# 3,7v Emergency Charger Nokia Cellular With 9v Battery

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## Introduction: 3,7v Emergency Charger Nokia Cellular With 9v Battery

Hello to all. I wanted to propose to you a simple cellular charger with technology of low level that however works and carries out its task perfectly. Draft of a cellular charge of emergency that can be indispensable if it is found to us with the batteries is down and without a station of charge to hand capacity that is in all those unforeseeable situations that before or after can happen.

## Step 1: The Components

The circuit is much simple one and comprises besides the battery of 9v a made reducer of tension of approximately 2v from 4 diode valves 1n4007, in series to a resistance PTC, member that I have extracted directly from a local p0wer source of cellular from 3,7v that it must have a function to stabilize the tension and to make to limit the current in case too much absorption.

## Step 2: On Air

All the components have been knit in air between they and their time connected to the cable and to the feeding thorn.

## Step 3: The Assy

Here all together before being opportunely isolated and encapsulated in the container;

## Step 4: The Fuse

As last thing I have connected a fuse in series in order to prevent dangers in case short-circuit. The fuse from put me is of 100ma but this valor is approximate.
I have maintained this value for emergency low.

## Step 5: The Video Charge

In the short video it can be seen as my local power source works to the perfection.

## Step 6: Conclusions

This job has been simple to execute but useful for the application to which it is lend. I hope to have helped someone with this explanation! Salutes and to the next one on these pages.

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## Questions

what will be the output voltage? and how long a 9v battery can charge a cell phone?

2 replies

This realization was a few years ago: what I can tell, from what I remember (in that the object is no longer in operation) is that the voltage across the cell's power plug was about 7v.In fact, for each diode there is a fall of 0 .5V. I found the successive approximations and approaching as close as possible to the original power supply voltage; as regards the 9v battery life, I have never tried the maximum charging time but I can tell you that once I used it for emergencies, and lasted for more than an hour with no signs of abating and charging the phone.
Thanks for the comment.Torx

a usual phone charges at the voltage of 3.7 to 5v. can i reduce the output voltage by adding 5 or more in4007 diodes? or is it better to use a resistor? if i can use a resisiror, what will be the ohms ?
thenks for your reply. i here at india, power cuts are usual. it will be useful for me if i can build a better one.

Thanks, but we would welcome a schematic drawing with all items labeled .. eg i dont know what a PTC is either .. the picture SEEMS to be a very small capacitor .

Positive temperature co efficient

"Positive Temperature Coefficient (PTC) thermistors are thermally sensitive semiconductor resistors which exhibit an increase in resistance at a specified temperature. Change in the resistance of a PTC thermistor can be brought about either by a change in the ambient temperature or internally by self heating resulting from current flowing through the device"

http://www.educypedia.be/electronics/resistorsnon.htm

What is the value of the capacitor used?   Is it a 22nF capacitor?

It is not a capacitor but it is a resistor ptc.
I don't know much about it. I found at the Interior of the PSU 3 .7V and its value for ohm is approximately 1 ohm.
Thank you for the question , you are interested in the realization of the project?

... is that fuse exactly 100ma?...where can i buy this fuse?.. thanks

Sorry if I sound daft, but... Why are four diodes used? Would one be enough? Also, does the absorption limiter need to be connected directly to the feeding thorn? Or does it go between the cable and a diode? We are good to be spitting pretty colors! V-Man737

2 replies

The diodes 1n4007 are in series in order to obtain a voltage drop of approximately 2v, in order arriving to approximately 7v that it is the tension not stabilized that I have found on the heads of the local power source 3,7v of the nokia. Resistor PTC was in series to the feeding to the inside of the same local power source. In other words I have recreated the conditions (approximately) that there are with the local p0wer source originates them. In phase experiments had tried they to diminish the tension in order to approach to me the declared ones 3,7v but telephones sends I the written one to me of the type " not possible charger"

That is good to know! I was not knowing diodes had voltage drop.

incrivellll

Thanks for the observation to Bersek87 !

the 1A fuse you put in there is not needed. a 9V battery isnt going to output anything close to 1A.