DIY CPAP machine

[SleepyToo2]

Maybe he will lose so much weight with creating all that mechanical energy will "cure" his sleep apnea, or he will be too tired to care. Imagine that it takes some time to create the energy, he will be using the machine for one hour, then awake for 4 hours to get another hour of usage. Definitely not my idea of a fun time! The only way you could do it is if you had a water wheel to drive the machinery to raise the weight. And using some mechanical advantage, which means a pulley system. In that calculation you would need to include energy losses due to friction and/or slippage, so an enormous amount of work needs to be done. I prefer to leave it to the enormous turbines at power stations, recharge my battery and sleep soundly for 7-8 hours at a stretch (depending on when the sun/birds wake me)!

[big_dave]

I could be wrong, and I don't mean to be contradictive, but I took my machine COMPLETELY apart and there were no electronics on any of the airways or any tubes branching of to the electronics, just filter => tube => blower => water tank and out the back. There were however 4 wires to the DC motor which tells me that it has a very good RPM sensor.

It's probably a stepper motor, which requires digital control circuitry. One pulse moves the shaft a fixed distance, and a sequence of pulses are needed to turn it. The precise position of the shaft is known at all times, so an RPM sensor is unnecessary and cannot be used. The speed of a stepper motor is controlled by the speed of the pulses, not the voltage applied to it, so it cannot be controlled with a pot knob. See http://en.wikipedia.org/wiki/File:Stepper_Motor_11.jpg

[GumbyCT]

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]

Lol, wow, you guys are awefully serious about a whimsical idea that I thought I stated I was just throwing out there for ideas (not troll bait). If everyone was as much of a downer as that, we'd still be in the stone ages, let alone sleeping well with a CPAP machine. Although I appreciate the work put into making those calculations, you're talking about power from electronics which are notoriously inefficient, I was thinking more along the lines of sheer volume or motor spin and a possibly complicated check valve that would increase the efficiency even more by not pushing air during exhale, no electronics, no heater. But it was just an idea, you guys act like I was speaking blasphemy. Yes that is my machine, why else would I have posted that in my profile, I noticed you jumping down other's throats about it so I made sure to both register AND post my machine. I'll take a picture of the innards, as well as repair I made to the heater connection when I get a chance in hopes that it helps someone else out. But if you guys have some exclusive club here, I'm sorry for intruding and I'll gladly leave if that's what you want. Not much of a forum if so tho.

And as for the rock, lol, so you assume I'd be carrying rocks with me camping instead of picking one of the many lying around .

[pats]

Lol, wow, you guys are awefully serious about a whimsical idea that I thought I stated I was just throwing out there for ideas (not troll bait). If everyone was as much of a downer as that, we'd still be in the stone ages, let alone sleeping well with a CPAP machine. Although I appreciate the work put into making those calculations, you're talking about power from electronics which are notoriously inefficient, I was thinking more along the lines of sheer volume or motor spin and a possibly complicated check valve that would increase the efficiency even more by not pushing air during exhale, no electronics, no heater. But it was just an idea, you guys act like I was speaking blasphemy. Yes that is my machine, why else would I have posted that in my profile, I noticed you jumping down other's throats about it so I made sure to both register AND post my machine. I'll take a picture of the innards, as well as repair I made to the heater connection when I get a chance in hopes that it helps someone else out. But if you guys have some exclusive club here, I'm sorry for intruding and I'll gladly leave if that's what you want. Not much of a forum if so tho.

And as for the rock, lol, so you assume I'd be carrying rocks with me camping instead of picking one of the many lying around .

Have you considered a windmill? Or a waterwheel? Either of those might work depending on where you are camping.

[big_dave]

It sounds like you want others to appreciate your brand of humor but are unable to accept humor from others. You threw out a whimsical idea for discussion and that's what you got. I don't see anything malicious in the discussion.

[archangle]

And as for the rock, lol, so you assume I'd be carrying rocks with me camping instead of picking one of the many lying around .

You're still going to have to lift 1000 pounds around 26 feet. And then recharge your rock supply once an hour.

you're talking about power from electronics which are notoriously inefficient,

Electronics are inefficient vs. a fan?

