OxyEye Controller

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This page shows a very nice controller. It seems to be primary designed for the use with KISS style rebreathers. Beside the nice design, I think the price is quite attractive. Carlo Marcheggiani build the unit for approx 600 euro. Here is his report:


OxyEye Oxygen Controller for SCR/CCR

By Carlo Marcheggiani 2003

Tekstvak: Low Battery Sign


This is a brief description of the OxyEye oxygen controller for semi/full closed circuit rebreather. The instrument design is based on a Microchip microcontroller that realize the A/D conversion, mathematical calculation, calibration factors storage and display drive. The instrument is able to measure voltages belonging up to three sensors, translate them in PPO2 readings and calculate the average of them. It reads also the battery’s voltage and checks it in real time to generate a “low battery” alarm about one hour before the system shutdown. The “low battery” alarm message is shown for 3 second and it produces a long beep, after this it will show the PPO2 values again and a square sign on the right side of PPO2’s line,
 like shown on fig.1



Other than LCD, the controller drives a Beeper and a two colour light emitting diodes able to give all the information about the PPO2 level according the following table:

The PPO2min limit can be set between 0,16 and 0,21 ATA; the PPO2max limit between 1,55 and 1,70 ATA; the Setpoint between 1,30 and 1,60 ATA enabling the setup menu, holding pressed both buttons after the welcome screen, like fig.2



Fig.2                                                            Fig.3

In fig.3 is shown the calibration menu that appear after the PPO2 limits setup. On the bottom row are shown the sensors voltages  in millivolt. This allow to verify the stability of the reference mix gas in the loop and the goodness of the sensors it selves.


Anyway the calibration routine will exclude the sensors with a poor voltage, marking them with the X sign on the right side of top row. Moreover, it will exclude also the unconnected sensors, marking them with the - (dash) sign. The calibrated sensor will be indicated by the * (star) sign. Excluded sensors, of course will not be considered in the average calculation, like shown on fig.4.



Fig.4                                                            Fig.5

In fig.5 is shown how can you choose the reference gas for calibration, either air or oxygen. It is not possible the casual activation of setup and calibration menus, but is possible, if wanted, to change of PPO2 limits on flight. A serious danger like low PPO2 value will be indicated by a fixed red light, like shown on fig.6.



Fig.6                                                            Fig.7

On fig.7 is shown the blinking (!) green light, because PPO2 is over PPO2min, but under Setpoint (PPO2=0.20 ATA). Notice in the dark picture the backlighted LCD.

On fig.8 is shown the complete system installed on the head of the EDI2002 Semiclosed Rebreather, where are located the 9 Volts battery and two Teledyne R-22D sensors.



The red molex plug connects the third sensor (not installed here) to the HS Eng dive computer.

The OxyEye cabinet was built from a block of aluminium with a black anodized treatment and the window is 6 mm thick polycarbonate. The sealing is a 1,7 mm O-ring. In fig.8 is also visible the left pushbutton. Pushbuttons have no through and through holes, but they use two small magnets to activate two golden reed contacts located inside the cabinet due to avoid flooding. The maintenance of the stainless springs and magnets is possible unscrewing the pushbuttons retainers. The cabinet is kept at ambient pressure (this assures a sealing without environmental pressure limit) via the connection hose that contain also the electrical wiring to sensors, battery and LED. The hose is connected to the rebreather body using a passing through G1/4 connector. The LED cable is connected using a PG7 standard passing through connector. Optionally the controller can drive a solenoid oxygen valve to realize an automated PPO2 control. On this case a battery with bigger capacity is required (in eg. 6 x AA 1,5 V).

For more info please mail to: carlo.speleo@libero.it or edirebs@libero.it .


Carlo, I want to thank you for your efforts putting this report together. I am sure you will get lots of questions. In my opinion it is a nice piece of labor for a most decent price, and the instrument is an important safety factor for KISS and other rebreather divers.

 Cheers Janwillem Bech

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