|
Gordon, I have added the level shifter for whatever it is worth. It is already on the PCB. at this point I am not willing to waster another day arguing about it. those who want to solder it in are free to do so. Others who don't have access to those componets?can add a 10 ohm resistor and be done with it. I am not sure when I can get my hands on these parts so I will not want to bring anything into production that I haven't physically verified. USA maybe different. Second, it would border?on a romantic notion that people are going to hand solder this. Just look at the bitx list, how many have hand soldered a bitx? They will solder the modules upside down and diodes in the reverse direction and they will spend weeks pulling their hair out. There will be dry solders, there will be too much heat and there will be misinterpreted instructions. At bitx, we started that way, a bag of parts and a pcb. I distributed a thousand of them at 2014?hamconvention, I know of two people who managed to get it going. That's when we switched to this version where all the SMD is already soldered professionally. It costs us about four dollars to get the SMD done for the full ubitx v6. And I can get 2000 boards done on a single panasonic machine in a day. The scale is just very different.? If we want 10,000 of these boards to be distributed in the next two weeks, we have to autmate?the production. There is no choice.? Later tonight I will push out a version of the schematic with the level shifters and the tested 20x4 display with the switches (4, as Marcelo required them). We have very little time left. In India the virus has already spread to the community (from International travellers) we expect the full load in a week. I am working round the clock to get his out before it is too late.? So if any of you need to discuss any thing call?me on?+91-98490-26029 (I am good on whatsapp). 73, farhan
Friends, I have lost track of some of the responses I read here.
1.? Ashar -- I ordered the BSS138 so that I can check the circuit BUT I MAY NOT HAVE THEM FOR WEEKS!!!!!!? ??
2? The circuit seems very well known.? ?But can I suggest an alternative to this argument that is going on?
a)? BUYING AN ENTIRE LEVEL SHIFTER IS MUCH EASIER FOR ME THAN DEALING WITH THIS BSS138 -- I have MULTIPLE bidirectional level shifter ALREADY coming to my house that i ordered yesterday.? ?Today I ordered another -- Level shifters are a DIME A DOZEN and there are many many options on the market -- why force the builder to solder a surface mount component if they are a small scale user?? Instead just PROVIDE PADS OR PINS and they can short them out (at their choice) to Bypass, or they can solder in the little Level shifter -- use wires if necessary!!!? That are so ubiquitously available!!!
b)? If you provide the pins or solder pads, then you aallow the building individual or company to solve this however they wish.
The only need for this is to measure a pressure for ALARMS -- It is not part (at the moment) of actually VENTILATING THE PATIENT.? ?This alarm *IS* important, I don't want to downplay tht, but only comes into effect when the ventilator accidentlly comes disconnected? from the patient or the patient coughs up so much that they obstruct the circuit or the tubing get crimped against the bed or something.? ?
Does this make sense?? ? I am FINE with having the pads there for having people populate the BS138 level shifter as well -- if they can get the part!??
I'm also FINE with having Pins or Pads or something that allows them to bypass it or connect to a little daughterboard level shifter (ubiquitoursly available)
There is no way I can test this today, and I won't have a level shifter until tommorrow at the very very earliest and I won't have BS138s for aLONNNNNNGGGG time.
Does that help?
Gordon
|
Ashar -- FANTASTIC!!!!!!? ?More power to you.? ?Please put out current schematic and current printed circuit board design when you can, so i can update my information, and if possible include a PDF of the board/traces.? ?I have just loaded KICAD so **maybe** I can load it.
(GRIN)? I am certain you are correct about the ability of people to solder......you're correct.? ?I hand soldered the BMP yesterday?to allow me to be certain it works.? ?That was hard.? ?I believe another person is making a through-hole version of the printed circuit board.? ?
The University of Florida is not a manufacturer, but we have a ham radio manufacturer (I''m not sure if I'm allowed to mention their name) who is watching this VERY closely and may either?do thousands of your board -- or redesign the entire thing with a different processor overnight.? ?That is up to them -- we just have to GET SOMETHING DONE HERE.? ?I agree?with your sense of urgency and have been pushing the younger engineerings like Crazy at the University of Florida.? ?
