Let me just chime in regarding on how to connect two analog phones or modem/fax in the simplest way.
The voltage at a common european telephone network during an established connection is around 12V.
4.5V are enough to bridge short distances up to 20meters.
No matter which analogue telephones are used, there is no need to limit the current in the below mentioned
simplest possible telephone or modem/fax connection, because the power can be inserted in series to the line.
The ac voltage for analogue bell ringing is 48V.
Pulse dialing means to short the telephone completely for the number of pulses dialled.
The normal power feeding in the old pulse dial times was to feed the line via two relais which had been used also to
transmit the dialing pulses to a special electromechanical connection device.
So the shortcut during pulse dialing would definitely force the relais to hold and release afterwards.
Nevertheless in my opinion it is much more comfortable to use the (in many cases) already existing home telephone switchboard.
Cheers
Johannes
-----Ursprüngliche Nachricht-----
Von: Marco Mailand [SMTP:Newton2k1_at_mac.com]
Gesendet am: 28 September 2001 13:05
An: newtontalk_at_newtontalk.net
Betreff: Re: [NTLK] Newton scanners?
> 48V?
That's what I measured on our Swiss landline analog wall outlet. ISDN uses
100V (which I haven't measured yet :-).
> That was 7.2V, and there were lines of over 200ft.
> No problem. You don't need routing if it's only your modem and your fax
> machine on the line... you just need to insert some power.
However, the batteries would be able to deliver some Amperes, at least about
1...2A which should be current limited, I think, because some of the
equipement is using current loops to perform dialing and the like. At least
the elder pulse phones in EU did, new have probably much less power
consumption and have their own internal series resistance.
I'll try that idea but with a current limited power source. Thanks!
-- With best regards / Viele GruesseMarco Mailand http://slsbd.psi.ch/timing
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