12-19-2017, 11:02 AM
It's still overcast, and this hole actively repels light. I put a 25W LED lamp directly on the subject, and this is the best photo I could get.
https://imgur.com/a/FbUEt
Top of photo, left to right: LED display for the digit receiver; line finder and digit receiver on one card; 8x8 crosspoint switch; 4 SLICs on one card; ringer; call progress tone generator.
Bottom: 60 watt powered USB hub, C.H.I.P. single-board computer.
I think we've discussed everything except the line finder and digit receiver.
The line find simply polls the switch hooks of the SLICs in an endless loop to determine which lines are off the hook.
The digit receiver counts the pulses from a rotary dial and translates them into the digits of a telephone number. The phones in this system will have 4-digit numbers. I obviously could've given them one-digit numbers in a system this small, but dialing the number is part of the fun, right?
Rotary dialing works by disconnecting the phone line very rapidly. For instance, if you dial a 5, the line is disconnected and reconnected 5 times. You could actually dial a number by jiggling the switch hook if your timing was precise enough. Most people's timing wasn't that precise, which is why they invented the rotary dial.
https://imgur.com/a/FbUEt
Top of photo, left to right: LED display for the digit receiver; line finder and digit receiver on one card; 8x8 crosspoint switch; 4 SLICs on one card; ringer; call progress tone generator.
Bottom: 60 watt powered USB hub, C.H.I.P. single-board computer.
I think we've discussed everything except the line finder and digit receiver.
The line find simply polls the switch hooks of the SLICs in an endless loop to determine which lines are off the hook.
The digit receiver counts the pulses from a rotary dial and translates them into the digits of a telephone number. The phones in this system will have 4-digit numbers. I obviously could've given them one-digit numbers in a system this small, but dialing the number is part of the fun, right?
Rotary dialing works by disconnecting the phone line very rapidly. For instance, if you dial a 5, the line is disconnected and reconnected 5 times. You could actually dial a number by jiggling the switch hook if your timing was precise enough. Most people's timing wasn't that precise, which is why they invented the rotary dial.
