Polarity on 12 volt DC plug

Could someone measure the polarity of the DC cord used on a REMstar Plus Domestic for me please. I have several cords from my amateur radio stuff that will work but I can't find reference to the polarity for the cord. I would think the standard is + positive on the center pin which is the way my cords voltage reads. I have 3 of them with the fuse in the barrel of the power connector (quit smoking so I'm using and more politically correct term).

Thank you, Bob Smith
p.s. How do you get those cute pictures beside your posts????

From memory it is + in center pin (we have many threads discussing this - try a search with args 'Respironics dc polarity'

Resmeds are reverse to Respironics & have -ve center pin.

DSM

(but this needs confirmation before taking it as gospel )

I am assuming the ham couldn't find his meter, and confirming that my Respironics A/C > DC plug has a positive center pin = +12v @3A
Parts are avail at Radio Shack for those who don't have them.

Thanks for the confidence GumbyCT.. Actually, the DC plug has a + positive center coming from my power sorce. What I can't find is proof of the polarity of the socket in the back of my REMstar Plus. Nothing in the manual, nothing noted on the back of the machine. I needed the information about the DC input to the back of my unit before I plug a battery into it. Maybe I can find a service manual or something to do with the wiring. At this point I'm 98% sure the center is positive.

Thanks all,
Bob Smith WB6ODR, Prescott, AZ

Bob Smith wrote:Thanks for the confidence GumbyCT.. Actually, the DC plug has a + positive center coming from my power sorce. What I can't find is proof of the polarity of the socket in the back of my REMstar Plus. Nothing in the manual, nothing noted on the back of the machine. I needed the information about the DC input to the back of my unit before I plug a battery into it. Maybe I can find a service manual or something to do with the wiring. At this point I'm 98% sure the center is positive.

Thanks all,
Bob Smith WB6ODR, Prescott, AZ

Bob, I just told you. This IS the plug that comes with the machine. The wall plug converts to +12v.

GumbyCT wrote:I am assuming the ham couldn't find his meter, and confirming that my Respironics A/C > DC plug has a positive center pin = +12v @3A
Parts are avail at Radio Shack for those who don't have them.

Thanks a million GumbyCT.... Didn't realize that is where you were measuring. Now for my next trick I'll look into the software I've seen talked about on this forum. Sure hope you machine is helping you as much as my help me.

See you later. Bob Smith

The software won't be of use with the PLUS, they are low end units that collect no useful data. Jim

dsm wrote:Resmeds are reverse to Respironics & have -ve center pin.

Not so sure about that. I think that the majority of Resmeds models have also a positive center pin with the exception of a few earlier models. It is important as if you use reverse polarity that could lead to major problems (some newer models have now systems that even protect against reverse polarity).

Now that I've beat up my REMstar Plus I have been studying other xPAP machines and think I need a new one.... Technology has made giant leaps in the 6 years I've been using my machine. I really like the new machine with built in humidifiers and software. Leaning towards the DeVilbiss IntelliPAP Auto Adjust CPAP System. I can make a battery pack for it the few times I need complete portability. Thanks to all for your polarity input.

Bob Smith, Prescott, AZ

Bob Smith wrote:Now that I've beat up my REMstar Plus I have been studying other xPAP machines and think I need a new one.... Technology has made giant leaps in the 6 years I've been using my machine. I really like the new machine with built in humidifiers and software. Leaning towards the DeVilbiss IntelliPAP Auto Adjust CPAP System. I can make a battery pack for it the few times I need complete portability. Thanks to all for your polarity input.

Bob Smith, Prescott, AZ

I have the DeVilbiss Intellipap Auto machine. According to the CPAP.com site, the 12v DC battery cord that fits your REMstar will fit the Intellipap also. I just built a cable for my machine and it is indeed positive center on the plug.

Since you are considering the Intellipap Auto machine I thought I would mention that the machine will automatically switch from AC to DC power if the AC power goes out. That way you can run it on AC but have the battery plugged in as backup in case your power goes out. I have tested it and it switches back and forth flawlessly without interruption to your therapy. The heated humidifier of course turns off when it switches to DC power but it turns back on again when the AC power is restored.

Maybe other machines work this way too. I do know that the Respironics M-Series does not have this switching ability since it runs off a 12V AC to DC power brick. Of course you can now get a version of the M-Series heated humidifier that runs off of 12V DC power so if you want heated humidification when on battery power (and you have a big enough battery) then the M-Series might be the best choice.

apnez wrote:

dsm wrote:Resmeds are reverse to Respironics & have -ve center pin.

Not so sure about that. I think that the majority of Resmeds models have also a positive center pin with the exception of a few earlier models. It is important as if you use reverse polarity that could lead to major problems (some newer models have now systems that even protect against reverse polarity).

Hi

This one had a -ve center pin. Which ones did you check ?
http://www.internetage.ws/cpapinfo/s8-12vdc-1

Cheers

DSM

dsm wrote:

apnez wrote:

dsm wrote:Resmeds are reverse to Respironics & have -ve center pin.

Not so sure about that. I think that the majority of Resmeds models have also a positive center pin with the exception of a few earlier models. It is important as if you use reverse polarity that could lead to major problems (some newer models have now systems that even protect against reverse polarity).

Hi

This one had a -ve center pin. Which ones did you check ?
http://www.internetage.ws/cpapinfo/s8-12vdc-1

Cheers

DSM

From the pictures I would say that has a positive center pin. There's a red wire going to a factory style plug. That most likely means the red wire to the center pin. The positive wire on the cigarette adapter plug is most likely the all black wire. Most of the adapters that use that color scheme (black and black w/white stripe) use the white stripe to signify negative. I've dealt with a lot of those cig lighter adapters.

I cut the wire from the cig lighter plug to reverse it ! - how else do I need to explain it ?

DSM

#2 Let me put it another way, that is my hand, my cpap (since sold) & my car in the photos. I think I know what polarity made it work
(add to that - I was originally trained as an electronics engineer)

dsm wrote:I cut the wire from the cig lighter plug to reverse it ! - how else do I need to explain it ?

DSM

#2 Let me put it another way, that is my hand, my cpap (since sold) & my car in the photos. I think I know what polarity made it work
(add to that - I was originally trained as an electronics engineer)

I stand corrected. The guy who actually owns one and has made the cable wins.

dsm wrote:#2 Let me put it another way, that is my hand, my cpap (since sold) & my car in the photos. I think I know what polarity made it work

Mine is the same, -ve centre.

dsm wrote:(add to that - I was originally trained as an electronics engineer)

And snap to that too...