Topics

Ventilator

Gordon Gibby
 

A bit off topic! I got asked to help build a ventilator for a low-cost application to save lives in COVID-19. A few brilliant engineers at the University of Florida are building a ventilator using cheap lawn sprinkler valves & pvc pipe to direct compressed oxygen gas. They needed a control system to manage the inspiratory and expiratory valves.

With What I have learned from Farhan and everyone here, I suggested the Arduino was the way to go;

Last night and today I started building the little transistor drivers to handle the sprinkler valves. The only NPN power transistors I could find in the entire house were 2N3055s. Then I wrote a simple program to read a potentiometer to adjust ventilatory rate, and for starters, set the I to E ratio at the normal 1 to 2. Using the potentiometer, the respiratory rate can be varied from 10 to 30. They have simple spring mechanisms to create positive end expiratory pressure. The prototype is working on my kitchen table, and I’m waiting for the mechanical engineer to drive over with the plumbing apparatus and the valves.

Your building this open source, some of you really bright folks might want to jump in and help them with the software, if so email me and I will help get you into the group. my part was just the simple transistor switches.

Ashar— We may have a new product for you to build quickly. And I’m sure you could make it a lot better


Gordon Gibby KX4Z

_Dave_ AD0B
 

Gordon Atta boy. 
--
73
Dave
ADOB
Raduino bracket and Ham_Made_Keys

Jack, W8TEE
 

Gordon:

Let me know if I can help.

Jack, W8TEE

On Sunday, March 22, 2020, 4:33:49 PM EDT, Gordon Gibby <docvacuumtubes@...> wrote:


A bit off topic!  I got asked to help build a ventilator for a low-cost application to save lives in COVID-19. A few brilliant engineers at the University of Florida are building a ventilator using cheap lawn sprinkler valves & pvc pipe  to direct compressed oxygen gas.  They needed a control system to manage the inspiratory and expiratory valves.

With What I have learned from Farhan and everyone here, I suggested the Arduino was the way to go;

Last night and today I started building the little transistor drivers to handle the sprinkler valves. The only NPN power transistors I could find in the entire house were 2N3055s.  Then I wrote a simple program to read a potentiometer to adjust ventilatory rate, and for starters,  set the I to E ratio at the normal 1 to 2.  Using the potentiometer, the respiratory rate can be varied from 10 to 30.  They have simple spring mechanisms to create positive end expiratory pressure.  The prototype is working on my kitchen table, and I’m waiting for the mechanical engineer to drive over with the plumbing apparatus and the valves.

Your building this open source, some of you really bright folks might want to jump in and help them with the software, if so email me and I will help get you into the group.  my part was just the simple transistor switches.

Ashar— We may have a new product for you to build quickly.  And I’m sure you could make it a lot better


Gordon Gibby KX4Z



--
Jack, W8TEE

ajparent1/kb1gmx
 

Gordon,

Over pressure and under pressure is actually a small differential
more than that and it can cause damage.

The basic mechanism has two factors management and reliability of
the system.  The latter has to insure there are no hard transients
or misses.

The older way was the box with the head out, iron lung, though the box
could easily be plywood glued up.  A variable displacement bellows d
id the work with a motor.

Allison
---------------------------------
No direct email, it goes to bit bucket due address harvesting in groups.IO

Gordon Gibby
 

Perfect.  I’m going to forward this



On Mar 22, 2020, at 17:03, Jack, W8TEE via Groups.Io <jjpurdum@...> wrote:


Gordon:

Let me know if I can help.

Jack, W8TEE

On Sunday, March 22, 2020, 4:33:49 PM EDT, Gordon Gibby <docvacuumtubes@...> wrote:


A bit off topic!  I got asked to help build a ventilator for a low-cost application to save lives in COVID-19. A few brilliant engineers at the University of Florida are building a ventilator using cheap lawn sprinkler valves & pvc pipe  to direct compressed oxygen gas.  They needed a control system to manage the inspiratory and expiratory valves.

With What I have learned from Farhan and everyone here, I suggested the Arduino was the way to go;

Last night and today I started building the little transistor drivers to handle the sprinkler valves. The only NPN power transistors I could find in the entire house were 2N3055s.  Then I wrote a simple program to read a potentiometer to adjust ventilatory rate, and for starters,  set the I to E ratio at the normal 1 to 2.  Using the potentiometer, the respiratory rate can be varied from 10 to 30.  They have simple spring mechanisms to create positive end expiratory pressure.  The prototype is working on my kitchen table, and I’m waiting for the mechanical engineer to drive over with the plumbing apparatus and the valves.

