# Inverter ICs for (5v DC -> 5v AC) and (9v DC -> 9v AC)

What are some ICs that can turn 5v DC into 5v AC? How about 9v DC into 9v AC?

I'm wiring up the liquid-crystal lenses from active shutter 3D glasses to be electric-powered sunglasses. Depending on the lens model, they need either 5v or 9v to go fully dark.

They can work when powered by DC (which is what I'm currently doing), but this biases the crystal and dramatically lowers its lifespan. Instead, they should be driven by AC with a frequency between 30 Hz - 100 Hz (see: http://www.pacificdisplay.com/lcd_static_drive.htm).

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9V AC RMS (~13V at peak) or 9V at peak? –  Polynomial Jul 23 '12 at 20:56
RMS. Sorry, I was picturing a square wave. Square wave is OK. –  AlcubierreDrive Jul 23 '12 at 20:57

Liquid crystals take very little power to drive, so you don't need a special power circuit for them. The output of a ordinary digital CMOS logic gate will be fine. Some CMOS families can go up to 15 V, so 9 V is doable. OPAMPS can also do this.

You can even create up to 10 V drive level with two 5 V logic outputs run 180° out of phase. With a setup like that, it would be possible to smoothly adjust the effective drive level by changing the phase between two square waves. 0° would be no drive, 180° full 10 V drive, and other phase shifts result in in-between levels.

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But right now I don't have a controller or oscillator to produce the timing. Just use a 555? –  AlcubierreDrive Jul 23 '12 at 21:04
A 666 timer would be just a oscillator and wouldn't able to do the phase shift by itself. If you want a fixed 5 V you could use it directly with just a capacitor for coupling. For fixed 10 V drive, a inverter and capacitor. It seems like you will need to do other things than just drive the LCD, so a microcontroller is the obvious solution. –  Olin Lathrop Jul 23 '12 at 21:42
It's not much of an LCD -- it's literally just one pixel. Which is why I think a controller is overkill. And I don't need any phase shifting -- just 180 deg is fine -- pure dark. –  AlcubierreDrive Jul 23 '12 at 21:45
@JonRod: But what is going to decide when to turn on the LCD? N photosensor? If this needs to be small and light, a small micro wins over a 666 timer any day. –  Olin Lathrop Jul 23 '12 at 22:05
Just a double-pole switch. In my current DC setup a DPDT switch muxes the two wires from the lens to either be shorted or tied to the battery. –  AlcubierreDrive Jul 23 '12 at 22:05