battery bolts

[StarTech]

Normally telephone are operated at -48 VDC with the phone sending a 20Hz 105 VAC signal along the line to ring the phones The negative voltage use to prevent the phone wires from corroding.

Fiber optics is changing this.

 

[AdamE]

Normally telephone are operated at -48 VDC with the phone sending a 20Hz 105 VAC signal along the line to ring the phones The negative voltage use to prevent the phone wires from corroding.

Fiber optics is changing this.

Yeah, POTS lines use 75 vac minimum for the ringer.

 

[WaltWorld]

in my area 40 years ago ringing current 110 volts pulsating DC. Old phone man

 

[SeniorCitizen]

Being we've wandered way off topic from BOLTS to VOLTS, what volts did the telephone we had generate? We could answer it or take it fishing.

 

[bertsmobile1]

The post WWII system used in OZ was 50 V DC
Dad finished his working life as an exchange cleaner for the GPO.
One of his jobs was to top up the batteries in the battery room and wax the walls & floor to protect them from the excessive humidity
These were open toped glass battery cases in lines of 25 single 60 plate 2 volt cells so when they were getting old the battery technician could simply pull the busbar up & replace the worn out plates .
During the 90's they were all replaced with sealed maintenance free cells and the old glass battery cases ended up in antique & decorator shops labled as "antique acid storage jars " because the glass battery case had the words "acid level " on all 4 sides and a pouring lip on both short side so the old acid could be poured out cleanly before the cases were washed & returned to the racks .