The hardware
The rectangular-profile Aqua Lung i750TC dive-computer body is constructed from high-grade polymers and has a metal screen surround with a black Physical Vapour Deposition (PVD) finish.
The scroll-through menus and functions are accessed via a three-button navigation interface with a Select button on the right and Mode and Advance buttons on the bottom. The OLED display has full hi-vis colour capabilities with user-settable brightness levels.
The i750TC comes with a buckled elastomer strap and an alternate-user changeable baseplate suitable for bungee wrist-mounting.
The computer is powered from a single user-replaceable 3V CR2 lithium battery. Data transfers and firmware upgrades can be made via a supplied USB download cable or via the computer’s integrated Bluetooth smart technology to either iOS or Android smart devices with an optional Diverlog app.
Optional electronic high-pressure transmitters fitted to regulator first stages can be used to send integrated gas information to the screen in real time.

Features
There are four selectable operating modes: Air, Nitrox, Gauge, and Free Dive. In Nitrox mode, the i750TC can manage three different mixes with up to three separate transmitters (each with individual PO2 set points) on a single dive.
Other features include a three-axis digital compass, an option to select deep stops with a countdown timer, an automatic safety-stop countdown displayed in minutes and seconds, and data-retention to maintain settings and calculations between battery changes.
In addition to audible alarms the OLED display has a green, amber and red traffic-light system to provide colour-coded cautions and warnings.

In use
Using the i750TC on an overseas trip, the first thing to do was to enter my personal parameters. I had saved the user manual onto my laptop, but decided to test the intuitivism of the menu system by going in blind.
I found that I could easily navigate my way around, make adjustments, and set up and select gas mixes. What I struggled with initially was how to select and set the screen brightness, though this turned out to be very easy once I’d taken the time to read the manual.
I had chosen the custom bungee-mount, as I think it’s the most secure way to attach what I regard as risk-critical instruments. The curved profile of the mounting-plate matched the shape of my wrist perfectly, and resulted in an extremely comfortable yet snug and secure fit.
Under water and at depth on the first dive, the bright, crisp digits of the OLED display were very easy to see and read.
At shallower depths where the screen had to compete with bright sunshine, it was less so.
The black PVD finish on the screen-surround helped by not allowing any reflected light to reduce the view, but on occasion I still had to cup my free hand over the screen and shield it from the unwanted sunlight to be able to read the information.
What I hadn’t realised was that I’d initially left the screen brightness on its default setting of 60%. Doh!
On subsequent dives, and with the brightness set to maximum, all the information was easy to see, even on the surface and in almost direct sunlight.
The three-axis compass needed to be calibrated before I could use it. This took me less than two minutes, automated instructions displayed on the screen making the process a doddle.
I’m a big fan of digital compasses, and this one proved very intuitive and straightforward, and seemed very accurate.
The display has three segments in what is becoming a standard layout of dive data at the top and centre and gas data at the bottom.
I didn’t have a transmitter to pair with the i750TC, which resulted in the letters “SPG” accompanied by a dive-cylinder symbol on the left side, where real-time tank pressures are displayed when a transmitter is used.
Post-dive information is displayed for a short while before the screen automatically shuts down. The information is still on display when the screen is powered up again, with all the countdowns for desaturation and no-fly periods carrying on behind the scenes.

Conclusion
As my eyesight continues to decay with age, I’m drawn increasingly to bright, colourful OLED displays on the dive-computers I choose to use.
I especially like the traffic-light system of cautions and warnings on this i750TC, because a change from green to amber or red instantly attracts attention.
Another feature I enjoyed during the tests was the custom backplate and bungee-mount.
I find bungees infinitely more comfortable, and they keep everything in place without becoming slack and floppy as depth alters the volume of exposure suits.
I found lots to love about the i750TC – the digital compass, intuitive menus and (once I’d sussed it out) the amazing adjustable OLED display to mention a few.
However, call me an old-fashioned Scrooge but I couldn’t bring myself to part with nearly £20 on apps for my phone and tablet to log my dives, view the profiles and share them on social media.
Instead I downloaded the free “Lite” version, without all the social-media sharing features.

SPECS
PRICE: i750TC £663. Diverlog app £18.99. Hoseless transmitter £204
POWER: User-changeable 3V CR2 li-ion battery
DISPLAY: High-visibility segmented OLED
MOUNTING OPTIONS: Strap and buckle (standard). Backplate and bungee (supplied)
MODES: Air, Nitrox, Gauge, Freedive
GASES: Three nitrox mixes up to 100%
GAS SWITCHING: Yes
HOSELESS INTEGRATION: Yes
COLOURS: Black
CONTACT: www.aqualung.com/uk, App www.ediverlog.com
DIVER GUIDE 9/10