DIY CPAP machine

A well designed trompe could suply air at the needed pressure with only a few feet of head.
http://en.wikipedia.org/wiki/Trompe

Considering the progress being made with solar cells, the real issue here is political: CPAP machines are regulated as medical devices. If that were not an issue, a truly free market could make a modern style simple CPAP machine very inexpensive.

How about a project to make CPAP machines that currently end up in a landfill available to the third world instead?

policebox wrote:You should try making a CPAP machine powered by energy generated through pedaling a stationary bicycle.

Travel somewhere that you can hire one of the locals cheaply to turn a crank all night long.

GumbyCT wrote:

naginalf wrote:

archangle wrote:How do you expect to power your camping CPAP without batteries or electrical power?

Gravity and possibly some mechanical advantage.

It's called a dental device.

naginalf wrote:Yup, not gonna happen. Sorry to waste your time.

I guess I was the closest eh.

JackLaBear wrote:Compressed air is a viable means of storing energy, as an alternative to batteries: http://en.wikipedia.org/wiki/Compressed ... gy_storage
You don't need a turbine generator to run an electric blower, or any moving parts at all:
https://www.gyroscope.com/d.asp?product=AIRAMPLIFIER
Regarding feedback control systems, it can be done with fluidics instead of electronics:
http://en.wikipedia.org/wiki/Fluidics
Now, there is still the issue of "charging" the system when you're not sleeping. How about a pedal or windmill powered compressor? Solar cells
You say you want it for camping. Does that mean you want something you can carry in a backpack? You could probably sustain 40W into a lightweight hand pump for 2-3 hours a day.
If you're considering patenting these ideas, you'll need to count me in as this post represents published prior art!

Compressed air just doesn't store enough energy vs. size, weight, cost, and safety to be competitive with batteries in most cases, especially camping. We've been looking really hard for good alternatives to batteries for energy storage since the 1970's energy crisis. We've made some advances in batteries, but we haven't found anything that beats them in most cases.

Fuel cells could do the job, but are expensive and unreliable at present.

If someone made a really small gasoline or alcohol powered generator, that could do the trick.

CPAP just takes more energy than is convenient to carry backpack camping.

Solar cells might work if you're in a fixed location, without too much shade, too many clouds, etc. If the solar cell is in your backpack while you're hiking to another location, it doesn't charge anything. It takes a fairly large solar cell array to get enough power to run a CPAP all night.

If you want to put a lower limit on the power consumption a CPAP blower has to consume, do the following thought experiment. Assume the blower blows some leak rate such as 30 L/m at some pressure such as 10 cmH20. Imagine a frictionless vertical cylinder. Pump CPAP air in at the bottom. Put enough weight on the top such that there is 10 cmH2O pressure in the air in the cylinder. Figure out how far the weight rises in one minute. Multiply the weight by the height and you get the energy produced in one minute. Calculate the power that amounts to. Any working CPAP machine will consume at least that much power at that leak rate and pressure.

You can't possibly build a more efficient blower because if you did, you could build a perpetual motion machine.

It doesn't matter what kind of mechanism you use. It could be bellows, a fan, a cylinder, electrostatic ion streams, or force fields. Energy out will not be more than energy in, or you've got a really good idea to patent.

You can assume that ANY idea you have has been thought of by someone else. Moving from an idea to a marketable produce is hugely difficult. Throw in the fact that you are talking about a medical device and multiply the difficulties and expense by 10 (that's ridiculously conservative).

In other words 'forgetaboutit'

That is a solution that requires no power source. You just need about 150 kg of forages per day.

-tim wrote:

akcpapguy wrote:If you disassembled it quickly, you could miss the fact it has 3 pressure tubes from the circuit board to the pressure chambers. I've got no idea if they record pressure, temperature, humidity or level of green slime in the air flow. Since two sensors are on opposite ends of a Venturi device I'm guessing they are used to deduct air flow.

I believe it's a venturi or restriction in the flow stream, with two tubes going to a differential pressure sensor. That gives you an airflow sensor.

One separate tube going to a pressure sensor is used to control pressure.

JackLaBear wrote:A well designed trompe could suply air at the needed pressure with only a few feet of head.
http://en.wikipedia.org/wiki/Trompe

Considering the progress being made with solar cells, the real issue here is political: CPAP machines are regulated as medical devices. If that were not an issue, a truly free market could make a modern style simple CPAP machine very inexpensive.

How about a project to make CPAP machines that currently end up in a landfill available to the third world instead?

Awesome, and that brings up another possibility even if you didn't use a trompe (not sure it could be made small enough, but not ruling it out), as long as you are camping near flowing water. Hmm.

Wait someone else mentioned that in an earlier post as well didn't they, kudos. Love the ideas floating around here.

