Flashing Lamp Ring Indicators

[poplar1]

Page 27 of 502-501-115, Issue 1 shows a standard message waiting set using an ordinary neon lamp connected in series with a standard 27K resistor. 

Thanks. That's interesting and would be easy to bench test with a ring generator, a lamp and a resistor. Seems my memory was off in that the lamp only flashed while the ring voltage was present, 2 seconds. Thanks for providing the schematic. Very useful, indeed.

The lamps in 500Y sets and others are *message waiting lamps.* The fact that they light up during the ring cycle was not their primary purpose.

[TelePlay]

Well, got out a few things and bench tested the circuit and it works as expected. Put a 120 VAC neon lamp in line with a 20 HZ ring generator using a 26.7 K resistor. The lamp flashed at 20 HZ, not the slower flash rate expected from a PBX or similar system. The lamp was not bright enough to gain attention. Changing resistance to 22 K did not change intensity.

[G-Man]

They naturally flashed during the ringing cycle however a slower flash (or blinking) was achieved by circuitry installed at the PABX or manual switchboard and not inside of the telephone.

The operator or attendant would activate it when a message was left.

[allnumbedup]

My project is to mount a LED under a vintage jewel-type cover from a amplifier in order to complete a GA-51859 (TA236/FT) Signal Corps 500 phone that was a two line phone and has an empty drill hole for the missing switch.  Similar to the discussion in this older thread, I want that light to be a flashing call indicator---but 20hz is just fine.

I found a 1990's $2 thift store phone with an LED ringer. When I place the LED in series on the green TIP line before it gets to the network and connect the red RING line to the network, I get what I think is a good result:  The led flashes with ringing and when you lift the switch hook to talk the LED goes to constant on and then off when you hang up.  I notice that the LED also 'dings' when I dial.  Transmission seems good without buzzing or a decrease in sound level. I have not changed the connector for the C4 ringer which remains connected to L1 and L2 and across K.

Three questions:

1. Can I sweat off the LED from the circuit board along with the little resistor in parallel to the LED leads and have it work or is there something else on the circuit board providing function? (Next to the LED is a switch which is not hung up for this test with the alligator clamps.  The board as three switches: ringer volume, receiver volume, and Tone/Pulse selection, pizo ringer, and a strip to the keypad.)
2. Is the LED creating an open line so that there is a better way to place it in series with the ringer--like more effectively using the switch hook leads?
3. If the LED eventually fails or burns out would the phone lose service?

The thrift store phone  base is bigger than the handheld part but the base only contains a modular RJ11 jack , two wires, and a RF22 jack so that all the functional components are in the handset and the base is only there to carry everything  from the plug in the base up to the handset. "Progress" I guess