USB miniUSB port battery to run EL Tape

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ShawnPfendler
 
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USB miniUSB port battery to run EL Tape

Post by ShawnPfendler »

I want to use power bank style batteries, the kind used to recharge a phone using USB/mini USB cable - I want to power some EL Tape. Please help me figure this out.

I will use a battery with USB and miniUSB ports. So, I need to have a cable with a USB or miniUSB male end and, I need to run that to an alternator. Is that right? Can you tell me where to find or, how to make the cable? What alternator do I use?

Then, I should be able to use the EL tape with a cord preattached to each end of the EL tape (& cut the meter of tape in half). I would run that tape's cord to the alternator and then from the alternator to the USB battery. Does that sound right?

Can someone with experience please tell me if my thinking is correct and the easiest way to accomplish this? I just want to power my EL tape using a power bank style battery with USB ports on it.

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adafruit_support_mike
 
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Re: USB miniUSB port battery to run EL Tape

Post by adafruit_support_mike »

The circuit that converts battery power to something an EL wire can use is called an 'inverter'. It converts low-voltage DC power to high-voltage AC power.

EL wire/tape want between 90v and 110v to operate, and any voltage over about 30v is inherently dangerous. It doesn't take much current to induce a heart attack at those levels. If you don't already know how to work with those voltage levels, converting or building an inverter isn't a good DIY project.

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ShawnPfendler
 
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Re: USB miniUSB port battery to run EL Tape

Post by ShawnPfendler »

So, you are saying that, using a battery pack and an inverter designed to power some EL tape, I could kill myself? That is good to know. Thank you very much.

With that said, I still want to accomplish this task. I have a neighbor who is an electrician - I will get his help with the work. Can you suggest the parts we will need, please? And, I would appreciate any more good advice you have for me. I try to maintain a habit of taking good advice. :)

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adafruit_support_mike
 
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Re: USB miniUSB port battery to run EL Tape

Post by adafruit_support_mike »

ShawnPfendler wrote:So, you are saying that, using a battery pack and an inverter designed to power some EL tape, I could kill myself?
It's possible, yes.

A battery-powered inverter isn't as dangerous as some other high-voltage circuits, but people have died from as little as 15mA of 30v AC. You have to learn what kinds of high voltage can hurt you, what situations pose the most risk, and what techniques will allow you to around high voltage safely. Those aren't the kinds of things you want to work out on your own though.
ShawnPfendler wrote:With that said, I still want to accomplish this task. I have a neighbor who is an electrician - I will get his help with the work.
That's good.. someone who already knows how to work with higher voltages can warn you of risks before you find them the hard way.
ShawnPfendler wrote:Can you suggest the parts we will need, please?
To make EL wire work, you need an AC signal of about 15mA at 95v oscillating at 150Hz to 400Hz.

The easiest way to generate that signal from 5v DC is to create an oscillator that sends power through a transformer. Current moving back and forth through the input coil of a transformer induces current in the output coil. The power coming out of a transformer is slightly lower than the power going in, but the ratio of voltages depends on the ratio of turns in the two coils. If the output coil has twice as many turns as the input coil, the output voltage will be twice the input voltage. To keep the power levels equal, the output current will be about half the input current.

To 95v output from a 5v input, you'd need a transformer whose output coil has 19 times as many turns as the input coil. To get 15mA of output from that transformer, you'd need about 300mA moving through the input side.

That's the simple theoretical version of transformer calculations, but getting transformers to work efficiently takes a lot of math. You have to find the correct wire size, coil inductance, and core material to get the right current levels at the lowest overhead, resistive, and core losses.

The upshot is that an efficient transformer that works at 400Hz is fairly bulky.

You can also generate a signal that drives EL wire from a switch-mode power supply. This page has information about building one: http://www.nerdkits.com/videos/backlight/

The basic idea of switch mode power supplies is pretty simple, but making them work reliably takes work.

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