USB allows to share all kind of data on a small USB-Stick, on every PC. Even big amounts of data can be carried on an USB Hard drive. And it' s a perfekt power soure for mobile devices eg. cellphones or MP3-Players.
But soon you'll spot the first problems. You just haven't enough USB-Ports to charge all your moblie devices. Hard drives need to much power for some PC's, most stereo systems and all USB-OTG(on the go) devises. It's Impossible to charge Ipods with a normal USB charger.
I was annoyed of all these problems, so I thought about a solution. I came out with this USB-stick-sized adapter. It should help you with all your USB power problems.
Mainly it has 4 functions:
1. Charge two USB-devices at a single port, while one is still connected to your PC/ other host.
2. Charge two USB-devices with an external power supply.
3. Take power from an external power supply to be able to run USB hard drives on OTG devices, stereo systems, ...
4. Charge your Ipod (I haven't on so I can't tell you if it works). This may even help to charge your moblie phone faster, but try it at your own risk.
Make sure you read the Important Information below.
Step 1: Important InformationFIRST: I'M not resposible for any damage to you and any devices that this adapter is connected to.
Read through everything (especially read bold and underlined words/phrases) before you start. Steps in [ ] are not nesessary for some functions. You can skip these steps if you want.
For this projekt it is very importent to work exactly. Even tiny mistakes can cause big problems. Reminder that whenever you work with USB. (or do you want to blow up your mainboard / phone / anything else ?)
This isn't an USB-Hub, so dont say " the second port doesn't work for my USB-stick". The second port just offers power to charge devices.
If you want to run a hard drive at a OTG-device (in my case it's the S2) remeber it might just accept Fat32 which limits the size of one file to 4GB.
If you can check first if your hard drive runs with just power. Simply plug it into an USB charger and watch if the LED turns on or not. If the LED does't turn on (and your hard drive doesn't make the usual sounds) function 3 might not work.
I might have mixed up meanings of a few words (like port & socket) but I'm too lazy to correct it. That's it for now. Go on.
Step 2: Preparation: Blueprints
Function Nr. 1: We want to have one fully funktional USB-Port in any case. (power & data) So we have to connect the plug directly to one port. I figured out that too long traces (especially thoses which will be later used for the data) on the PCB cause problems. Have a look on step 7 to see how I did the PCB "layout". The second port needs just power so we can connect it to the + and - . So far so easy
Function Nr. 2: In combination with Nr.1 very easy as well. Just solder a USB plug (male) to + and minus or solder an external power supply directly to the circuitboard. It would work, but only untill you decide to plug in the USB plug we've added for Nr.1 ...
Function Nr. 3: ... If you would do so you got two at least slightly different voltages conected to each other, what mostly will cause overheating of one powersupplys until the voltage regulater burned out. So I had to find another solution. First I thought about an IC to regulate both voltages to exactly the same, but that would be too complex, too expensive and too easy to make huge mistakes.
I solved the problem with a switch inside the power connector. If you plug in the external power supply it will disconnect mechanically the power form the USB plug exchanging it with its own. That's a loss of 500mA, but who cares if you replace it with 2000mA.
Function Nr. 4: As you might know "normal" USB-chargers doesent work for ipod/iphone. That's because they "ask" the host controller before they take the power. I shouldn't mind because I haven't any products from apple, but I know many people would like a simple solution. On instructables I found this solution (http://www.instructables.com/id/Modify-a-cheap-USB-charger-to-feed-an-iPod-iPhone/) to charge iPod's / iPhones. In our case we would include the resistors to the second port which doesn't need the data lines. (step 10)
The final schematic is shown in the picture above. The circuit with included IPod charging function is shown in step 10.
Step 3: Preparation: Think About The Power You Need
So check your devices if you find information like "100mA". Sometimes you can have a look on the charger's output current eg. for cellphones. If you don't find any information, have a look on the List below.
Add the values of two devises which might be used together.
eg. 50mA + ~900mA = ~950mA
Note down your highes result.
Note: Some combinations only work with a PC, like any with the webcam.
Note2: The second port offers just power, so just connect devices to charge (or to use the power in a differen way eg. a USB-LED, a USB-Fan, ...).
Step 4: Preparation: Materials & Tools
"a large group of the people on this site don't understand exactly how electronics work" said XOIIO and he's maybe right. If you don't understand what is meant in the following paragraph and the reason why this projekt is nothing for you. (Serch for "regulated DC" if you still want to do this and inform yourself)
Missing knowlege can destroy your devices. I don't want to hear "blah blah blah you made me destroy my device" afterwards.
Let's come back to the power supply.
