Forum Home
PC World Chat
Thread ID: 117831	2011-05-06 14:07:00	Phone line polarity tester	Agent_24 (57)	PC World Chat

Post ID	Timestamp	Content	User
1199946	2011-05-06 14:07:00	Just reading the latest Silicon Chip magazine, they have a project which tests your phone line polarity to see if it's backwards Apparently some routers can have a big problem with backwards polarity resulting in slow speeds although phones will work fine. Wonder if this is a common issue here?	Agent_24 (57)
1199947	2011-05-07 03:35:00	Shouldn't matter which way it's around for home use.. Some PBX systems back in the 1980s it mattered	paulw (1826)
1199948	2011-05-07 03:41:00	I think all modems have a diode bridge to solve this.	Cato (6936)
1199949	2011-05-07 15:21:00	Just reading the latest Silicon Chip magazine, they have a project which tests your phone line polarity to see if it's backwards Apparently some routers can have a big problem with backwards polarity resulting in slow speeds although phones will work fine. Wonder if this is a common issue here? Only a problem if the strings get wet.	SurferJoe46 (51)
1199950	2011-05-07 23:00:00	There must be something to it, or else they wouldn't have gone to the trouble of doing it...	Agent_24 (57)
1199951	2011-05-09 06:55:00	Just reading the latest Silicon Chip magazine, they have a project which tests your phone line polarity to see if it's backwards It's called a multi-meter.	decibel (11645)
1199952	2011-05-09 07:42:00	Yeah, but their device makes it easier to connect to the line, and it's quicker just looking at LEDs to see which way they light up and if the line is OK or not.	Agent_24 (57)
1199953	2011-05-09 09:26:00	I worked for Telecom for 21 years (from 1973) and it was possible then - and simple - to test for polarity. The faultman would just earth one or the other wire and you could see the result on the test meter back at the exchange. Polarity, in most cases, is not an issue for telephone lines, but was important for automatic party lines. Telecom has many other circuits passing through the exchanges - fire alarms, computer lines, burglar alarms - and for many polarity is important, so there is nothing new or unusual about testing for polarity. So to answer your question, Agent 24, polarity can be important for many circuits and polarity has been important for many years.	Roscoe (6288)
1199954	2011-05-09 09:53:00	Did the Silicon Chip article have any background to the "polarity problem" with ADSL modems? The Aus Standard for ADSL Customer equipment contains the following "Line polarity CE operation shall be independent of line conductor polarity. " Telecom's PTC 200 requirements include "(3) With certain exceptions (see sub-clause (4) below), all customer equipment shall continue to operate normally, and the requirements of this Specification shall be met independently of changes to the d.c. line conditions described in Section 4 of Technical Document TNA 102. Typical changes are short breaks, transient voltages, line polarity, etc. • Changes to line polarity may occur as follows and customer equipment shall not be affected by such changes:- (a) Rearrangements within the network may result in reversal of the line polarity. Customer wiring also does not necessarily maintain polarity. (b) Line reversals can occur before during or after the application of ringing and at other times during a call. (4) Some locally powered devices are dependent on a particular line polarity (e.g. some PABXs, etc) for correct operation. This requirement shall be made clear to both customers and installers, and the matter will need to be discussed between installers and local Telecom staff at the time of installation. " My bolding.	PaulD (232)
1199955	2011-05-09 10:39:00	Some devices have a telepermit sticker attached. Or not. My Thomson ADSL modem has one and I guess it cares not about Polarity as it seems to work.	Snorkbox (15764)
1 2