Brief Description: Oxygen System - Switching Controller - Part 2
I didn't want to add yet-another gauge on the panel just for measuring the O2 tank pressure. I had a free analog input (Aux3) on the EIS-4000 engine monitoring unit and spent a couple of days working with various bias resistor values and calibration and offset values until I hit upon a combination that gives very accurate readings both on the EIS-4000 display, as well as on the HX engine monitoring displays via the RS232 link. For reference, on AUX3 of the EIS-4000, a 220 ohm resistor to ground and a "3SF" of 2000 and a "3OFF" of 1375 works perfectly.
The remaining feature I wanted was to utilize the "Annunciator Light" function on the Vertical Power VP-200 system to indicate when the Oxygen system was turned on.
So all of that was indeed a pretty tall order. The various switching aspects coupled with the push-on/push-off functionality would require some logic circuitry, as would the Annunciator Light circuit. Additionally, the pressure transducer would need to be biased and interfaced to the EIS-4000. Finally, the logic chips would need a regulated power supply as would the EDS O2D2.
Cont. Next Log...
Oxygen System Controller - Bottom Of PC Board
Oxygen System Controller - PC Board In Project Box
Oxygen System Controller - Electronic Components Soldered To Board
