Re: telephone line as power
Hi,
Your telephone line gives 48V DC in open loop condition, i.e., when you do not draw any current from it. Normal telephone lines are rated to provide only 20mA of typical current while the telephone is in offhook state with a typical terminal voltage of around 12V for the telephone. This means the internal resistance of the telephone line is around 1.8K Ohms (48-12)/20*10-³.
Your filament lamp when it works at 1W at 3V will need 330 mA of current, which means it will have only a hot resistance of about 9 Ohms and its cold resistance will be almost zero. When you connect such a low resistance to your telephone line, you will get only milliVolts across the lamp ( 20mV if the lamp has one Ohm) and it will not be sufficient to light up the lamp. Please observe the line voltage when you connect the lamp across it, using a multimeter.
Regards,
Laktronics.