Use your iPad as extra display for your computer

Anyone who wants more space for their computer screen may be interested in how to use your iPad as a second display for your monitor. Of course there is a way to do it with Air Display, but this is a totally different way of doing it, you will also have to have some knowledge of what you are doing as it makes use of just the screen component of the iPad.

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You can pick up LCDs over on eBay and they typically come in at around $50. Typically they have a displayport interface and you can splice the ribbon connector into a displayport cable. The display actually only needs the displayport along with USB to work, however you can also search for components to make the display have higher brightness. So if you fancy having a go yourself check out the steps below.

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First, pickup a premade breakout board along with backlight driver, which you should be able to get around about $35 from here.

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You can see the LCD working on the board below which is working on power off the bench supply.

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When the display is powered by the USB half of the light either doesn’t work or it flickers.

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The controller allowed adjustment of the brightness of the backlight, when lowered the current draw went down to about 600mA.

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Checking out the datasheet for the backlight driver it says that the current limit has been set by resistor based on a formula and so I needed SMD resistors with a limit of 600mA and got them at MITERS. These were then used instead of the stock resistors belonging to the board.

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While this brought the brightness down, it was 600mA and that was still too high for the USB 2 device capped at 500mA. USB 3, which is what the laptop used here was, can give 900mA to devices that are high power USB3 devices.

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In order to be able to pull a fast one and have the computer offer the full USB 3 current, a trip to Microcenter was needed and it cost $10 for a cheap USB 3 hard drive enclosure. The enclosure was stripped and the electronics were compact, luckily. To make it leach power from the board jumpers were added in-between the power pins and LCD driver board.

[Image Source: Build-its]

Here you can see the display running on the mini display port along with the USB port.