Gordon
On Sun, Mar 29, 2020 at 8:07 AM Ashhar Farhan < farhanbox@...> wrote: Gordon, I have added the level shifter for whatever it is worth. It is already on the PCB. at this point I am not willing to waster another day arguing about it. those who want to solder it in are free to do so. Others who don't have access to those componets?can add a 10 ohm resistor and be done with it. I am not sure when I can get my hands on these parts so I will not want to bring anything into production that I haven't physically verified. USA maybe different. Second, it would border?on a romantic notion that people are going to hand solder this. Just look at the bitx list, how many have hand soldered a bitx? They will solder the modules upside down and diodes in the reverse direction and they will spend weeks pulling their hair out. There will be dry solders, there will be too much heat and there will be misinterpreted instructions. At bitx, we started that way, a bag of parts and a pcb. I distributed a thousand of them at 2014?hamconvention, I know of two people who managed to get it going. That's when we switched to this version where all the SMD is already soldered professionally. It costs us about four dollars to get the SMD done for the full ubitx v6. And I can get 2000 boards done on a single panasonic machine in a day. The scale is just very different.? If we want 10,000 of these boards to be distributed in the next two weeks, we have to autmate?the production. There is no choice.? Later tonight I will push out a version of the schematic with the level shifters and the tested 20x4 display with the switches (4, as Marcelo required them). We have very little time left. In India the virus has already spread to the community (from International travellers) we expect the full load in a week. I am working round the clock to get his out before it is too late.? So if any of you need to discuss any thing call?me on?+91-98490-26029 (I am good on whatsapp). 73, farhan
Friends, I have lost track of some of the responses I read here.
1.? Ashar -- I ordered the BSS138 so that I can check the circuit BUT I MAY NOT HAVE THEM FOR WEEKS!!!!!!? ??
2? The circuit seems very well known.? ?But can I suggest an alternative to this argument that is going on?
a)? BUYING AN ENTIRE LEVEL SHIFTER IS MUCH EASIER FOR ME THAN DEALING WITH THIS BSS138 -- I have MULTIPLE bidirectional level shifter ALREADY coming to my house that i ordered yesterday.? ?Today I ordered another -- Level shifters are a DIME A DOZEN and there are many many options on the market -- why force the builder to solder a surface mount component if they are a small scale user?? Instead just PROVIDE PADS OR PINS and they can short them out (at their choice) to Bypass, or they can solder in the little Level shifter -- use wires if necessary!!!? That are so ubiquitously available!!!
b)? If you provide the pins or solder pads, then you aallow the building individual or company to solve this however they wish.
The only need for this is to measure a pressure for ALARMS -- It is not part (at the moment) of actually VENTILATING THE PATIENT.? ?This alarm *IS* important, I don't want to downplay tht, but only comes into effect when the ventilator accidentlly comes disconnected? from the patient or the patient coughs up so much that they obstruct the circuit or the tubing get crimped against the bed or something.? ?
Does this make sense?? ? I am FINE with having the pads there for having people populate the BS138 level shifter as well -- if they can get the part!??
I'm also FINE with having Pins or Pads or something that allows them to bypass it or connect to a little daughterboard level shifter (ubiquitoursly available)
There is no way I can test this today, and I won't have a level shifter until tommorrow at the very very earliest and I won't have BS138s for aLONNNNNNGGGG time.
Does that help?
Gordon
|
Bob¡ the flow sensor main board requirements: ? -????????? A ground/ reference pin. -????????? A pin that goes to an analog pin on the Arduino for A/D resolution. -????????? A ¡°power Pin¡±¡ as some of these devices take power.? It could be EITHER 3.3 or 5 VDC depending upon the selected device. ? I¡¯ll let you figure out how you want to terminate this etc.? You will be getting 2 or 3 wires from the sensor. ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: Like us on Facebook! ? Moderator ¨C North American QRO Group at Groups.IO. ? email:? bill@... ? ?
