Author Topic: 555 pbx cord set questions  (Read 225 times)

Offline RB

  • ***
  • Posts: 235
555 pbx cord set questions
« on: September 25, 2017, 10:04:12 AM »
Hi
RB here with a question about this cord set.
it is from the : General system practices Section 503-620-400 issue 1 Dec 1965 GT&E standard 555 pbx
I have one cord set from a 555 board. it is labeled:  J59013 E4 L6 B
I found this schematic, but it is too poor to read clearly.
So, I have cleaned it up a bit, and extracted everything that is not connected directly to the
Tip, Ring/ and sleeve in the idle state. meaning, nothing is touched.
I did this to remove the clutter, and will re insert the remaining part of the circuit when I get this part down.
in the image cordset edit T and R only, in the upper left portion, there is a retard coil placed across the T and R when the "T" relay is engaged. it contains two small parts referred to as
Fig J, and Fig K. they complete this circuit, but I cannot see exactly how they are wired.
First question : can you tell me the purpose for this retard coil in the circuit, and how to complete the drawing?
Second question : is there a clear copy of this schematic available?
and can you provide a link? my search skills leave much to be desired.
I want to be correct with my drawings.
Thank you.

Offline trainman

  • ****
  • Posts: 471
Re: 555 pbx cord set questions
« Reply #1 on: September 25, 2017, 09:51:11 PM »
I cant read the schematics clear either. Usually a retardation coil is used to keep DC current out of some part of the circuit.

Offline RB

  • ***
  • Posts: 235
Re: 555 pbx cord set questions
« Reply #2 on: September 26, 2017, 08:41:08 AM »
Thank you trainman!!! :D
outa 29 views, you are the only one to comment... ???
The schematic came from here somewhere.
And yes, it is pitiful at best.
Thats why I am trying to fix it... That is, if i can get folks to share some wisdom.
Then we maybe could all benefit from the effort???

Offline HarrySmith

  • Hero Member
  • *****
  • Posts: 4304
  • 1956 Rose Beige 500
Re: 555 pbx cord set questions
« Reply #3 on: September 26, 2017, 08:59:52 AM »
I have a ton of 555 documents online. I am sure what you need will be in there. They are stored on Google drive, I do not know if everyone can view them but give it a try. If it does not work I will figure out another way to share them.

https://drive.google.com/drive/folders/0B6eDAxemj1VHZjk2NTgwNWItMGUzNy00YzhhLWI4NGQtNzc3MTU4OGE5MjRh
Harry Smith
ATCA 4434
TCI

"There is no try,
there is only
do or do not"

Offline RB

  • ***
  • Posts: 235
Re: 555 pbx cord set questions
« Reply #4 on: September 26, 2017, 02:56:08 PM »
Thank you Harry!!! I was able to locate and download a clean schematic.
it will help bunches. :)

Offline HarrySmith

  • Hero Member
  • *****
  • Posts: 4304
  • 1956 Rose Beige 500
Re: 555 pbx cord set questions
« Reply #5 on: September 26, 2017, 05:22:14 PM »
YW! Glad it helped!

Also for anyone else with a 555 board that link contains just about everything printed on the board.
Harry Smith
ATCA 4434
TCI

"There is no try,
there is only
do or do not"

unbeldi

  • Guest
Re: 555 pbx cord set questions
« Reply #6 on: September 27, 2017, 09:53:06 AM »
I cant read the schematics clear either. Usually a retardation coil is used to keep DC current out of some part of the circuit.

Retardation coils do not keep DC current out of anything.    For DC current they only present the ohmic resistance of the wire used to make the coil. This resistance is typically kept small to prevent dissipation in the coil.  They are used to block voice currents,  for example to prevent shorting voice currents while it is desirable to maintain a DC supply voltage for signaling.  Voice currents are similar to alternating currents, but vary in frequency from a couple hundred to ca. 3500 Hz in the typical telephony base band. The retardation coil presents a high impedance due to self-induction to alternating currents, therefore it prevents shorting a source of voice currents, for example, while maintaining the flow of DC.

The retard coil is therefore the opposite to the capacitor, which indeed blocks  direct current, but only presents a certain impedance to alternating current.
« Last Edit: September 27, 2017, 09:57:39 AM by unbeldi »

Offline RB

  • ***
  • Posts: 235
Re: 555 pbx cord set questions
« Reply #7 on: September 27, 2017, 11:50:20 AM »
Thank you for your wisdom, Unbeldi !
As always, you turn the lights on when you enter the room :D