You think you're going to make a gravity driven portable mechanical gadget that's "efficient." SURE you are.

Before you do that, why don't you make a gadget that hooks a generator to the wheels on your car and uses it to power your engine as you drive? Or make a 150 mpg carburetor?

Although I appreciate the work put into making those calculations.

If you think those calculations take much effort, that explains a lot.

I'll take a picture of the innards,

Sure you will.

complicated check valve that would increase the efficiency even more by not pushing air during exhale,

Any energy saved by not blowing during exhale will be lost by pushing more air during inhale. You still have to keep enough pressure in the mask to treat the apnea. Unless you're thinking of making a mechanical bilevel CPAP machine.

But it was just an idea, you guys act like I was speaking blasphemy.

Not blasphemy. You just live in a universe with different physical laws than the rest of us.

[-tim]

I've had discussions about low cost DIY cpap machines for the 3rd world.

The best ideas so far involve a car heater fan in a box with a power control and a mask made from a low cost plastic dust mask and some cheap tube. It won't be quiet but it might be cheap enough. Industiral fridge fans may work too since they tend to outlast the compressors since thats what goes first. The real problem is finding a way to calibrate these things and make sure they don't provide too much power.


As far as no electricity, just use a scuba regulator and lots of tanks. They can be adjusted for a range of 0 to 10 cm. The problem is a largish tank holds 80 cu feet of air (about 2,000 liters). That is about 50 minutes per tank at my leak rates.

[naginalf]

That sounds like something that would work until you do the actual calculations.

Assume your CPAP uses about 10 watts. 1 hour of usage would be 26,000 foot lbs. If you're thinking of using a weight to power the CPAP, you'd need to carry a 1000 lb weight and lift it 26 feet to power the machine for one hour. Or a 100 lb weight lifted 260 feet.

26,000 foot lbs is an astoundingly high number, but I checked it twice.

Mechanical advantage doesn't help. Conservation of energy still applies no matter what mechanical advantage you have.

Watts converts into foot lbs. per unit time, not just foot lbs, but your point is sound. Even by my own calculations based on the average blower motor only requiring 3 watts, that's about 132 ftlbs/min., which is just as ridiculous requiring 132lbs to fall a foot every minute. Ok, that idea is out.

But what about sheer volume. I use 7psi on my machine... no that doesn't work either. I was thinking of a 1ft radius collapsible cylinder that you could pack, but 7psi over and area of 452in^2 (12^2 x π) is way too many pounds, even if I could get the volume. 0.5L breath every 2.5 seconds is 1080L over 90min and a 12" radius cylinder would need to be 66000in^3 = 452in^2 x N where N is the height, that makes it... 146inches, ok that's not too bad at 12' tall, still ridiculous.

Yup, not gonna happen. Sorry to waste your time. And I appologize for going off there, but being an arse doesn't usually make people want to listen to you and doesn't help anyone. Thankfully one of you backed it up with some science, however flawed. But anyway, thanks for going over it with me. Good to check facts against wild ideas.

[pats]

And as for the rock, lol, so you assume I'd be carrying rocks with me camping instead of picking one of the many lying around .

You're still going to have to lift 1000 pounds around 26 feet. And then recharge your rock supply once an hour.

Why lift the rocks at all? I'd pick a camp site that was already equipped with plenty of rocks complete with ready-to-use potential energy, and let them travel downhill from the camp site to convert that potential energy to kinetic energy.

[chunkyfrog]

Didgeridoo.

[akcpapguy]

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.

[JackLaBear]

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!

[-tim]

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.

I know more about the S9 than anything else....(except some antique puritan bennett ippb which uses a beautiful analog barometric computer).
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. Another could be used as a safety since its used in all their machines from most expensive to cheapest. which to me implies they are over charging but what do I know that machine cost $3,000 here and $1100 where most of you live.

Its trivial to measure pressure even if your in the most backwater 3rd world country... if you have enough water to fill a bucket. The total air volume delivered is a pain to calibrate in those conditions.

I've supplied radio gear all over the world after emergency situations. Some of those donors would love to come up with a safe device any of us could build with few tools in the worst parts of the world.

[policebox]

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