[GreenKeys] Another question for old Bell System guys

[Jim Haynes]

On Tue, 16 Dec 2008, Larry Tighe wrote:

> Jim,
>
> Where did the 130 VDC come from?  I've only seen the huge 48 VDC battery 
> banks and the 80-120 VAC 20 cycles for ringing.  I do remember 130 VDC for 
> the coin collect/return relays in payfones...did it come from inverters???
>
Usually rectifier and storage battery plant - used in offices where there
were vacuum tubes needing plate supply, and I guess also as telegraph
battery.

In one small office I'm aware of there was a rectifier and the backup 
battery was made of #6 dry cells.