Your building this open source, some of you really bright folks might want to jump in and help them with the software, if so email me and I will help get you into the group.  my part was just the simple transistor switches.

Ashar— We may have a new product for you to build quickly.  And I’m sure you could make it a lot better


Gordon Gibby KX4Z



--
Jack, W8TEE
<Video.mov>

Ashhar Farhan
 

Gordon and guys
I have volunteered with the open source ventilators group. India will need this more than anyone else. We are potentially looking at a death toll of 10 million without the ventilators, (no kidding). let's take this offline (Jack, will you form a cc list?) I dont want to spook others with the grimness all around. 
73. f

On Mon, Mar 23, 2020 at 2:33 AM Jack, W8TEE via Groups.Io <jjpurdum=yahoo.com@groups.io> wrote:
Gordon:

Let me know if I can help.

Jack, W8TEE

On Sunday, March 22, 2020, 4:33:49 PM EDT, Gordon Gibby <docvacuumtubes@...> wrote:


A bit off topic!  I got asked to help build a ventilator for a low-cost application to save lives in COVID-19. A few brilliant engineers at the University of Florida are building a ventilator using cheap lawn sprinkler valves & pvc pipe  to direct compressed oxygen gas.  They needed a control system to manage the inspiratory and expiratory valves.

With What I have learned from Farhan and everyone here, I suggested the Arduino was the way to go;

Last night and today I started building the little transistor drivers to handle the sprinkler valves. The only NPN power transistors I could find in the entire house were 2N3055s.  Then I wrote a simple program to read a potentiometer to adjust ventilatory rate, and for starters,  set the I to E ratio at the normal 1 to 2.  Using the potentiometer, the respiratory rate can be varied from 10 to 30.  They have simple spring mechanisms to create positive end expiratory pressure.  The prototype is working on my kitchen table, and I’m waiting for the mechanical engineer to drive over with the plumbing apparatus and the valves.

Your building this open source, some of you really bright folks might want to jump in and help them with the software, if so email me and I will help get you into the group.  my part was just the simple transistor switches.

Ashar— We may have a new product for you to build quickly.  And I’m sure you could make it a lot better


Gordon Gibby KX4Z



--
Jack, W8TEE

Gordon Gibby
 

Jack, can you send me a personal email address to docvacuumtubes@ gmail.com ?  The folks at QRZ do not want me using their services. 




On Mar 22, 2020, at 17:03, Jack, W8TEE via Groups.Io <jjpurdum@...> wrote:


Gordon:

Let me know if I can help.

Jack, W8TEE

On Sunday, March 22, 2020, 4:33:49 PM EDT, Gordon Gibby <docvacuumtubes@...> wrote:


A bit off topic!  I got asked to help build a ventilator for a low-cost application to save lives in COVID-19. A few brilliant engineers at the University of Florida are building a ventilator using cheap lawn sprinkler valves & pvc pipe  to direct compressed oxygen gas.  They needed a control system to manage the inspiratory and expiratory valves.

With What I have learned from Farhan and everyone here, I suggested the Arduino was the way to go;

Last night and today I started building the little transistor drivers to handle the sprinkler valves. The only NPN power transistors I could find in the entire house were 2N3055s.  Then I wrote a simple program to read a potentiometer to adjust ventilatory rate, and for starters,  set the I to E ratio at the normal 1 to 2.  Using the potentiometer, the respiratory rate can be varied from 10 to 30.  They have simple spring mechanisms to create positive end expiratory pressure.  The prototype is working on my kitchen table, and I’m waiting for the mechanical engineer to drive over with the plumbing apparatus and the valves.

Your building this open source, some of you really bright folks might want to jump in and help them with the software, if so email me and I will help get you into the group.  my part was just the simple transistor switches.

Ashar— We may have a new product for you to build quickly.  And I’m sure you could make it a lot better


Gordon Gibby KX4Z



--
Jack, W8TEE
<Video.mov>

Jack, W8TEE
 

I can do that and we'll work from private email. People who want to be involved let me know using this email address:

    jack52443@...

and I will put you on a cc list.

