thanks!? ?I think I saw someone testing this type shield here somewhere.??
Gordon

That will be useful for people who merely need increased oxygen concentration due to SHUNT in their lungs induced by the pneumonia.
But there are much easier ways to do it that are routinely used in the hospital.

The people who are REALLY in trouble require intubation, because putting a plastic tube directly into the Trachea reduces the "dead space" which allows more effective eliimination of carbon dioxide....important in people who have very stiff lungs from pneumonia.? ?The scuba divvers mask by contrast will INCREASE the dead space, which s a problem.

So the need is moslly for buiding the VENTILATOR because endotracheal tubes are cheap.? ?They aare little mmore than a fancy short garden hose.??
Gordon Gibby MD KX4Z

Ashar -- what about gluing a connector to the top of the sensor chip?? ?Then we coud just use a thin tube to go to the airway circuit, which is the NORM in anesthesia and intensitve unit care.? ?All the differential pressure sensors already have the nipple -- this device was made to sense ambient pressure so it didnt have it.

Gordon

I suggest that the pressure sensor be mounted in a 1" PVC T with a threaded leg using a threaded cap. The sensor can be mounted in the cap and wires brought out through a hole easily drilled in the flat cap. If the sensor fails it can be easily replaced.

I'm working on the three passive valves (Anti-Asphyxia, Over-Pressure, PEEP). The approach is to 3D print parts that are attached to 1" PVS pipe Ts. I think that the pressure sensor should also be installed in a T. I'm designing poppet valves with 45 degree seats that have a rubber O-ring embedded. The 1 1/16" OD x 3/32" diameter O-ring is a common hardware store item for faucet valve repair.
The designs are done in OpenSCAD which is freely available and completely parametric. My devices are printed in PETG on a Prusa Research MK3s.
Attached are some pix of the first design. The next design iteration is printing.
I tested the Anti-Asphyxia valve and I'm happy to report I was not asphyxiated.

I mentioned using an Ardunio shield to drive the valve. One class of these boards uses the L293D driver chip, which is rated at 600 ma per a channel on the 4 channel device, with a maximum voltage of 36 volts. This is well de-rated for this application. The board has 16v electrolytic caps on it, so for 12 or 13.6 volts it is fine. The caps would need to be changed if 15 volts is used. I have done this for higher voltage operation in the past with no issues. The particular one that I have is a HiLetgo L293D, but a number of companies make these. The diode should be added to protect the device, otherwise no other mods needed. It can either be added with the valve's leads at the connector, or soldered directly to the board. I used this for a project to open/close car door locks, which electrically is a similar application.

Howard

Draft of layout with connectors
??? Bob? KD8CGH

thanks for running those tests!? good information!!
gordon

From my experiences in building cave radios most connectors leak like this. The idea to pass the wiring through a hole ( with grommet) and seal sounds like the most effective low cost option.

Regards

Ron Taylor G4GXO

开云体育

Well, good to have a group for this.

- Today I've been testing the ic drivers, since I have some parts them at the office and I had some spare time. I'm attaching the schematic I've been using. I had also solenoid valves to test, but their measured internal resistance is 17 Ohms, lower than the 43 Ohms of Gordon's tests.
I let it cycle for a few hours, using square waves generators as inputs, and the ic temperature remained a bit above ambient. Then I pushed the supply to 18V,? and let it cycle for half an hour, and the ic temp stabilized to about 50°C. I assume conditions here are above the real parameters. If the group agrees I may continue with testing with more severe conditions and specific timings, I look forward for your input.
- As per the pcb vs. assembled parts issue, I lean toward designing a proper pcb for the machine. Assembling commercial parts found on Amazon etc. opens the door to several problems of dependability, of the single parts and of the assembled ones (connectors issues, heat managenent and noise problems when you put power or I/O shields over the Arduino, etc.). A decent PCB design does not take weeks and a board can be ordered from the company making it from anywhere, along with standard parts from RS, Farnell Digikey, etc.
I'm shure we can find a pcb manufacturing company that can be interested in being part of this project's devalopment.?
I'd like to hear your opinion on this.

Raf IZ1HNY

Marcelo has changed his interface a little. You can view his video here:
Jack, W8TEE

All:

Please use our group for all communiques from now on, as it will give us a better way to organize information and share ideas.

Jack, W8TEE