You always run out of battery while outside and forgot your charger, ain't it? or you have a charger but do not have any plug point nearby..faced it ,right? So I will be talking of about the solution of this problem. Here I made this 5V regulator out of the 7805 IC. This IC can supply 5V from any input of 7-20V. Here I made a soldered board. I made 2 type of onnectors for the input.You can extend it to any number of connectors as per your requirement and availability.But you must include the 9V connector. Same goes for output. But make sure you have connected the female USB connected, so that you can connect the USB cable and connect it to your cell phone.You can add more output connectors as required. Now you must take a 9V battery and keep in your bag, this battery will be your power provider.This battery has to be connected as the input. Buy one good 9V and keep in your bag.Now talking about the circuit ,the IC simply converts 7-20V input to regulated 5V output.The two capacitors at the two ends simply reduce voltage spikes and give smooth output. So no need of any expensive powerbank.you can also charge your phone using solar as input. Not only phone, you can also charge any USB device,or power up any 5V circuit with this.Include a heatsink for the 7805 ,as the device heats up for inputs of high current. The maximum cost can be 1.5-2 dollars.So go ahead and build!!!
Step 1: Parts List
1 7805 IC along with heatsink and nut bolt
2 100uF capacitor 1piece
3 10uF capacitor 1 piece
4 USB female connector
5 breadboard soldering board and solder and iron
7 9 Volt connector and battery
9 other connectors if required
Step 2: Connecting and Testing on Breadboard
At first build the circuit on breadboard and test with a multimeter. If 5V output not coming,rebuild it again.
Step 3: Soldering
After 1st step is successful, solder the components on perfboard and take the 9v connector and solder it and the female USB at the output. Don't forget to add this 2 components. Also short the middle two data pins of the female USB.Keep the schematic beside your soldering station.
Step 4: Finally Testing After Soldering
Now after the soldering is complete, test the circuit again with a multimeter. Also connect your phone to see whether it's charging or not.Add a heat sink for the 7805. So you are done after all.