If you don't hear from me immediately, I'll be away from my computer for several hours, but will try to get back to eveyone before midnight EDT. (Too old to think in terms of zulu.)

Jack, W8TEE

On Sunday, March 22, 2020, 5:06:01 PM EDT, Ashhar Farhan <farhanbox@...> wrote:


Gordon and guys
I have volunteered with the open source ventilators group. India will need this more than anyone else. We are potentially looking at a death toll of 10 million without the ventilators, (no kidding). let's take this offline (Jack, will you form a cc list?) I dont want to spook others with the grimness all around. 
73. f

On Mon, Mar 23, 2020 at 2:33 AM Jack, W8TEE via Groups.Io <jjpurdum=yahoo.com@groups.io> wrote:
Gordon:

Let me know if I can help.

Jack, W8TEE

On Sunday, March 22, 2020, 4:33:49 PM EDT, Gordon Gibby <docvacuumtubes@...> wrote:


A bit off topic!  I got asked to help build a ventilator for a low-cost application to save lives in COVID-19. A few brilliant engineers at the University of Florida are building a ventilator using cheap lawn sprinkler valves & pvc pipe  to direct compressed oxygen gas.  They needed a control system to manage the inspiratory and expiratory valves.

With What I have learned from Farhan and everyone here, I suggested the Arduino was the way to go;

Last night and today I started building the little transistor drivers to handle the sprinkler valves. The only NPN power transistors I could find in the entire house were 2N3055s.  Then I wrote a simple program to read a potentiometer to adjust ventilatory rate, and for starters,  set the I to E ratio at the normal 1 to 2.  Using the potentiometer, the respiratory rate can be varied from 10 to 30.  They have simple spring mechanisms to create positive end expiratory pressure.  The prototype is working on my kitchen table, and I’m waiting for the mechanical engineer to drive over with the plumbing apparatus and the valves.

Your building this open source, some of you really bright folks might want to jump in and help them with the software, if so email me and I will help get you into the group.  my part was just the simple transistor switches.

Ashar— We may have a new product for you to build quickly.  And I’m sure you could make it a lot better


Gordon Gibby KX4Z



--
Jack, W8TEE


--
Jack, W8TEE

Bob Benedict, KD8CGH
 

Gordon
  I have arduinos, PIs, breadboards, parts I can use for prototype testing. I can hack code (not elegant), but I'm not an electronics design expert.
   I can also help with design, printing and testing of 3D FDIM parts that might include connectors, adapters, ...
 
     Bob Benedict   KD8CGH, rkayakr at gmail
     retired engineer
     32 years service in new product & process development

Gordon Gibby
 

Thanks to many of you who have stepped up and are deluging with offers of help. Sem has a place where you sign up, and I don’t understand all of that, but he is used to managing projects. all I did was keep people asleep & alive

We took the very prototype system and hooked it to a mechanical test lung and ran it from an air compressor and here is a video of it working. After a few seconds I finally realized I needed to turn to the right so you could see the valve & the ventilator. This particular model uses a fancy balloon inside to shut off the expiratory port during inspiration. However the electronics I built can control a second valve on expiration as well


This simple system is actually very useful— And it’s the kind of technology that ham radio guys understand.




Thanks for all of the interest.
Having a manufacture like Ashar and software engineers and guys with lots of experience will help out a lot. I suspect my little part is finished

Gordon

Jack, W8TEE
 

Use

jack52443@...

Jack, W8TEE

On Sunday, March 22, 2020, 5:08:42 PM EDT, Gordon Gibby <docvacuumtubes@...> wrote:


Jack, can you send me a personal email address to docvacuumtubes@ gmail.com ?  The folks at QRZ do not want me using their services. 




On Mar 22, 2020, at 17:03, Jack, W8TEE via Groups.Io <jjpurdum@...> wrote:


Gordon:

Let me know if I can help.

Jack, W8TEE

On Sunday, March 22, 2020, 4:33:49 PM EDT, Gordon Gibby <docvacuumtubes@...> wrote:


A bit off topic!  I got asked to help build a ventilator for a low-cost application to save lives in COVID-19. A few brilliant engineers at the University of Florida are building a ventilator using cheap lawn sprinkler valves & pvc pipe  to direct compressed oxygen gas.  They needed a control system to manage the inspiratory and expiratory valves.

