Connecting a CPAP machine to a battery?
I have been prescribed a CPAP machine for Obstructive Sleep Apnea. How do I run this while traveling if I don't have a generator or battery? I am thinking of buying a portable jump starter like thi...
Forum Discussion
pnichols wrote:Sam Spade wrote:
Sorry but they don't "do the same thing" at all.
The external ferrite bead does NOTHING to voltage variations or long period "spikes". They are there for RF suppression.
Chokes typically are in series with a power source and do various things, depending on the design, value and application. RF suppression of only one application for them.
Depending upon what frequency one is talking about relative to voltages that are varying (i.e. not DC voltages) ... they both "do the same thing".
Chokes are usually used to dampen out lower frequency voltage variations/disturbances and ferrite beads are usually used to dampen out higher frequency voltage variations/disturbances.
However, I've seen plenty of radio frequency circuits that were using small air-core chokes to dampen out or eliminate unwanted radio frequency disturbances.
Read up again on descriptions describing what ferrite beads are used for and you'll see the word "choke" - used interchangeably with the phrase "ferrite bead" - appearing quite a bit. The main difference in when to use one or the other has to do with the frequency of the unwanted electrical energy that one wants to control.
I haven't cut open the little plastic cylinder in my CPAP machine's power cord to see if it's a small choke or a ferrite bead inside but it could possibly be either, depending upon what type of voltage spikes that the designers wanted to keep from entering the machine.
having been involved in the design of modern power supplies and regulatory requirements, very often chokes, ferrite beads, whatever you want to call them, were used not to dampen any incoming power line spikes, but to dampen internal RF from going back OUT the cord and into the line and violating part FCC part 15 specs or other regulatory requirements on stuffing **** back into the power line or radiating RF to surrounding devices.
Internal design was robust enough to take very high level spikes and interference without any side effects or damage.
