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[Equipment] Alternate power supply
#11
RE: Alternate power supply
Hello Ralph, In my original reply I was keyed into the concept of your using AC as your ultimate source.
That was how I glommed onto the sine wave idea.
Anyhow, if you are using DC only, you might want to bread board a temporary set-up using potentiometers to
get your DC output voltage as close as possible to those obtained from the original ResMed equipment. I think, if
you are able to match the ResMed voltages and it still doesn't work, then I would wonder if there are switching
transistors in your DC to DC power supply causing a sufficient amount of ripple to cause rejection of the applied power.
I too was an Electrical & Instrument Fitter, but in the USN.
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#12
RE: Alternate power supply
If I could get into my workshop it might help, but at the moment I am stuck doing the odd job in the kitchen, which does not go down well at all with the other half.   Rolleyes 
Solder has this habit of making tables turn brown when flux drips off with the solder onto the table.
I was careless enough to let some drip off the paper I had open to avoid just such an event, so there is now a ban!
I will have to wait until the summer so I can clear my workshop out before I can do any work in there.   Oh-jeez
I am NOT a doctor.  I try to help, but do not take what I say as medical advice.


Every journey, however large or small starts with the first step.

Sleep-well
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#13
RE: Alternate power supply
(02-22-2018, 12:46 PM)sylvan Wrote: Hello Ralph, In my original reply I was keyed into the concept of your using AC as your ultimate source.
That was how I glommed onto the sine wave idea.
Anyhow, if you are using DC only, you might want to bread board a temporary set-up using potentiometers to
get your DC output voltage as close as possible to those obtained from the original ResMed equipment. I think, if
you are able to match the ResMed voltages and it still doesn't work, then I would wonder if there are switching
transistors in your DC to DC power supply causing a sufficient amount of ripple to cause rejection of the applied power.
I too was an Electrical & Instrument Fitter, but in the USN.

The mod I am working on involves this little item, which is the size of a SIM card.
   
It will take a DC voltage between 3.7v and 5v and output a stable 3.3v. It cost the princely sum of $2.39 (postage free) from China.
Unfortunately the lead time to Australia is always 4 to 8 weeks, but as I've said, there is no urgency for this project.
I do believe this will work when I couple up 3 AAA batteries and it will all fit in my in-line container (pill bottle), so be quite neat.
I don't believe the 24v supply will be the problem, any smarts are going to be on the signal wire.
A challenge like this is good.....it gets the grey matter working.

ps Sorry to hear Sleep2Snore has to hibernate in winter and not use his shed. But I do understand the hazards of solder!
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