With What I have learned from Farhan and everyone here, I suggested the Arduino was the way to go;

Last night and today I started building the little transistor drivers to handle the sprinkler valves. The only NPN power transistors I could find in the entire house were 2N3055s.  Then I wrote a simple program to read a potentiometer to adjust ventilatory rate, and for starters,  set the I to E ratio at the normal 1 to 2.  Using the potentiometer, the respiratory rate can be varied from 10 to 30.  They have simple spring mechanisms to create positive end expiratory pressure.  The prototype is working on my kitchen table, and I’m waiting for the mechanical engineer to drive over with the plumbing apparatus and the valves.

Your building this open source, some of you really bright folks might want to jump in and help them with the software, if so email me and I will help get you into the group.  my part was just the simple transistor switches.

Ashar— We may have a new product for you to build quickly.  And I’m sure you could make it a lot better


Gordon Gibby KX4Z



--
Jack, W8TEE
<Video.mov>

--
Jack, W8TEE

Howard Fidel
 

I am a medical device expert. If I can help in anyway, let me know. You can find my bio here:

http://w2hff.xyz/about/default.html

My personal email is howard@...

Howard


On 3/22/2020 4:33 PM, Gordon Gibby wrote:
A bit off topic!  I got asked to help build a ventilator for a low-cost application to save lives in COVID-19. A few brilliant engineers at the University of Florida are building a ventilator using cheap lawn sprinkler valves & pvc pipe  to direct compressed oxygen gas.   They needed a control system to manage the inspiratory and expiratory valves.

With What I have learned from Farhan and everyone here, I suggested the Arduino was the way to go; 

Last night and today I started building the little transistor drivers to handle the sprinkler valves. The only NPN power transistors I could find in the entire house were 2N3055s.  Then I wrote a simple program to read a potentiometer to adjust ventilatory rate, and for starters,  set the I to E ratio at the normal 1 to 2.  Using the potentiometer, the respiratory rate can be varied from 10 to 30.   They have simple spring mechanisms to create positive end expiratory pressure.  The prototype is working on my kitchen table, and I’m waiting for the mechanical engineer to drive over with the plumbing apparatus and the valves. 

Your building this open source, some of you really bright folks might want to jump in and help them with the software, if so email me and I will help get you into the group.  my part was just the simple transistor switches. 
 
Ashar— We may have a new product for you to build quickly.  And I’m sure you could make it a lot better


Gordon Gibby KX4Z



Gordon Gibby
 

Hi -- I forwarded that to Sem.   Thanks!!!
Gordon


On Sun, Mar 22, 2020 at 8:28 PM Howard Fidel <howard@...> wrote:

I am a medical device expert. If I can help in anyway, let me know. You can find my bio here:

http://w2hff.xyz/about/default.html

My personal email is howard@...

Howard


On 3/22/2020 4:33 PM, Gordon Gibby wrote:
A bit off topic!  I got asked to help build a ventilator for a low-cost application to save lives in COVID-19. A few brilliant engineers at the University of Florida are building a ventilator using cheap lawn sprinkler valves & pvc pipe  to direct compressed oxygen gas.   They needed a control system to manage the inspiratory and expiratory valves.

With What I have learned from Farhan and everyone here, I suggested the Arduino was the way to go; 

Last night and today I started building the little transistor drivers to handle the sprinkler valves. The only NPN power transistors I could find in the entire house were 2N3055s.  Then I wrote a simple program to read a potentiometer to adjust ventilatory rate, and for starters,  set the I to E ratio at the normal 1 to 2.  Using the potentiometer, the respiratory rate can be varied from 10 to 30.   They have simple spring mechanisms to create positive end expiratory pressure.  The prototype is working on my kitchen table, and I’m waiting for the mechanical engineer to drive over with the plumbing apparatus and the valves. 

Your building this open source, some of you really bright folks might want to jump in and help them with the software, if so email me and I will help get you into the group.  my part was just the simple transistor switches. 
 
Ashar— We may have a new product for you to build quickly.  And I’m sure you could make it a lot better


Gordon Gibby KX4Z



Jack, W8TEE
 

You're on the list.

Jack, W8TEE

On Sunday, March 22, 2020, 8:28:11 PM EDT, Howard Fidel <howard@...> wrote:


I am a medical device expert. If I can help in anyway, let me know. You can find my bio here:

http://w2hff.xyz/about/default.html

My personal email is howard@...

