| ??? 07/20/07 15:53 Modified: 07/20/07 15:55 Read: times Msg Score: +1 +1 Informative |
#142088 - I faintly recalled something about electrolysis... Responding to: ???'s previous message |
.... or corrosion.
But now I found this: wikipedia said:
Telephone exchange communication equipment, such as DSLAM, uses standard -48V DC power supply. The negative polarity is achieved by grounding the positive terminal of power supply system and the battery bank. This is done to prevent electrolysis depositions. And [sligthly later] also this: http://www.piclist.com/techref/pots.htm said:
Tip and ring get their name from the construction of an operator's plug-board plug -- tip was the tip, and ring was the ring below the tip. The positive voltage (ground) was put on the tip line, because that was the part of the plug that the operator had the least chance of touching. negative battery supplies (with respect to ground) have always been used with phone systems, so that leakage currents to ground caused by moisture do not electroplate away the copper in the wires. JW |
| Topic | Author | Date |
| another Weekend Way Off Topic | 01/01/70 00:00 | |
| Electrolytic effects - and further off-topic... | 01/01/70 00:00 | |
| I faintly recalled something about electrolysis... | 01/01/70 00:00 | |
| And whath about older cars "plus"-ground? | 01/01/70 00:00 | |
| maybe the same reason... | 01/01/70 00:00 | |
| Try an alternate form of the question. | 01/01/70 00:00 | |
| What's in a name? | 01/01/70 00:00 | |
| references | 01/01/70 00:00 | |
| Hanging ground straps | 01/01/70 00:00 | |
| Another possible use for hanging ground straps | 01/01/70 00:00 | |
| No contact while driving | 01/01/70 00:00 | |
| ECL chips use positive grounding | 01/01/70 00:00 | |
| Going way - way off - off topic | 01/01/70 00:00 | |
| Car tyres conduct | 01/01/70 00:00 | |
ground straps | 01/01/70 00:00 | |
| Upside down... | 01/01/70 00:00 | |
| after 2 hours googling | 01/01/70 00:00 | |
| It is for corrosion | 01/01/70 00:00 |