Speaking of, the didgeridoo idea would be great to do around the campfire before bed. Except I personally cannot for the life of me get my head around circular breathing and just end up hyperventilating, . Losing weight would not help me either (camping is part of that) because after getting on a CPAP, I discovered that I've always had sleep apnea. I've always slept badly my whole life and after getting on a CPAP I went from being able to sleep for as much as 14 hours with no refreshment to never needing more than 6-8 and feeling great.

akcpapguy wrote:I wasn’t asking about the PAP machine listed in your profile to be an ass, I was asking to verify that I was looking at the same machine you were. Since you have verified that it is infact the machine you were referencing, I will tell you that it does indeed have a flow sensor. If you would like I can send you photos of the inside of the machine pointing out where the sensor is located. Once again not trying to be an ass, just trying to clarify.

One thing that most people don’t think about when they are trying to make a DIY PAP machine is that the pressure and flow are never static in a PAP machine. The blower speed in constantly fluctuating as you breath in and out. Without a device to monitor pressure and regulate the blower speed (therefore increasing or decreasing flow), you can never assure proper therapy pressure.

Sorry about that Alaska. You'd think I'd be used to this sort of thing on forums by now, but I was more responding to the general disagreeableness posted than anything else, I didn't mean to imply you were an ass.

Anyway, I'm sitting at home with nothing to do today, so I'm gonna open up my machine again, both to see if I can find the sensor (not that I don't believe you, just like to see how my machines work) and to get a temp probe on that heating plate. BRB.

Hikers could wear heel pumps like in the stillsuits in Dune, to generate power to use at night.

policebox wrote:You should try making a CPAP machine powered by energy generated through pedaling a stationary bicycle.

Hey, if you have RLS, you could pedal in your sleep! That might work!

chunkyfrog wrote:Hikers could wear heel pumps like in the stillsuits in Dune, to generate power to use at night.

I love you now <3 And being a huge dune fan I'm kicking myself for not having thought of that.

naginalf wrote:Anyway, I'm sitting at home with nothing to do today, so I'm gonna open up my machine again, both to see if I can find the sensor (not that I don't believe you, just like to see how my machines work) and to get a temp probe on that heating plate. BRB.

Ok, my memory failed me, I could have sworn I had looked for and not found any sensors, but here they are, plain as day as soon as you open it up . There's even a pressure sensor coming from all the way over on the exhaust of the humidifier. Duh, sorry for the misinformation.


On a DIY side note, anyone with this model will eventually have the heater connector melt on them, even if it was not on recall (like mine) and even if it has been repaired previously. I could not find a use for the connector other than ease of manufacture so I simply soldered the wires directly to the board's pins and covered them with heat shrink. I HIGHLY recommend this fix for anyone no longer renting their equipment and out of warranty. The night it melted on me, I woke up coughing from plastic fumes and found my machine smoking. I work in electronic repair, most of which involves replacing these crappy "Panduit" connectors that are tin plated and "lead free", without which, the tin is prone to corrosion, this causes arching, and the plastic then starts to melt. Here's the board and heater plate:

And you simply flip the board over take out these two connections and solder appropriately if you are so inclined:


Well, I don't have a proper tempurature measuring instrument for this application, and that's a different thread topic anyway, as this post is already bordering on, sorry.

Just go down to Goddfreys and pick up a 50 dollar vacuum cleaner. Rig it to blow instead of suck and gaff tape the nozzle into your mouth every night and silicon your nostrils shut. Open the little pressure port on the handle of the nozzle for C02 expulsion. DIY CPAP done. If you go camping just take a 2 stroke petrol generator with you and that will power your DIY machine. See, we are problem solvers here on CPAPtalk.com!

Sarcasm aside, I think you are being a bit naive in what is involved to build a proper therapeutic CPAP machine. Unless you are a Mechanical engineer with practical experience with ALOT of time and money I wouldn't even try.

Go to google maps on satellite view and look up "1 Elizabeth Macarthur dr Della vista NSW". That is the RESMED facility where RESMED'S machines are made. Not all the parts are made there but a lot of them. I drive past this impressive facility when I am in Sydney down Old Windsor road often and marvel at it's size. That is what is required to build a CPAP machine.

sarcasm back ON/

Matty332 wrote:Go to google maps on satellite view and look up "1 Elizabeth Macarthur dr Della vista NSW". That is the RESMED facility where RESMED'S machines are made. Not all the parts are made there but a lot of them. I drive past this impressive facility when I am in Sydney down Old Windsor road often and marvel at it's size. That is what is required to build a CPAP machine.

To be FAIR:
NOT all of that is for building the machine. Most of it is where re$med piles their extra money

In fact if you zoom in you can see bb smiling

I could be rwong but I think the OP is after the extra money part of cpap