How many dial lighted phones can a 5VDC dial light transformer support ?

[RotoTech99]

Dear Forum:

I was asked about how many Trimline or Princess sets a 5VDC,160mA dial light transformer would support by a neighbor who has a number of Trimline with incandescent dial light he'd like to run off of that, plus one Princess set.

I told him I know what the BSP's say for the 2012A/2012C transformer, but for DC ones,I don't know.

I know though the BSP for station transformers that a 2012A/2012C dial light transformer can support any number of trimline plus one Princess per residence, and that Princess sets require their own separate dial light transformer, particularly if multiple Princess sets are used.

Please does any forum member know what would be the allowable number of Princess or Trimline sets he could run from a 5VDC, 160mA transformer? Additionally, what would be the allowable number of Princess or Trimline that could be run from a DC transformer of similar volts and amps used to light dial light phones?

All assistance and advice would be appreciated with Thanks.
Rototech99

[unbeldi]

Quoting from already existing posts on the Forum:

The light bulb in the Princess was powered by a Western Electric No. 2012A or 2012C transformer.  It was a simple A.C. transformer for 105-125 V  60 Hz,  with a secondary winding that output 6-8 V delivering 0.25 Amps or 1.75 VA.

These transformers had a very high internal impedance of 50%, and could withstand short-circuits. When shorted they drew only 0.5 A.

You can use any transformer or DC power supply that provides 6 to 8 volts and a quarter amp.



http://www.classicrotaryphones.com/forum/index.php?topic=16134.msg167100#msg167100
http://www.classicrotaryphones.com/forum/index.php?topic=15418.msg160166#msg160166
http://www.classicrotaryphones.com/forum/index.php?topic=14872.msg154362#msg154362
http://www.classicrotaryphones.com/forum/index.php?topic=13281.msg139265#msg139265
http://www.classicrotaryphones.com/forum/index.php?topic=10224.msg108742#msg108742

So the answer to the question is that your supply is not sufficient to correctly power even a single Princess lamp.  It will glow, sure, but the supply will technically be overloaded.

[RotoTech99]

Dear Unbeldi:

Thank you for the information; the 5VDC, 160mA one i'm using with my Princess does nicely.

As to my neighbor, if he sticks with the DC dial light adaptor, what is the voltage and milliamp range that would let him safely do what he wants to do?

Personally, I would tell him to use a 2012A or 2012C, but as he asked me to look into his original question, i thought i should get him that info first.

Rototech99

[Jim Stettler]

WE did make an apartment house transformer for multiple "lighted dials". ISTR that it has a 6 and an 8 volt tap.
JMO,
jIM s.