Possible to wire a Commtel phone guard to mains?

daveinmanc

Hello folks, newbie to the forum but not to attempting to save a few quid

I have a commtel phone guard which works perfectly well and am very pleased with but it has one minor/major flaw . . . power supply, which is provided by 2 3v button/disc type CR2450 batteries. Obvious flaw is that when the batteries go flat it doesn't work . . . .so . . . is it possible to get some sort of voltage regulator so i can draw power from the telephone wiring which is somewhere around 50v and reduce/regulate it to 6v?

Or, any other bright ideas for a power supply that would mean i can dispense with the batteries ??? Could i use a 6v DC mains adaptor to do this ? It's the only thing that lets an otherwise very clever product down . . . . . .

thanks in advance

Owain_Moneysaver

daveinmanc wrote: »

Hello folks, newbie to the forum but not to attempting to save a few quid

I have a commtel phone guard which works perfectly well and am very pleased with but it has one minor/major flaw . . . power supply, which is provided by 2 3v button/disc type CR2450 batteries. Obvious flaw is that when the batteries go flat it doesn't work . . . .so . . . is it possible to get some sort of voltage regulator so i can draw power from the telephone wiring which is somewhere around 50v and reduce/regulate it to 6v?

Or, any other bright ideas for a power supply that would mean i can dispense with the batteries ??? Could i use a 6v DC mains adaptor to do this ? It's the only thing that lets an otherwise very clever product down . . . . . .

thanks in advance

1. No - you'd probably draw too much current from the phone line and your phone would be permanently engaged

2. Absolutely not - if a fault occurred with the mains adapter then mains voltage could be put back on the phone line possibly causing damage to the exchange and injuring someone working on the line at the time.

You could fit an external larger 6V battery, which should last for absolutely ages.

I presume you've checked that the 3V batteries are in fact in series to give 6V.

Buzby

Only the ring voltage is 50v, when the current is applied during the ring phase, after that - it's a minimal voltage to keep the line looped and the call in progress. I'd forget trying to take power from the line, it's fraught with issues. I wouldn't say it is an a flaw of nature that batteries go flat - more the laws of physics. You should get at least 6 months from a fresh set of cells, often longer.