Dive Computers

Open Source Trimix Dive Computer 2n (OSTC 2n)

The OSTC is a robust, easy to use dive computer. It's designed to accomodate any changes in your diving, whatever you decide to do.


The bright, easy to read screen remains, increasing in size to a 2.4" OLED display that is readable in all light conditions without having to press any buttons.


The OSTC is rapidly gaining popularity in Europe. The low cost, combined with modern screen technology and free upgradable software makes it a viable option for many divers.


  Main Features  


The OSTC is an Open Source dive computer. This means that the hardware schematics and software is available for everyone to view, and if you are so inclined, modify. The software is constantly being reviewed, updated and tested to add extra functionality to the unit. This is available to all users at no extra cost.


All OSTC's come loaded with the latest approved release of the software. It uses Gradient Factors to calculate decompression. These are user definable to adapt the decompression profile to suit you and your diving. Other standard hardware features include:

  • Battery life > 30h at maximum brightness in Divemode
  • Charges via any USB Port within 4 hours
  • Two additional status and warning LEDs
  • 4mm highly scratch-resistant borosilicate glass display
  • Electronics completely encapsulated, no airspace left to crush or flood
  • Two Piezo-electric buttons, usable even with extra thick gloves
  • High-tech flex-velcro wristband and built in bungee mount
  • Max depth: 140m (gauge mode, deco mode 100m limit)
  • 70 x 65 x 29 mm (width x height x depth)
  • Weight 160g

There are many customisable functions including the rate to sample depth, warning settings, Gradient factor settings and so on. For a full list please refer to the Online manual as these are upgraded as new software features become available.


The OSTC can currently be used in 6 different modes.

  • ZH-L16 OC: Buhlmann ZH-L16 decompression for Open Circuit
  • ZH-L16 Constant PO2: Buhlmann ZH-L16 decompression for Closed Circuit
  • ZH-L16 GF OC: Gradient Factors decompression for Open Circuit
  • ZH-L16 GF Constant PO2: Gradient Factors decompression for Closed Circuit
  • Gauge mode: No decompression is calculated
  • Apnea mode: No decompression is calculated and depth is sampled every 1 second.

Dive profiles can be downloaded using the appropriate software. The OSTC 2n connects directly to your computer and does not require a hub.




Some of the software features of the latest firmware are below:

  • 5 Preconfigured Trimix gases + 1 Trimix gas configurable during the dive
  • Fixed SetPoint CCR (Three Setpoints + 5 Bailouts)
  • CNS tracking
  • Ascent rate display
  • Battery warning
  • Battery Voltage
  • Status, Warning and No-Fly indicators
  • User definable last stop depth
  • Gauge/Apnea mode
  • 40 Custom Functions See Manual

JDiveLog is an Open Source Logbook with the capability to download OSTC profiles. It can also be used to upgrade your OSTC software. It is Mac and PC compatible.


Diving Log 4.0 is a PC compatible software program with the capability of downloading OSTC profiles. It can be installed as a Shareware version that allows a maximum of 10 dives to be stored, or it can be upgraded to the full version.


Please note: The OSTC 2n does NOT have the Fischer connector so it cannot be linked to Oxygen cells. The new DR5 is designed for this purpose.

For a detailed specification of the hardware and software of the OSTC, please visit the OSTC site.


Please note, this computer is a platform for divers who have an understanding of decompression theory and who believe in transparency in the decompression algorithms being used. As with all software, the stable version supplied with the OSTC may have bugs. Remember - always have a back-up for decompression calculations.

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