Convert AC Wall Wart Powered Illumination to Phone Line Powered LED Illumination

[markosjal]

I have struggled with this somewhat and figure there must be a sulution.

Aside from dimming circuit in Princess phones, I figure there must be an easy method for converting AC Power dial light phones to phone line powered LED operation.

The schematics I have looked at seem to lack important details like component values.

It would see logical to be able to rinky dink the Black/Yellow pair to a bridge rectifier, resistor then change out the lamp for a normal LED lamp .  Of course you may not get great brightness and may have to forgo the dimming in a princess phone.

any opinions on this?

[ThePillenwerfer]

Assuming the on-hook voltage to be 50V a 10kΩ resistor would allow 5mA to get to the LED, which is enough to operate a modern one, and hopefully not loop the line.

I think it's one of those 'try it and see' things.  Personally I wouldn't be keen as the telco could detect the current draw and think it's a fault.

[Ed Morris]

Would it matter if the phone is on a fiber optic line as the power originates on the customer side of the NIB?

[Dan/Panther]

You may want to view the information in another thread that covers very similar concerns with LED's and The Princess Phone.

D/P

http://www.classicrotaryphones.com/forum/index.php?topic=19568.msg200819#msg200819

[poplar1]

The last AT&T Princess --  the 2703BMG Signature -- had an LED dial which was line powered when the phone was off-hook. However, if a subscriber also wanted the nightlight feature, it was necessary to connect an external transformer!

[markosjal]

Princess night light aside  Trimlines only light when off hook.

Mark

[kb3pxr]

The LED circuit in the 220AL Trimline is equal to being between RR and C on a Princess or 500 series. Connecting an LED circuit between RR and C will provide line power dial lamp service. Remember, the resistor for the LED circuit is still required AND either a bridge rectifier, an inverse parallel set of LEDs (only one will illuminate), 2 pin dual color LED (color varies by polarity), or a pull from a Trimline set (Inverse parallel on one chip) is required as a polarity guard.

[twocvbloke]

Although this video is themed around "free hidden electricity", this may shed some light (badum-tish!) on phoneline-powered LED lighting:

https://www.youtube.com/watch?v=WoaLGvJkoP8

Not recommended for "emergency power" though, given a lot of "phonelines" over there are now just VoIP boxes, and soon to be even moreso given the enforced cutting of copper by the powers that be...