Howard


On 3/22/2020 4:33 PM, Gordon Gibby wrote:
A bit off topic!  I got asked to help build a ventilator for a low-cost application to save lives in COVID-19. A few brilliant engineers at the University of Florida are building a ventilator using cheap lawn sprinkler valves & pvc pipe  to direct compressed oxygen gas.   They needed a control system to manage the inspiratory and expiratory valves.

With What I have learned from Farhan and everyone here, I suggested the Arduino was the way to go; 

Last night and today I started building the little transistor drivers to handle the sprinkler valves. The only NPN power transistors I could find in the entire house were 2N3055s.  Then I wrote a simple program to read a potentiometer to adjust ventilatory rate, and for starters,  set the I to E ratio at the normal 1 to 2.  Using the potentiometer, the respiratory rate can be varied from 10 to 30.   They have simple spring mechanisms to create positive end expiratory pressure.  The prototype is working on my kitchen table, and I’m waiting for the mechanical engineer to drive over with the plumbing apparatus and the valves. 

Your building this open source, some of you really bright folks might want to jump in and help them with the software, if so email me and I will help get you into the group.  my part was just the simple transistor switches. 
 
Ashar— We may have a new product for you to build quickly.  And I’m sure you could make it a lot better


Gordon Gibby KX4Z




--
Jack, W8TEE

Ashhar Farhan
 

I had mailed some snippets of the code to sem. I am back in action now. Is there a source control or a repository of sorts for this? I would like to get the software sorted out asap.
- f

On Mon 23 Mar, 2020, 7:09 AM Jack, W8TEE via Groups.Io, <jjpurdum=yahoo.com@groups.io> wrote:
You're on the list.

Jack, W8TEE

On Sunday, March 22, 2020, 8:28:11 PM EDT, Howard Fidel <howard@...> wrote:


I am a medical device expert. If I can help in anyway, let me know. You can find my bio here:

http://w2hff.xyz/about/default.html

My personal email is howard@...

Howard


On 3/22/2020 4:33 PM, Gordon Gibby wrote:
A bit off topic!  I got asked to help build a ventilator for a low-cost application to save lives in COVID-19. A few brilliant engineers at the University of Florida are building a ventilator using cheap lawn sprinkler valves & pvc pipe  to direct compressed oxygen gas.   They needed a control system to manage the inspiratory and expiratory valves.

With What I have learned from Farhan and everyone here, I suggested the Arduino was the way to go; 

Last night and today I started building the little transistor drivers to handle the sprinkler valves. The only NPN power transistors I could find in the entire house were 2N3055s.  Then I wrote a simple program to read a potentiometer to adjust ventilatory rate, and for starters,  set the I to E ratio at the normal 1 to 2.  Using the potentiometer, the respiratory rate can be varied from 10 to 30.   They have simple spring mechanisms to create positive end expiratory pressure.  The prototype is working on my kitchen table, and I’m waiting for the mechanical engineer to drive over with the plumbing apparatus and the valves. 

Your building this open source, some of you really bright folks might want to jump in and help them with the software, if so email me and I will help get you into the group.  my part was just the simple transistor switches. 
 
Ashar— We may have a new product for you to build quickly.  And I’m sure you could make it a lot better


Gordon Gibby KX4Z




--
Jack, W8TEE

Puneit Singh
 

Hello Everyone

I am happy to see this here. I am based out of Gurgaon India and have a 3D printer as well. I can solder, assemble and flash firmware etc. 

Will be happy to help and contribute in any way I can. 

Regards
de VU2TUM
Telegram: @puneit
WhatsApp: +919773985545

On Mon, 23 Mar 2020 at 09:54, Ashhar Farhan <farhanbox@...> wrote:
I had mailed some snippets of the code to sem. I am back in action now. Is there a source control or a repository of sorts for this? I would like to get the software sorted out asap.
- f

On Mon 23 Mar, 2020, 7:09 AM Jack, W8TEE via Groups.Io, <jjpurdum=yahoo.com@groups.io> wrote:
You're on the list.

Jack, W8TEE

On Sunday, March 22, 2020, 8:28:11 PM EDT, Howard Fidel <howard@...> wrote:


I am a medical device expert. If I can help in anyway, let me know. You can find my bio here:

http://w2hff.xyz/about/default.html

My personal email is howard@...

