Here is the power supply you need.
Small in size and can be used without the Carnetix powers supply and they output up to 3 amps.
I will be installing two of these in a small project box for a total of up to 6 amps output.
Then use two of these.
To hook them up take it to your local Radio Shack and buy the correct plug to fit in the power input hole. from that make you self a power wire.
Now you are all set and have 8 powered USB, that will power just about anything you could put on it.
I have to agree I am using 7805s to power my hubs actually I had a couple directly powering a couple of stubborn usb devices in my last car
Originally Posted by colin
12v-powered 7-port hub? Where do I sign up?
I tried to cobble one together from a regular 7-port hub and a 2-amp USB-like charger, but the combination failed. So yeah, I want one. Bad.
Why not implement an LM (eg LM7805) based Voltage regulator to create a regulated 5v DC out (handfull of components) and use a regular 'Ritmo' style 7 port hub that takes an external 5v plugpack? Really not that tricky...
Its been a while but an LM7805 can pump out 3A quite comfortably. The fact that we have a flat full DC wave to begin with makes life even easier...
Check this out... I doubt this would cost more than $2 to make.
What's wrong with this? They make a 4 port and 8 port model as well.
While 7805 looks cheaper and easy to implement, being a linear regulator, it is notoriously inefficient. It would be a very bad choice to put into design/production especially in a CarPC environment.
Originally Posted by VYSSO3
Consider 1A loading per port, each 7805 will dissipate around 7 Watts at 12V I/P. Multiply that by the number of ports and you easily have a furnace inside your car...lol. They need loads of heat sinking as well...In short, that is too much power wasted for nothing. IMO, you should be looking at nothing less than a switching regulator. Linear regulators like 7805 are so last century.
Another point to note is that most well engineered USB hubs control the 5V VBUS line on each port individually.They call it PPPC (Per Port Power Control) and has obvious advantages. So it is not just as simple as jacking up the amperage on each output.
Sure, they're inefficient, but they're cheap, easy to install, and they'll work. Just heat sink them. You're unlikely to be loading 1 amp per port, so that's a worst case situation.
A switching regulator is more elegant, of course, and if you just have to have one, mp3car sells a point of load regulator for about $35 from Opus or a similar one that you can add on to a Carnetix P1900 or 2140.
Another point to mention is switching OFF of the hub.
It needs to switch off with the PC and not with the car, otherwise the PC throws up USB errors as it is still running and the hub gets switched off by the car.
Not a problem at switch on as the PC starts later than the car and the hub has to wait for the PC.
Most hubs can be powered off the ciglighter, but alot of adapters dont hit 5V, and the ones that do only have a small amprage. Some people have stated that a HUB will run perfectly on 4.5V, but I really dont trust that. I dont trust the inveter method either, as I tried it and went through almost 5 or 6 hubs. The best thing to do is simply buy a 15W PSU from OPUS that can handle 3 hubs as long as their all 1 AMP per hub. In my setup I have one 7 port hub at 2 amps, then the SOHO echo cancel card. Maybe you should focus oin making a cheap power adapter that is true 5V, that way people can go with a hub they trust and have more variety. I think if you can come up with a regulated 5V adapter with at least 3 or 4 amps, that would be awesome.
Originally Posted by Lok
Sounds like a good deal untill i read thru the actual specs and and then there is a 500 mA limit to each port. Each of the three WD Passport Drive i have will take 1000ma (twice what each port is regulated to.
Originally Posted by Dougw133
And for that price i could do better with what i suggested in my earlier post.