will it work. free power

worshrag

Member
i heard you can get a rectifier and power lamps and stuff off the 12 volt phone line. would it work in a power outage?
 

scsinet

Active Member
Ignoring the legal issues for a moment...
It would not work sufficiently to run anything tank related, and there is no guarantee that the phones will be working if the power is out, because downed poles and such would disrupt both.
These kind of ideas that you heard are pie in the sky type of stuff... you can't really extract much useful power off a phone line... if you were to study the technicalites of the way phones lines work, and the FCC part 68 rules (which are federal, making violating them potential felonies), you'd find that it's a very tiny amount of electricity. Placing a device on the line that draws too much will cause the central office equipment to recognize it as a line fault which will at best attract "unwanted attention."
If you want to try to run a tank of practically nothing, drop $20 on a solar battery charger and rip that up.
 

scsinet

Active Member
I've said it before and I'll say it again...
I try to know a lot about some things and a little about lots of things.
 

worshrag

Member
I only wanted to use an air pump on it if the power goes out. thanks though. I have another question, how does mesh mod work? how can the pump push water without the blades?
 

scsinet

Active Member
The pumps that are used in aquaria move the water via centrifugal force. The job of the impeller is to get the water roating. Centrifugal force pushes the water against the outside of the pump body, and the only place it can go is out the outlet.
So when you think about it, all the pump has to to is get the water spinning. Mesh spinning at high speed will get the water spinning. Of course, all the little bits of mesh chop the water and do a great job of mixing in air.
The thing to remember is that the modded pumps are not as efficient at moving water. Impellers are optimized to move water... mods like these move some water, but more importantly are designed to mix air efficently.
 

nordy

Active Member
Originally Posted by worshrag
http:///forum/post/2636014
i heard you can get a rectifier and power lamps and stuff off the 12 volt phone line. would it work in a power outage?
It's 48 volts as I recall and no it won't work-have you ever seen the wire gauge of copper phone lnes? way tiny wires and no reasonable current could possibly be drawn through those tiny wires, especially at those low DC voltages. running a 60W lamp on 48 volts would draw more than an amp-that's huge current on a phone line!
In the Navy, my ship had many circuits of "sound powered phones"-no amplification, just the power of a human voice vibrating a crystal, creationg voltage that would then vibrate the miniscule speaker coil. No power required so they would always work, no matter what happened to the ships systems. And, they worked amazingly well when we were in GQ in the war zone and never knew what could happen next.
 

scsinet

Active Member
FYI..
Phone line voltages are:
48 volt - Idle, on hook
~6 volts - Off Hook
90v@10hz = ring
So another thing to consider is that the voltage varies too much to be useful.
FCC Part 68 stipulates that on hook (which is the only time you'd be able to draw power), resistance must be greated than 5M over the line for the CO end to show the line as open. That's 5 million ohms. Ok so technical BS aside, at 48 volts, that means you can pull no more than 0.0000096 amps from the line. That's not enough to do anything useful with.
Far more power is delivered during an off hook state. That's 6 volts, but there is more current behind it because some phones use this power to light up dials, etc. The problem is that without a connection being made (actually talking to someone) the central office cuts the line off after a few minutes of that "da da da da" phone off the hook warning noise.
So there's a far more detailed explanation of why it won't work that anyone asked for
 
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