|
Posted by PrecisionMachinisT on July 14, 2005, 9:20 am
>
> >>
> >> Care to explain to us in detail these so-called 'different electrical
> >> characteristics' ???
> >>
> >> ( IOW, I call bullshit.... )
>
>
>
> Thee are some differences in plugs, at least
>
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=5788083200&category=58360
&ssPageName=WDVW&rd=1
>
>
> And in how they ring
>
http://electronics.howstuffworks.com/framed.htm?parent=telephone.htm&url=htt
p://www.hut.fi/Misc/Electronics/circuits/telephone_ringer.html
>
> What is ring signal ?
> The telephone company sends a ringing signal which is an AC waveform.
> Although the common frequency used in the United States is 20 HZ and in
> Europe is typically 25 Hz, it can be any frequency between 15 and 68 Hz.
> Most of the world uses frequencies between 20 and 40 Hz. The voltage at
the
> subscribers end depends upon loop length and number of ringers attached to
> the line; it could be between 40 and 150 Volts. The ringing cadence - the
> timing of ringing to pause - varies from telephone company to company.
>
> What telephone regulations say about telephone ringers
> European NET4 telephone line terminal equipment specs define the following
> specs for the telephoen ringing detector circuit.
>
> a.. The impedance in voice frequency (200-3400 Hz) must be greater than
10
> kohm when measured with 0.5V RMS audio signal
> b.. The current taken by the ringer must be equal or less than 5 mA at
35
> V ring voltage and equal or ledd than 10.7 mA at 75V ring voltage. The
> measurments are made using 25 Hz ring current frequnecy.
> c.. Ring detector must work on ring signal which is 44-58V DC summed
with
> 25+-3Hz AC ring signal in voltage range 35-75 V. The feeding resistance
for
> ring generator is 800-1710 Hz.
> d.. Ring detector must not detect ring signal which is 44-58V DC summed
> with 20-3400 Hz AC ring signal which is less than 10 V. The feeding
> resistance for ring generator is 800-1710 Hz.
> If the equipment is automatically responding the equipment must wait at
> least 1s from the ring detection until it goes off-hook.
>
> Telephone ringer classification
> In USA FCC regulations need the ringer type to be specified on the device.
> The possible types are Class A and Class B. Class B ringers will respond
to
> ringing frequencies of between 17 and 68 Hertz while Class A ringers will
> respond to betwwen 16 and 33 Hertz. Class A devices are those typical old
> telephone bells and practically all electronic ringers are B type. Nearly
> all of the devices made to connect to the phone lines today are of the
Class
> B type. The telephone ringer type on your device (if you live in USA) is
> printed on the FCC sticker on the bottom with a REN number on it. You'll
see
> something like .9B (= REN 0.9 Class B) or 1.0A (= REN 1.0 Class A).
>
>
Ed,
Forget Europe for now, Pop had said "pay phones" have different electrical
characteristics than "regular phones".
His claim, so its up to him to explain the difference between the two, if
any........
--
SVL
| 
Yahoo! 
Google 
Windows Live 
del.icio.us 
digg 
Netscape 
XML Sitemap