From: Groepaz (groepaz_at_gmx.net)
Date: 2004-01-30 14:21:57
On Friday 30 January 2004 13:52, Marko Mäkelä wrote: > A semiconductor or an inductive or capacitive load can be viewed as a > voltage source. Maybe Mr. Levak was referring on that? mmmh ok, maybe :=P > Has anyone measured the voltage when doing pulse dialing? I think that > there can be high spikes. In the early 1990s, when I used a 2400 bps modem > (the only modem I have ever owned and still own), I remember seeing garbage > on the screen that could have been caused by a neighbour calling with pulse > dialing. I also remember hearing dial pulses when talking on the phone. > Back then, the phone exchange didn't understand touch tone dialing (or it > did, but it apparently internally converted DTMF to dial pulses, because > DTMF calls were actually slower to connect than pulse dialed calls). pulse dialing is nothing else than interrupting the on-hook voltage for a defined period of time (thus the dialer in the phone is called "interrupter"). the spikes come from the fact that the interrupter infact toggles the phone beeing on-hook and off-hook, which means connecting and disconnecting the bell from the line => inductive load here ... resulting in spikes :) you can easily prove that to yourself by "dialing" using just the hook...mmh or maybe that doesnt work anymore on modern lines :) it was a neat trick in certain countries to dial with the hook in public phones... *cough* :=P gpz Message was sent through the cbm-hackers mailing list
Archive generated by hypermail pre-2.1.8.