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of Bob WO6W
Sent: Sunday, March 29, 2020 5:00 AM
To: [email protected]
Subject: Re: [VentilatorDevelopers] First look, PCB? 2. we are not going to have a general purpose 'experimenters area' so, if there is more circuitry coming in, we either put it in now or not. just leaving open pcb out is not going to be of any use.? ? Wasn¡¯t suggesting experimenters area¡ just having some extra space so adding a couple of sot-23 wouldn¡¯t require a new pcb outline and case. Not critical¡ ? Going to use a different data sheet for the LCD¡ part I sent a few minutes ago has at least one error in dimensions¡ bottom right hole has an edge just slightly outside the edge of the board as drawn. ? Will send the sheet when I have it. ? B ? ? ? From: [email protected] [mailto:[email protected]] On Behalf Of Ashhar Farhan
Sent: Sunday, March 29, 2020 2:54 AM
To: [email protected]
Subject: Re: [VentilatorDevelopers] First look, PCB ? 1. I am have redone the schematic with the leve shifters. at this point, 2. we are not going to have a general purpose 'experimenters area' so, if there is more circuitry coming in, we either put it in now or not. just leaving open pcb out is not going to be of any use.? 3. The test points are on the Arduino itself or the end connectors. the aruidno nano comes with clearly marked pins that can be probed. ? On Sun, Mar 29, 2020 at 3:19 PM Bob WO6W <bobhome@...> wrote: I¡¯d suggested a larger pcb¡ room for the circuits we haven¡¯t realized we need at this time Very little cost increase at most fabs I¡¯ve used. Then again, time pressure! ? The MOSFET in the level shifter are not magic parts¡ There are certainly other low Vgs parts that will work. Maybe let me know what parts you have available and I can look for a likely candidate? ? The level translator circuit topology is used on MANY level shift modules such as this: It¡¯s a tried and true circuit¡ We could see what other MOSFET have been used if people have these and can check what parts were used. For now, if you do include the circuit, populate the 0-ohm resistor, leave the MOSFET off and only use one set of pull-up resistors. ? For pull-ups¡ 1.47k and 1.9K are not magic values¡ Anything in that general area would be fine. Just looking for sufficient pull-up current to handle more than usual capacitance on the lines. The 3.3V side is where it matters the most¡ much less so on the very short low capacitance 5V side. If you like, let me know a few values you have available and I can check them against the tables. Again, not critical values! ? I¡¯ll put together a footprint for the much larger 4x20 display. The smaller 4x20 was from a link you had in the schematic. It was such a nice fit to the available space! ? Into the footprint editor! ? Using this generic display for dimensions¡ 97 mm x 60 mm which is typical for the commonly available display. ? Bob ? From: [email protected] [mailto:[email protected]] On Behalf Of Ashhar Farhan
Sent: Sunday, March 29, 2020 1:32 AM
To: [email protected]
Subject: Re: [VentilatorDevelopers] First look, PCB ? the board will have to be redone for the level shifters. there isn't enough space on this on the current layout. Let's move the close-by date to monday to get this done. We won't be able to close this now. I would also want to have the footprints of the level shifter transistor?as I couldnt?locate them anywhere on kicad.? The 1.47k and 1.9k resistor values are not readily available and other values are not going to work, making it unreliable.? I have tried to keep the reuse the same resistor values everywhere to make it easier to source the components?and stuck to just two (or three) resistor values. We will need to procure 1.9K and 1.47K resistors. Your best bet is to procure them from mouser. Gordon can you please try out this circuit on the BMP280 to check if it is working? We need someone to validate this in the next few hours ? On Sun, Mar 29, 2020 at 1:50 PM Tom, wb6b <wb6b@...> wrote: On Sun, Mar 29, 2020 at 01:07 AM, Ashhar Farhan wrote: Given the barbarians at the door,
Bob's design included a 0 ohm resistor to bypass the level shifters. If the level shifters are not obtainable in India I understand the tradeoff greatly goes for getting something out there to start saving lives now. Maybe a alternative mosfet will be found for your needs. But, I understand why you need to go ahead now.
