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555 schematic?

Started by RB, May 02, 2017, 12:41:10 PM

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is there a complete schematic available for a 555 cord board?


Well, "complete" depends on what the installed features are and their dates.
For the basic standard board, the circuit drawings and circuit descriptions are available, yes, I am not sure about every circuit.

Here are some on my disk, that I could quickly find, but I am sure there are more somewhere.

Bell System Practices (BSP) Section 536-550-110 i1 520422 General Description; 555 PBX

GTE/General System Practices (GSP) Section 503-620-400 i1 6512 Description, Circuits; 555 PBX Switchboard

WECo CD 65715-01 Central Office Trunk Circuit
WECo SD 65715-01 Central Office Trunk Circuit


Thank you.
is there a way I can view them?

Victor Laszlo

Does your board have the circuit labels glued to the inside of the rear cover?


oh, the OP is our switchboard constructor.  He probably doesn't have a 555 himself.

Here are the practices I mentioned, they contain general information applicable to the generic 555 design.

Quote from: Victor Laszlo on May 02, 2017, 03:09:34 PM
Does your board have the circuit labels glued to the inside of the rear cover?



I have a ton of 555 switchboard stuff saved on Google. I am not sure if you have to be signed in to see it but here is the link:
Harry Smith
ATCA 4434

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


Thank you unbeldi and Harry! lots of good stuff there.
The board is coming along well. Hope to give it the first spark test this weekend!