Howard


On 3/22/2020 4:33 PM, Gordon Gibby wrote:
A bit off topic!  I got asked to help build a ventilator for a low-cost application to save lives in COVID-19. A few brilliant engineers at the University of Florida are building a ventilator using cheap lawn sprinkler valves & pvc pipe  to direct compressed oxygen gas.   They needed a control system to manage the inspiratory and expiratory valves.

With What I have learned from Farhan and everyone here, I suggested the Arduino was the way to go; 

Last night and today I started building the little transistor drivers to handle the sprinkler valves. The only NPN power transistors I could find in the entire house were 2N3055s.  Then I wrote a simple program to read a potentiometer to adjust ventilatory rate, and for starters,  set the I to E ratio at the normal 1 to 2.  Using the potentiometer, the respiratory rate can be varied from 10 to 30.   They have simple spring mechanisms to create positive end expiratory pressure.  The prototype is working on my kitchen table, and I’m waiting for the mechanical engineer to drive over with the plumbing apparatus and the valves. 

Your building this open source, some of you really bright folks might want to jump in and help them with the software, if so email me and I will help get you into the group.  my part was just the simple transistor switches. 
 
Ashar— We may have a new product for you to build quickly.  And I’m sure you could make it a lot better


Gordon Gibby KX4Z




--
Jack, W8TEE

Tom, wb6b
 

Best wishes on this important project. Here is a link with rough engineering specifications and GitHub links. This looks like the same project as being discussed here.

https://anest.ufl.edu/2020/03/17/cssalt-works-on-open-source-ventilator-design/

Andy_501 <andrew.webb.501.ve4per@...>
 

good luck with efforts. Just found some scary news kind of resembles Nero fiddled while Rome burned though.

https://www.latimes.com/california/story/2020-03-20/coronavirus-county-doctors-containment-testing

On 2020-03-22 8:12 p.m., Gordon Gibby wrote:
Hi -- I forwarded that to Sem.   Thanks!!!
Gordon


On Sun, Mar 22, 2020 at 8:28 PM Howard Fidel <howard@...> wrote:

I am a medical device expert. If I can help in anyway, let me know. You can find my bio here:

http://w2hff.xyz/about/default.html

My personal email is howard@...

Howard


On 3/22/2020 4:33 PM, Gordon Gibby wrote:
A bit off topic!  I got asked to help build a ventilator for a low-cost application to save lives in COVID-19. A few brilliant engineers at the University of Florida are building a ventilator using cheap lawn sprinkler valves & pvc pipe  to direct compressed oxygen gas.   They needed a control system to manage the inspiratory and expiratory valves.

With What I have learned from Farhan and everyone here, I suggested the Arduino was the way to go; 

Last night and today I started building the little transistor drivers to handle the sprinkler valves. The only NPN power transistors I could find in the entire house were 2N3055s.  Then I wrote a simple program to read a potentiometer to adjust ventilatory rate, and for starters,  set the I to E ratio at the normal 1 to 2.  Using the potentiometer, the respiratory rate can be varied from 10 to 30.   They have simple spring mechanisms to create positive end expiratory pressure.  The prototype is working on my kitchen table, and I’m waiting for the mechanical engineer to drive over with the plumbing apparatus and the valves. 

Your building this open source, some of you really bright folks might want to jump in and help them with the software, if so email me and I will help get you into the group.  my part was just the simple transistor switches. 
 
Ashar— We may have a new product for you to build quickly.  And I’m sure you could make it a lot better


Gordon Gibby KX4Z



Gordon Gibby
 

Ashar & Jack — you guys please do software.  make it simple!!!   be finished by Wednesday morning.  when I wake up for real at 1000 zulu I will compile the medical  requirements. 

The valves can be driven with 12 to 14 V DC successfully.   They snap in at a minimum of 10 to 11 VDC.  I think we can run the circuit with a buck boost converter from Amazon creating 13.8 VDC from a 12 V battery being continuously charged by a Walmart 2Amp battery maintainer— We have several digipeters operating for years that way


I will also send out the schematic, which involved arduino output to 20 K ohm resistor driving the base of a 2n3904.     2N3055 (all I could find in the house) switching the valves (snubber diode on the valve) with series 1200 +100 ohms from +13.8 to the base of the 2n3055;  The 2N3904 collector connects to the 100 ohm tap and shorts it to ground when energized by the Arduino through the 10 or 20 KOHm resistor.     Worked perfectly here.  I have not tested it across the temperature range.  My goal was to be certain the transistor is fully saturated when “On”.  Ashar — please do the circuit board & case.  

