[TriEmbed] EL Tape

[Scott Hall]

I'm responding to this online, because more than one person has asked me
the same question lately: they need an easy inverter for driving EL wire
and panels.

First, the specs you sited are not the normal for EL -- usually 80VAC to
150VAC, and 400Hz to about 2kHz.  An old telephone key system ring voltage
(82 - 96VAC, 50Hz) will work, but you want to double the frequency.

The problem with applying ring voltage or mains voltage to EL panels is
that the sine wave signals will appear dimmer, since the maximal voltage is
something less than peak through much of the waveform.  What you want is a
PWM derived waveform where you get the maximal voltage for a pulse (with
pulses alternating positive and negative).

There was an article on this in one of the recent electronics hobbyists
magazines (Nuts & Volts, Circuit Cellar, or Elektor), but I'll have to get
back to you with the specifics when I get home to look it up.

Essentially the author uses a 555 timer to generate the pulses, and drives
a triac or MOSFET to pull the 12VDC through a 120V-to-12V transformer wired
backwards.  The transformer smooths the pulse waveform (distorts it really)
to prevent the corner transients from breaking down the EL material as
fast.  You can use an optoisolator with a darlington pair to drive the
MOSFET, and keep any back transients and surges from weeping back into the
555 control circuit.

Here is an article on one circuit design:
http://electronicsirfan.blogspot.com/2013/11/Triple-555-timer-ic-inverter.html

[image:
http://1.bp.blogspot.com/-Y_iNsG6o--M/UoTaNdrnc7I/AAAAAAAAAcU/TBBw-ZeOsGw/s400/555+timer+IC+based+12V+to+220V+Inverter+circuit+schematic+circuit+diagram.png]

Just use a 12v-to-120v transformer instead.  The frequency here is low
(about 50Hz) -- good for telephone ringers but not so good for EL.

Check this one out -- similar circuit but better frequency:
http://dcroy.blogspot.com/2011/02/555-timer-contest-entry-el-inverter.html

To improve on that some more, check these out:

best one:  *DC to AC Inverter by IC 555 and TIP41 TIP42 | Eleccircuit.com*
http://www.eleccircuit.com/dc-to-ac-inverter-by-ic-555-and-tip41-tip42/

*555 timer IC Inverter 12V to 220V ~ ELECTRONICS LAB*
http://electronicsirfan.blogspot.com/2013/11/Triple-555-timer-ic-inverter.html

Give yourself some control of the flash rate or brightness:
*Electroluminescent (EL) Wire Driver*
http://archive.makezine.com/21/primer/

[image: http://cdn.makezine.com/make/21/elwire-schematic-variant.jpg]

I hope that helps for now.  I'll find that magazine article that discusses
it.

- sgh

On Sun, Mar 15, 2015 at 3:29 PM, Lee Atkinson <latkinso42 at gmail.com> wrote:

> I'm still learning about this myself.
> I bought 6 packs of EL Wire and 1 pack of tape from radio shack.
> operating voltage is 100VAC
> operating frequency is 1600Hz
> power < 0.5w
> Radio Shack used sell a 12 VDC inverter (battery powered)
>
> That's pretty much what I know.
> So I suspect the same invert will work for both tape an wire from radio
> shack.
> This was the one radio shack sold:
>
>
> http://www.radioshack.com/radioshack-12vdc-inverter-for-el-wire-el-tape-el-panel/2760341.html#.VQXbJI4c48E
>
> Inverters themselves just make DC become AC at some frequency (in this
> case we need 1600Hz).
> No tricks .. usually!
> Tricks come with some little micro controller (arduino, rasberry pi,
> beaglebone, or one of the Intel types), but you still need an inverter and
> usually another gadget called a shield, cape or breakout board.
>
> Lee
>
>

-- 
Scott G. Hall
Raleigh, NC, USA
scottghall1 at gmail.com
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