But, the level shifters should be an option where the mosfets are available.
Tom
|
Pretty easy with a piezo buzzer and the Tone library.
Jack, W8TEE
On Saturday, March 28, 2020, 11:14:46 PM EDT, Marcelo Varanda via Groups.Io <mv_email@...> wrote:
Trying once again: consider implementing an oscillator with that OA or replace it by a 555 or by the already suggested buzzers.
thanks
|
I have KICAD installed and astonishingly, I was able to open Ashar's yesterday-project and actually see the board he proposed.? ?Now I may be able to follow other developers as well much more easily.
|
Our volunteer prototype-fabricator here on Campus at the University of florida has limitations and suggestions for you to make it easier for other people to fabricate who are similliarly limited -- dont know how much you can do...here is what he wrote:
Editing the print now, some features too small. ?Since I¡¯m not as adept at KiCAD as Ashhar, please have him 1) increase the size of all pads and 2) use the same drill size for?all?holes, this will make fabrication much easier if it is not being done by a ¡°board shop¡±.
|
I¡¯ll contact the SF area board shops I used for company fabs¡ They can do impressively fast turn on boards ¨C especially for the low complexity we have here. They might do a run for us gratis given the urgency. No promise, but worth a try. ? Will do the same for local small lot assembly houses. ? I personally have hobby level reflow capability here at home as well as decent smd rework tools and skills. I could build and ship a small number of boards in a day. Old eyes, good tools! The Whizoo reflow toaster rocks¡ ? Bob ? ? ?
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of Gordon Gibby
Sent: Sunday, March 29, 2020 9:17 AM
To: [email protected]
Subject: Re: [VentilatorDevelopers] First look, PCB ? Our volunteer prototype-fabricator here on Campus at the University of florida has limitations and suggestions for you to make it easier for other people to fabricate who are similliarly limited -- dont know how much you can do...here is what he wrote:
Editing the print now, some features too small. ?Since I¡¯m not as adept at KiCAD as Ashhar, please have him 1) increase the size of all pads and 2) use the same drill size for?all?holes, this will make fabrication much easier if it is not being done by a ¡°board shop¡±.
|
WOW!!!? an asst. professor of EE at UF is very close to having the FIRST BOARD fabricated!!!? ?I need to get cleaned up, I think I'm going to be soldering a prototype within hours......
Great going guys!!
Gordon
|
All:
I got Marcelo's code working, but have not added the switches yet (only one). His code is very modular with 18 source files. While that sounds complex, it actually makes things easier because: 1) there is only 1 ino file, so it's fast to find the setup() and loop() functions, and 2) with only 1 ino file, the IDE supports incremental compiles. When you do a bazillion compiles a day, the time savings add up. I'm also going to see if I can move the "on screen" prompts and messages to a single file, so that if someone needs to translate to a different language, they're all in one place.
People should know that the code I have (download several days ago, so it may have changed) is set up for Marcelo's simulator. If you put this line at the very top:
? #undef VENTSIM
it toggles the simulator off. Also, if you are using an I2C LCD display, which I am, line 68 in hal.cpp is currently:
? lcd.init();?
I changed this to:
//? lcd.init();????????????????????? // initialize the lcd
? lcd.begin();????????????????????? // initialize the lcd
because my I2C library uses the method begin() rather than init(). Yes, someone thought it would be a good idea to have the LCD libraries use the same name, even though they are different. You may have to experiment.
Now, I'm going to add the rest of the switches and see if I can match the schematic pins to Marcelo's code.
Jack, W8TEE
On Sunday, March 29, 2020, 2:03:19 PM EDT, Gordon Gibby <docvacuumtubes@...> wrote:
WOW!!!? an asst. professor of EE at UF is very close to having the FIRST BOARD fabricated!!!? ?I need to get cleaned up, I think I'm going to be soldering a prototype within hours......
Great going guys!!
Gordon
|
jjpurdum