In the step before I told you to figure out how much power you need. 2A (2000mA) should be enough in (nearly) any case.
Make sure it's voltage is 5V (min. 4,65V - max. 5,25V) on every load (0,01A - 2A). To measure on differnt loads you can put a resistor between + and - ; eg. for a load of 1A you need a 5V /1A= 5Ohm . Keep in mind 5W (/10W) become heat so take a big resistor.
Where to get the stuff?
The simplest solution would be to buy everything from your favorite online store.
You can get (nearly) all parts for free by disableling old devices. You can get the USB stuff from a broken USB hub or any other USB device. I take the socket and power supply from a crappy digital picture frame I got for free.
Very common you get a USB Power supply with your phone, the dockingstation, ... But in this setup it doesn't fit to the power socket. If you want to use it read step 13.
Step 5: Preparation: Measurements
1. Unpluged: Measure wich pins ar connected (resistance = 0 +- a few Ohm). Note that down. (Name the connections 1 - 2 - 3)
2. Plug now the power supply in an measure the voltage between all pins. Not that down as well. (Use the same names with + and - )
3. Now comes the most difficult part (to explain as well...)
If everything is gone right you should have written down 4 numbers, one number twice(if not you may have the wrong type of socket). This connection has to be later directly connected to yor USB ports (female) (to the + or the - line, just as you measured before).
The other connection ( + / - ) has to be connected to the USB plug and the ports.
The last connection has to be connected to the USB plug as well, but to the other power line (to the not connected one before)
Remember the numbers and connections for later or write it down.
Step 6: [Construction: Make The USB Doubleport]
If you have just like me only single ports go on. I use SMD ones (because they were lieing around) but you can use the normal as well.
Step 7: Construction: Circuitboard
Now cut out your part. Don't try to saw between the lines, "sacrifice" another for better results. When you're done with this take a file and remove any sharp edges. If some copper at the edge (usually 1/4 of a line) is leftover, remove it with the file as well.
Try to place your parts again. Everything fits? Perfekt. If not, do some modifications.
If eg. the plug has too big conection wires of the case remove the part between two holes to create a bigger one.
Step 8: Construction: Solder The USB Stuff
First solder the USB plug to the circuit board including it's case. Now go on with the ports. Solder their case to the bord as well.
The last thing you have to do is to cut through a connection. Which one? In step 5 you shoud have figured out a direkt connection of the powerlins between the plug and the ports. Cut through the opposite one with the carpet knife.
Step 9: Construction: Add The Power Socket
Step 10: [Construction: Make it Ready For The iPod]
The solution is for the mysteries problem of non-charching devices is...
Sending exact voltages through the datalines. To get those 2 voltage dividers made of two resistors each are used. There are two ways to charge:
Before you start to solder, try out the adapter with other devices to make sure everything works fine.
Because the space is very limited, you should try to get the smalest parts as possible; betwenn + and D- and D+ and - you could even solder a tiny SMD resistor. The values you need are shown in the pictures above. When you go an measure in the next step mind that you connected + and - with resistores (that means different results).
I've never tried this so I can't say if it works!
Step 11: Final Touches: Measuring
If you find any problems, try to solve them.
Mind the resistors you might added to charge your IPod alter the results, so read step 3 and 4 instead of 1 and 2 if you included this feature.
1. Keep it unplugged. Just measure the USB Ports. (without IPod charging option)
2. Plug in the external power supply. Just measure the USB Ports. (without IPod charging option)
3. Keep it unplugged. Just measure the USB Ports. (with IPod charging option)
Resistences for D+/- are just for the upper USB port, the datalines of the other ports belong to "other"!
I took the values from (1.) fast charging for the calculation.
Step 12: [Final Touches: Make Hard Drive Ready For OTG]
Important: FAT32 has a size limit of 4GB per data so you might have to split up bigger data.
You will need a program to change NTFS to FAT32. I used "EASEUS Partition Master 9.1.0 Home Edition". This free program might be not the best but it is good enough for now.
NOTE: During the progress data can get lost. So backup everything before you start!!!
The process might take long when there's still data on your harddrive. If you made a backup delete the origional partition and create 2 new ones (much faster).
Have a look on the pictures as well.
Step 13: [Extra: Take Power from an USB Power Supply]
Step 14: Let it run!
Have fun and report your results, any occuring problems and your solution if you found one.
If you made a much better version of mine write your own instructable showing us the differences (When you publish it would be nice if you would inform me via PM).
If you spot somewhere a language mistake feel free to correct me. I'm still learning.
Don't forget to rate, comment and if you like this feel free to follow me or to share the link. This would help me a lot.