(10-08-2014, 09:12 AM)Sumwhatinterested Wrote:(10-08-2014, 08:28 AM)justMongo Wrote:Good Morning(10-08-2014, 05:39 AM)Sumwhatinterested Wrote: Hi Mongo,
I connected the S8 to 12 volts to try it out because it has a normally 12 volt plug pictured on the Resmed adapter. I learned later that the center pin is negative unlike most automotive accessories. May I ask where or how you determined that the S8 DC input is 24 volts?
Thanks for the reminder, I guess I forgot my basics.
But now I see another way to post a picture of the board in question, because of your reply.
Thanks for your effort.
I'd like to see the component location your referring to.
An S9 runs off 24 VDC for both the blower unit and the humidifier.
The S8 uses the AC voltage to heat the humidifier. It has an SCR that is pulse modulated to control the heater plate.
The designer may have relied on the plug to protect against reverse polarity.
I would have protected it with a pair of Schottky diodes -- low forward drop.