"The phone is a remarkably complex, simple device,
and very rarely ever needs repairs, once you fix them." - Dan/Panther

Main Menu

Help, Mr Wizard, oby wan, dsk, or anyone wants to splain JUMPIN batt current

Started by RB, March 10, 2019, 05:11:05 PM

Previous topic - Next topic


So, I am wrappin up my Local Batt phone network installation, and lookin for a suitable power supply.
My cord board supplys the DC power to all the phones "8" via the yel and blk wire in line connection.
5v dc at 3 amps
Connecting an extension to the Board "operator" works ok.
connection 2 extensions together works ok.
Connecting an extension through the cord board, through an iso transformer to my 616 works ok.
Back to the post:
I am lookin at a Miliamp meter I put in line with the 5v dc power supply.
I lift a leich 901 and the meter pegs, then hovers somewhere between 12 and 22 ma. AWESOME!!!
I talk into the transmitter, and the needle jumps between 22 and 35 ma there abouts.
Then, I move the coil handset cord, and the meter jumps between 12, and 45+ ma...WTFish????
So, I get another leich 901...same thing.
I grab a 315 wood box, and same thing!!!
Now I am getting hacked...wutz goin on here?
So, I switch to Batts, SAME THING!!!
Now, I remove the board, and power the phones up with batts and the inline meter, and SAME THING!
I know coil cords can change resistance with stretching, but a straight cord did it also, and a 20 ma plus current swing?
How can you avoid over current conditions???
If I can't keep the phones current draw under 40ma with batts, how can you possibly compensate with a wall power supply?


Moving the handset changes the resistance just like talking. It might help to insert a choke or  series light bulb in series with the power supply to limit the current