Introduction: Pocket USB Emergency Charger

About: Electronics hobbyist and a DIYer and i love doing this stuff.

I been able to make a Pocket Emergency Charger compatible for smartphones and other USB compliant devices out of salvaging an electronic pcb from an old cd player.,Since the famous LM 7805 Linear Regulator i found was the main component used to built a charger.i have seen various instructable project in various form here too.,So i must do a different design among others.

Objective: for emergency use only(while away from a wall socket ),for charging USB compliant device when they run out of juice as your powerbank runs out of juice too.Buying a spare 9 volt battery would be the best remedy that can be access in stores nearest to you.

*Steps and how i made it were all explained here.

Step 1: Materials and Tools Needed

1. LM 7805 (salvaged from old cd player)

2. 3 Resistors 100 ohm (salvaged from old cd player)

3. Heat sink (salvaged from old cd player)OPTIONAL ONLY

4. Some Wires

5. SPST switch

6. Flexiglass 2.5 mm thickness( i used scrap only)

7. 9 volt battery(6F-22)

8. 9 volt battery adapter (from an old 9v battery)

9. LED ( any color)

10. USB-A Female

11. PCB


Soldering Iron (30w)

Soldering Lead

Analog Multitester ( i don't have Digital Multimeter yet)

Helping Hand (optional)

Ruler,Pencil,scratch pad paper( i used old bond paper with print on it)

Scoring Blade( use for cutting Flexiglass)

Vinyl tile (i used scrap only)

Quick Dry Epoxy (mighty bond)

Elmers glue( optional for patching gaps)

Step 2: Building the PCB

Soldering all the components needed together were quite and simple to follow as the schematics in image form explains it all.I just added 2 resistors to the D+ and D- terminals of the USB as apple products won't recognized it without those two resistors.

Step 3: Preparing the Bezel

The funnest part and the most challenging in doing this project is the "Cutting"...So i must do a simple draft (plan) to fit all the components inside it and to see how big or small it would end up eventually.Using a thinner size flexiglass would make it smaller(around 5mm smaller than this)..I suggest using 1-1.5 mm flexiglass commonly found on a used transparent cd case is the practical way of building the bezel.And it gets more fun when i get confused with the battery dimensions found in googling only..So i rush myself to purchase an Extra Heavy Duty 6F-22 Battery made of carbon zinc,i can't find an Alkaline at the time of buying it in store.Then i measured it manually to get the most accurate measurement for my project.The image attached of 9V battery dimension are from different battery manufacturers.Which were all different from each other and to the battery i bought..And i found it confusing.

Step 4: Assembly

After several minnutes of cutting ang scraping,it's time to assemble it with the pcb chip inside.So after fitting and applying some adjustment of the flexiglass through scraping using exacto knife.,I glued first the front and rear part of the bezel,then the left and right part of the bezel followed it,And finally soldered the 9volt battery adapter on it's extended base.As seen on image,i put some holes on the bezel itself,three holes on each side and one underneath the base,hoping it would help the heatsink to cooldown itself when it heats up gained by LM 7805..

Step 5: Test and More Test

Run a test first on multitester not directly on any device,so if any problem and there is a short circuit,it wont hurt your device.And i did some errors on my first test,i found that the LM 7805 isn't working ,the multitester dc voltage result still showed me 9.2 volts DC,i wonder why,.,so i dismantled the left side of the bezel to check what's wrong..And i found what causing the LM 7805 did not work-the resistor soldered on the (D-) terminal is shorting with the Positive Input of the LM 7805,luckily the LM 7805 did not die easily after it shorted.And fix it immediately..And put some insulation that caused it,and run the test again..Finally,achieved the 5.1vdc required for charging USB devices.

Step 6: Paint Job

Spray painting it is just an option,but i still have left over of spray paint lying on my craft table..So i finished it with metallic black spray paint again.Patching or masking the USB and LED indicator part and the 9 volt battery adapter area.

Step 7: Result

Then another project was done out of salvaging electronic parts and using scrapped materials.That would be added to my DIY collection that i can used in times of need.

To anyone who is interested in doing this type of project,instead of using a common 9 volt Carbon Zinc battery

i suggest choosing the right 9 volt battery will be helpful ,as it will prolong charging time on your the image shows types of 9 volt battery with their corresponding specs.

So there it goes again.,hoping you enjoyed reading it,and hoping to help someone who wants to build something like these,or just used the common and famous use of Altoid's tin case for casing and easy set up.The black tin case shown in image is used for storing my AA rechargeable batteries.

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