Emergency Power from a Phone Line

Every one of our readers will experience a power cut at some time, which can be caused by bad weather or problems with electricity lines.

Having supplies such as flashlights and candles are highly recommended but what happens if you need to make a phone call to check on relatives or even contact emergency services?

Eight in ten homes in the UK use a cordless landline telephone. These phones are convenient as you can talk on the phone while doing other things but these phones are very unlikely to work in a power cut, even if they’re fully charged.

Why? The unit (base station) that plugs into the phone socket also needs mains power to operate and rarely has a back-up battery.

If you have a corded phone in the home, this should work fine during a power cut as long as nothing has happened to bring the phone network down. This is because your telephone line takes its power from the local telephone exchange, which has back-up power available.

This emergency power source however, could also be used to charge your USB devices such as your cell phones. It will take a little work from you but it is an easy enough job.

Be aware that this DIY emergency power source should ONLY be used in legitimate emergencies, as it is highly illegal to use phone line power for anything but powering a landline phone. This is also potentially dangerous, since you run the risk of shocking yourself or frying your electronic device if something goes wrong. Don’t do anything stupid or illegal with this information, and if you do, we are not responsible.

You can read through the steps if you prefer the text version rather than the video over on Instructables here. It has some complex-looking wiring diagrams, but the concept is simple: phone cord spliced to a LM7805 voltage regulator, spliced to a USB cable. You can also add a diode to protect your charger if you think anyone might call the phone line.

   

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