While a cell phone is incredibly convenient, without a charged battery it's just useless weight. If a storm causes a power outage in the area, I'm not looking for candles and flashlights—I'm figuring out how to charge my iPhone!
There are a few well-known options for charging your smartphone without help from the electric company, including charging cases, car chargers, power inverters, laptops, and more. However, something we all have readily available already is that old landline jack.
Corded phones don't need to be plugged into a power outlet; they actually get enough power to operate from the phone line itself. When the power goes out, land lines will still operate on their secondary source of power feeding from the telco. Meanwhile our cell phones will slowly drain and die. With this simple hack, you can put that old relic to good use and convert it into an emergency power supply for your smartphone.
You'll need a regular USB cable, your cell phone's USB charging cable, an available phone line, a phone cord, a voltage regulator, and a multimeter. The multimeter is used to check the voltage of the jack in question and the voltage regulator keeps the output at 5V. The regulator makes a simple circuit with the phone cord and USB cable to convert the phone signal into power that your phone can use. And take a look at the complete guide by Make's Jason Poel Smith over on Instructables to see the process step by step.
Get a lifetime subscription to VPN Unlimited for all your devices with a one-time purchase from the new Gadget Hacks Shop , and watch Hulu or Netflix without regional restrictions, increase security when browsing on public networks, and more. Yeah very true. When I went to Nigeria a few years ago, every house used a landline phone, while few even had cell phones. But within the next decade or so, I am sure the trend in the States will spread to places abroad. That means is for 5 volt output.
Let me know the Voltage regulator number for 12 Volt output? Then I hooked up various resistors to see what the output would be with different loads. I determined that the supply voltage isn't regulated. This means that the voltage changes depending on the resistance of the circuit that it is powering. After some calculating, I worked out that the base signal coming out of my phone jack pretty closely resembles a 52 Volt DC source with a ohm internal resistance.
But it is enough to charge a cell phone. We know that the phone needs 5 volts in order to charge. But we don't know how much current it draws or it's equivalent load resistance. So we can't charge the cellphone directly from the phone line. We need to use a voltage regulator to bring the output of the phone line down to 5 volts and keep it there.
A LM 5 volt regulator should work fine. To make this simple phone line adapter you will need the phone cord that we have been working with, the 5V voltage regulator and a USB connector cable with a female end. Just connect the red wire from the phone line to the first lead on the regulator and connect the green wire from the phone line to the second lead.
Then connect the black wire from the USB cable to the second lead on the regulator and connect the red wire from the USB cable to the third lead on the regulator.
If you can't solder the wires together because the power is out , you can just wrap the wires around each lead. If you do this, you should bend the leads of the regulator away from each other. This will help you avoid accidentally crossing the wires. This simple regulator circuit is able to safely convert the base phone signal into something that can be used to charge your phone.
However, many voltage regulators are not able to handle the AC signal that they would receive if the phone rang. So if you are worried that you might receive a call while your regulator is hooked up to the phone line , then you may wish to add a diode between the red wire from the phone line and the first pin on the voltage regulator. This will protect your circuit from problems that may be caused by reverse polarity.
A regulator will work if you need an output of 5 volts but other kinds of voltage of voltage regulators are also available. In addition to these fixed value regulators, there are also variable regulators that let you set the voltage level with the use of a few external components.
One such variable voltage regulator is the LM These are what you would use if you needed a different output voltage. Plug the phone cord into the nearest phone jack. Then plug your phone and charging cable into the USB cable. Your phone should begin charging. In a few minutes, your phone should have enough power to make a call. Hello, really interesting article. I noticed that you mentioned a "Voltage Regulator".
What are the basic principles that article seems to be a little to complicated for me to understand. Any help would be awesome! Reply 6 months ago. The most basic USB standard is for ma so you should get one that accepts something like v with at least ma output.
You provide power to two legs of the chip, and you get a 5v output on the other leg of the chip. Ground is shared between the input and output. Too bad doing this in the US is illegal. Better make damn sure its a bonefied emergency otherwise you'll be charged with theft and interference with communications systems Reply 5 years ago.
You're such a genius. Whether this works or not, I'm going to build this just to spite people like you. I suppose you're the kind of person that prefers the term "Undocumented". Reply 9 months ago. Y'know what I think? A person would have to be living in another universe or have been held underwater for more than five minutes as a child, or be a lifelong Republican in order to think this post makes any sense, whatsoever. Reply 6 years ago. How many people have ever been charged with this for creating a parasitic draw on their own phone line?
Good luck finding even one. Reply 8 years ago on Introduction. Question 2 years ago. Tip 3 years ago. If you have a phone with an answering machine and or with wireless cabability, the phones will not work when the power goes down even the main phone connected to the wall Reply 3 years ago.
The base of my cordless phone system can draw power from a handset during a power loss to keep the phones going. Cool, huh? Unfortunately, now my phone service goes through my modem, so even with a working phone, there's no signal. The absolute maximum voltage rating for a is 35 volts. Even if the line is pulled down some by the current draw, the voltage will still exceed this rating if the phone is disconnected. This is a DIY project.
Some DIY is not logical, just for the hell of it. The designer is experimenting. Help him. Back to Per spec, the designer needs input capacitor and output cap. When drawing more than 20mA, it will be 'off-hook' and the phone line DC Voltage will drop to 7.
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