Made a little booster circuit similar to the one in the Nerdkits tutorial. This one use an H-bridge to convert the DC to AC unlike Mike's. It also has an input button so that different modes of operation can be entered and has led's to display which mode you're in (3 bits so 8 modes, the pic shows one led on so it's in mode 1). I have it putting out about 120v peak to peak at 80hz with 12v DC in.

Eagle layout and schematic are posted at: http://www.batchpcb.com/index.php/Products/76411

Eric

So Eric you have made a "inverter" what might the ampacity (wattage) be?

Ralph

Ralph,

When driving the two ten foot long EL wires shown in the second picture above, I estimate it is running at about 2-3 watts. All of the component are rated for much higher, but I wanted it to run cool, which it does (all cool to the touch, after running continuously).

Eric

Speaking of SMD soldering in another thread, did you hand solder that or reflow in the frying pan?

Either way, you are getting quite good at it

Rick

How much light do you get from the EL?

I am doing a brick path and need to do some lighting I am thinking about maybe wrapping the lamp post.

We want more subdued lighting nothing particularly bright.

Ralph

Ralph,

If you were looking to directly illuminate the borders of a path, these would probably work and would fit the bill as subdued, but these particular wires don't throw enough light to give you area illumination if that's what you need.

Rick,

This was done using reflow. It really hasn't taken too long to get it to work well, TFQP is starting to feel easy but QFN packages are still a little intimidating and require a bit of extra attention. I got a hot air rework machine too that helps too.

Eric

How long can the EL wires be and would they stand being exposed to the weather or would they need to be encased in a tube.

I would not need them for illumination just for effect.

I am picturing wrapping three light post and possible just running along side the path.

It would be cool if I could do a moving bright spot.

Ralph

Ralph,

I have two ten foot wires, but they could be of any length you could buy or splice together. Power draw is proportional to the total length.

The wires themselves should be weather proof and wouldn't need further protection.

Eric

Thanks Eric, I looked on WiKipedia and they show the construction of the EL.

They say 1000Hz but you are using 80Hz.

Ralph

Ralph,

The datasheet for the EL wire I've got says 50-2000 hz. I could probably continue to tweek the frequency I'm feeding into the EL wire (its all software configurable on my setup). But given the output I've got coming out of the buck boost portion of the circuit with present settings, if I raise the output frequency on the H-bridge powering the capacitive load of the EL wire too much I start to lower the peak to peak voltage. I have no doubt that further adjustments could be made that would be more optimal, but I was already getting the results I wanted so I didn't keep looking.

Eric

Ok new subject but relevant to the thread I hope.

I also wanted to ask Rick about this.

The ATmega chip which I assume is the square object in the lower left is soldered in place (you did a very nice job as Rick noted).

Now you say:

"I could probably continue to tweek the frequency I'm feeding into the EL wire (its all software configurable on my setup)."

Do you have a serial/usb port on your card to change the program (software/configurable)?

That is why I use sockets so I can pop the mcu out to place in a programmer but once it is soldered in place you are either suck with your hardcoded code or you have a serial/usb port.

Ralph

Ralph,

I have a ICSP (AVRISP mkII) so I program the MCU via the six pins near the center of the pcb. All of the pcb's I've designed with the 168/328 mcu have included a pinout for ICSP so I can always update the software when needed.

Eric

So you have a SPI header onboard for programing.

Not sure of the advantage over using the two serial pins but at least you can program an inplace mcu which is what is important.

Ralph

Hey Eric, where might I buy 150' lengths of EL wire?

Most sources just list 10' to 13'.

Could your circuit power150' of EL?

Ralph

Ralph,

This site sells longer EL wire: http://www.elbestbuy.com/liwicule.html

I've driven only 10' and 20' wires with my circuit so I can't say definitively that it would work for 150'; it seems to handle the 20' easily.

Eric

Thanks Eric, now that I am seeing some prices my 130' - 150' path project probable is not feasible (aka affordable).

To bad it would have a nice effect.

Also one site says to not consider exterior installations as permanent, probable the UV degrades the EL.

Ralph