Here it is from the top.


So far I am pretty happy with these additions with the exception of the audio output, but it will come to me eventually. The switches and USB connector where samples I got from vendors and are not cheap. The mil spec toggle switch would cost about $100 so if I had to buy a switch I would get an industrial grade instead. The USB switch is about a $25 and would also be great for the audio. The volume switch has an really cool feel and would run about $45 but I just had to find a use for it and it was the inspiration for this whole project.

My friend joked about "leave it to you to design a system around a switch". That's what I did.
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