Portable Power Supply and Phone Charger [Video Added]

I've recently started to try my hands in the world of DIY, while trying different circuits I felt a need to have a variable power supply. Being a frugal guy that I am I built one for myself. This power supply uses an old lithium ion phone battery as a source and a voltage boost module to get the desired voltage for the circuits.

This power supply can also be used to charge your phone in case of emergency.

Step 1: Procuring the Parts Required.

The list of materials:

1. TP4056 battery charger. This one. I used specifically because it also has protection circuit built in.
2. DC - DC Boost converter.I used this one. It will be used to boost the voltage from 3.7v upto 35v.
3. 2 nos 9 volt battery clips.
4. An old cellphone battery or you can use this too.
5. A charger doctor or a multi-meter.
6. A USB female port.
7. A small plastic box to put things together.

Step 2: Build.

1. I started by soldering one of the battery clips to the battery terminals. Red wire to +ve terminal of the battery and black wire to -ve.
2. The second battery clip has to be soldered in reverse to the charger module i.e. black wire to the +ve(inner terminal) and red to -ve(inner terminal as well). The battery can be connected directly to the charger but I used battery clips to easily swap batteries.
3. Put the circuit together according to the schematic shown(pic 3).
4. Put it all together in a box and glue the modules with hot glue.
5. Use a soldering iron to cut out for the two ports.

The potentiometer on the boost converter is used to set the desired output voltage.

This Power bank can be used to charge your phone as well :)