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kevin g 07-28-2012 08:38 AM

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. :evil

GS Addict 07-28-2012 08:45 AM

Great job!

LaurelPerryOnLand 07-28-2012 09:04 AM

Congrats...nice work.
Geez...this is exactly HOW small businesses get started.

Did this in the garage?

Available as a kit? When?

Think others might want.

hardpackrider 07-28-2012 10:49 AM

+1 on the kit.. :-)

really great install. I've the fuse block.. still sitting in electro wrapper..(saving for GPS), but for those of us with limited electrical kno-how.. this looks like magic. :-) great work, thanks for posting.

Sent from my iPhone using Tapatalk

Poolside 07-29-2012 06:52 PM


Originally Posted by kevin g (Post 19232549)

Nice job, Kevin! You look like you're an old hand at this. Is that a digital amp and a microcontroller on the audio side?


Originally Posted by kevin g (Post 19232549)

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

Seems normal to me! :lol3


kevin g 07-30-2012 05:32 PM

No Microcontroller Used
There is no microcontroller in the amp. The larger chip is a volume/balance control chip that is commanded up/down by grounding a pin. There is 2dB volume change per click and is slews quickly if held down. The balance feature is not used and the chip always starts in balanced mode.

The amplifier has adjustable gain and an internal charge pump so it generates its own negative voltage so the output has zero DC offset and no large capacitors are needed on the output to keep things small. Both chips are made by Maxim.

Poolside 07-30-2012 06:32 PM

<BR>Cool. I've seen that Maxim volume/balance part, but not the amplifier. I just had a look, their DirectDrive setup is a pretty nice deal. Good choice!


JayhawkGSA 08-20-2012 10:36 PM

Nice work. I am wanting to do SOME of this and was actually just looking through Digikey for a weatherproof USB solution. I think I found the same one you have.

Any chance of you posting the Eagle file for your PCB?

DrogoNevets 08-21-2012 06:15 AM

the USB power on/off switch, where did you get it from?

Unstable Rider 08-21-2012 06:35 AM

Glad you are on our side!


srpuywa 08-21-2012 06:55 AM

I'm sure I could break it!

genka 08-21-2012 07:01 AM

Excellent work! Unfortunately creating useful home made electronics is a dying art.

Epictetus70 10-05-2012 10:51 AM

:rickySimply awesome:ricky Clean and very creative. If you made a kit, I'd buy it. :beer

SpEd 10-07-2012 09:44 AM

Amopther alternative
I wish I had the know-how to create what Kevin did and I'm certainly not making light of the op's solution, but I think I might lose a limb if I tried to do something like he did. :clap

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