A buddy of mine bought a small house in the middle of nowhere , mains power was disconnected at some point , he's planning to live without the creature comforts or standing charges associated with mains supply . There is however a phone line remaining connected to the exchange , most likely supplied with 50 or so volts dc . He has a bank of 12 volts gel cells which he needs to dismantle and take to a friends place to charge every once in a while ,its just to run led lights and a small invertor for low wattage 240V appliances like mobile phone charge etc
From a recent previous discussion about telephone mics I found out a single old style carbon mouthpiece could draw upto 100ma at 50 volts , in the event of two recievers off the hook thats 200ma potentially . A trickle charge of 200ma at 50 volts across four lead acid 12volt batteries would do nicely to keep things topped up .
When I mentioned this potential source of power his eyes lit up , lets set any possible legal implications aside and consider if this is feasible , would a simple resistance in series limit the current to a reasonable amount and still keep the batteries topped upto 12.8 or so volts? Of course the man in the telephone exchange may notice the voltage drop if he comes along with his meter to the local connection box ,but more than likely he'll think its bad insulation due to moisture ingress into the cableing . Inevitably the phone supply is made to withstand an almost dead short although the resistors in his junction box might be running a bit hot ,ahahahaha
Tomorrow I may perform some load tests on my own redundant land line just to see whats possible current wise ,of course out in the back arse of nowhere you've potentially miles of cable so things might well be different .
From a recent previous discussion about telephone mics I found out a single old style carbon mouthpiece could draw upto 100ma at 50 volts , in the event of two recievers off the hook thats 200ma potentially . A trickle charge of 200ma at 50 volts across four lead acid 12volt batteries would do nicely to keep things topped up .
When I mentioned this potential source of power his eyes lit up , lets set any possible legal implications aside and consider if this is feasible , would a simple resistance in series limit the current to a reasonable amount and still keep the batteries topped upto 12.8 or so volts? Of course the man in the telephone exchange may notice the voltage drop if he comes along with his meter to the local connection box ,but more than likely he'll think its bad insulation due to moisture ingress into the cableing . Inevitably the phone supply is made to withstand an almost dead short although the resistors in his junction box might be running a bit hot ,ahahahaha
Tomorrow I may perform some load tests on my own redundant land line just to see whats possible current wise ,of course out in the back arse of nowhere you've potentially miles of cable so things might well be different .