Valves
The valves have 43 ohms of DC resistance.  Although specified for 24 V AC, two out of two worked perfectly by the time 12 V DC had been reached.   I urged the adoption of 13.8 V DC to give some margin.  They get warm during use

I used a three terminal 5 V regulator to feed the Arduino.   Fed by 13.8, it did OK without a heat sink, but it might be nice to add a small one

The mechanical engineer, Dave Lizdas, used a fascinating balloon system inside the expiratory limb to automatically occlude it during inspiration.

I am concerned that will be difficult to replicate and may be subject to fouling  by respiratory secretions.  Therefore I had provided for two sprinkler valves, one in the inspiratory circuit and one in the expiratory circuit.  Inspiratory Limb is fed by compressed gas at up to about 25 psi, and has mechanical adjustable resistance in series—- pvc valve from Home Depot.   Expiratory limb goes to some form of positive and expiratory pressure, can be as simple as flexible tubing exiting underwater at a depth of 5 to 20 cm underwater.   Spring loaded valve is another possibility.   

Open inspiratory valves and close expiratory valve: patient’s lungs are inflated.  

Close inspiratory valve, open expiratory valve, patient exhales.

Sedated patients can be ventilated with a simple open loop system just like that.

Conscious patients will buck that system if not completely worn out.   Typical “ assist mechanical ventilation “ detects a drop in pressure of about 3 cm-5cm of water Caused by the patient initiatingcaused by the patient initiating an inspiration,  and then immediately kicks in to ventilate a patient with a total volume of adjustable from 400 to 900 mL.    We have not yet written the software for that at all 

Off the top of my head, those are the two major modes of operation. 

more information when I wake up for real. 

Gordon





On Mar 23, 2020, at 00:24, Ashhar Farhan <farhanbox@...> wrote:


I had mailed some snippets of the code to sem. I am back in action now. Is there a source control or a repository of sorts for this? I would like to get the software sorted out asap.
- f

On Mon 23 Mar, 2020, 7:09 AM Jack, W8TEE via Groups.Io, <jjpurdum=yahoo.com@groups.io> wrote:
You're on the list.

Jack, W8TEE

On Sunday, March 22, 2020, 8:28:11 PM EDT, Howard Fidel <howard@...> wrote:


I am a medical device expert. If I can help in anyway, let me know. You can find my bio here:

http://w2hff.xyz/about/default.html

My personal email is howard@...

Howard


On 3/22/2020 4:33 PM, Gordon Gibby wrote:
A bit off topic!  I got asked to help build a ventilator for a low-cost application to save lives in COVID-19. A few brilliant engineers at the University of Florida are building a ventilator using cheap lawn sprinkler valves & pvc pipe  to direct compressed oxygen gas.   They needed a control system to manage the inspiratory and expiratory valves.

With What I have learned from Farhan and everyone here, I suggested the Arduino was the way to go; 

Last night and today I started building the little transistor drivers to handle the sprinkler valves. The only NPN power transistors I could find in the entire house were 2N3055s.  Then I wrote a simple program to read a potentiometer to adjust ventilatory rate, and for starters,  set the I to E ratio at the normal 1 to 2.  Using the potentiometer, the respiratory rate can be varied from 10 to 30.   They have simple spring mechanisms to create positive end expiratory pressure.  The prototype is working on my kitchen table, and I’m waiting for the mechanical engineer to drive over with the plumbing apparatus and the valves. 

Your building this open source, some of you really bright folks might want to jump in and help them with the software, if so email me and I will help get you into the group.  my part was just the simple transistor switches. 
 
Ashar— We may have a new product for you to build quickly.  And I’m sure you could make it a lot better


Gordon Gibby KX4Z




--
Jack, W8TEE

Gary Anderson
 

The holding voltage of the sprinkler solenoid valve is probably lower than the activating voltage. 
This measurement may be very useful to the others working on the project.

This may lend itself to a quick PWM solution which will help on the temperature of both the driver bipolar and more importantly the 'valve' itself.  It will also lower overall power consumption.

100% peak for the valve turn-on for some period of time, then down to a holding PWM for the remaining time the valve is on.

Gary