usb in car

PLEASE HELP. i am trying to find a way to install some usb ports in my car to be used as power supplies for various devices (mp3, nav systm,phone).  i hate clutter, so i'm trying to stay away from adapters for the cigarette lighter plug.  im pretty sure i need to reuce the volts and amps so i do not harm the devices.  please help. i dont even know where to begin.

Topic by lvlaveryk   |  last reply


Having a peculiar issue with the max6675 and grounds?

So first off, this is an application for use in a car. I have ensured that all of my grounds are good, and the power is clean, so I know these are not the issue, at least not on the car side of things. I am trying to get an electric fan controlled by an atmega328 (through a relay), which I have successfully achieved  on bench tests using an alternative heat source. It works reliably until I apply the circuit in the car. When I install it in the car with my thermocouple on the radiator pipe for the temperature reference I get all sorts of temperatures that are not the correct one. Its either very high, or very low. I have tried multiple thermocouples (of similar style) with no changes. If my thermocouple is not making contact with any grounded portion of the car (for example, the engine) it reads fine, so I know that my issue lies somewhere in there. An easy solution would be to simply mount the sensor in a coupler in the radiator hose (thus isolating it as best as I can) but I would rather fix the issue than apply a bandaid. I've tried searching for other people having a similar issue but haven't had any luck. One peculiar thing to note is that if I have the ground disconnected, and the thermocouple touching a ground, the system receives power, so I am assuming that the junction makes contact with the outer case of the thermocouple. My circuit is nothing too elaborate (I can upload a schematic if need be); I have a DC/DC adjustable converter to get 5v for the micro and 6675 power, which does not have an isolated ground, an atmega328, an OLED display, some tact buttons, and a max6675 development board. There are other passives as well but those should be minor. Does anyone have any idea what may be going on with this? I'm stumped. I should be able to provide any info you may need.  PS: this is the development board and thermocouple that I am using: http://m.ebay.ca/itm/New-MAX6675-Module-K-Type-Thermocouple-Thermocouple-Sensor-For-Arduino-Hot-/151324177617?nav=SEARCH 

Question by zack247   |  last reply


Powering an Android Tablet without a battery?

So I bought my sister this Visual Land tablet about 2 years ago. Eventually both the mini usb and charging port broke off from the logic board as expected from a cheap product. So I have this nice idea of using the tablet as a car nav/entertainment system. simply get rid of the battery and push 5v via a standard cigarette light usb adapter or make one with some 5v regulators and done. I tried resoldering the charge port. I get 5.23v on random points on the board but I get 0v at the battery with the charging port connected. I pulled the battery and tested the terminals on the board with the charging port connected no battery, 0v at the board and the battery alone is also 0v most likely dead and trash as it sat for 1.5 years in a shoebox untouched. So I pulled out my homebuilt psu power supply and hooked up the variable output to the battery terminal on the logic board. When pushing 3.7v~ I can get the first splash screen to show up but the tablet shuts off right after. When pushing 3.8v any thing higher the first two splash screens show and android starts to boot but the tablet powers off soon after.. So i decided to risk it and pushed 5v directly to the board. It started up fine and booted into android normally except for the low battery issue and some heat coming from the processor. Maybe a heatsink and rigged laptop fan into the casing could fix that? It shut off normally as if it had a dead battery. How much voltage doeas a generic android board need? Current?Does the board take 3.7v but since theres no battery it wont boot? How could I fake a fully charged battery? Or could I possibly flash a custom rom? Do you guys need more info? I could provide more pics Note that the battery is a 3.7v 3500mah li-ion battery with only a positive and negative hookups. Also i took some tape and covering off the battery to see if it possibly had its own controller board. It did have a small  pcb board but it seems that its only "a transfer" board, it takes the power from this cloth like cable and passes it into the wire thru the pcb. Should I try to hookup 5v straight to the battery to test it out? Battery has 0v so it might be useless.

Question by mcarrascoza   |  last reply


USB GPS module tracking with custom application? Answered

I am working on getting some data acquisition integrated with a mini Baja car we're working on, and I would like to be able to track position with GPS, and hopefully speed too, but thats secondary to trying to track position. I'm going to mount a tablet netbook in the dash of the vehicle; can I use a USB GPS module, something like this:  http://www.newegg.com/Product/Product.aspx?Item=58-179-009&SortField;=0&SummaryType;=0&Pagesize;=10&PurchaseMark;=&SelectedRating;=-1&VideoOnlyMark;=False&VendorMark;=&IsFeedbackTab;=true&Page;=2#scrollFullInfo My main concern is it looks like these are made to work as Sat Navs with Microsoft Streets and Trips.  Instead, is there a way to just obtain the position data directly with custom software and record it either as a spreadsheet or graph, or even just something like a comma separated text file? I don't know anything about programming, so I will be finding a programmer to help me out, but I was wondering if this is the best way to go about this or are there gps modules made for this type of application? Thanks!

Question by capt. untsahts   |  last reply