Eliminate 60 cycle hum from phone connected to Obi
ProfTech:
I know this has been discussed lots of times and it mainly applies to Obi 110 but not entirely. Certain phones connected to any Obi may experience a noticeable [even horrible] 60 cycle hum/buzz due to the "Switching" power supply that is included with the Obi. I found a Jameco 120 volt linear 12v regulated supply that works great and eliminated the buzz. Be aware that it costs about $25 dollars, weighs about 1 1/2 lbs and pulls about 22 watts so won't run cheap. But it does fix the hum problem. Several numbers on the box "Part number 170245", "PWS-37-ACDC", & "DDU120100H4480". I ordered mine from AttBatt.com under the DDU number.
dircom:
I wonder if a 12V UPS battery would work?
I have a spare UPS I might try it, just need to recharge it occasionally
bonus no 24x7 energy usage waste, and no power surges
isolation from A/C power
ProfTech:
I considered using a battery but didn't have anything to try. Should work fine except I wasn't sure of a good / inexpensive way to keep it charged. I figured a small battery should run the Obi 1 to 2 days but as the voltage drops you might have an issue if it goes below (unknown number). I used a Netgear supply for a few days that was better but its voltage was 14v or a little more so wasn't sure if that was a good idea. Didn't smoke the Obi but I took it off anyway. I'm considering putting the Jameco on a simple timer and shutting it down from 10PM to 8AM. Side benefit no bogus calls after 10 PM! I also tried a standard 110v UPS but I was running the Obi off the "Filtered" side because I didn't have a battery. Still heard the buzz and they want about $60 for a battery for this UPS. :(
dircom:
I forgot, I picked up a couple of what looks to be wheelchair batteries at a thrift store. Will hook one up, and periodically test voltage drop
but I would need to add a switching step up/step down dc/dc power regulator
SteveInWA:
Why not buy it directly from Jameco for $14.95? You got robbed.
http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?search_type=jamecoall&catalogId=10001&freeText=DDU120100H4480&langId=-1&productId=170245&storeId=10001&ddkey=http:StoreCatalogDrillDownView
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