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The Inside Story

First, a prototype was built for proof-of-concept. It is a working model but makeshift in construction. It has full functionality but with point-to-point wiring on the under side. So, it is messy to work with and repair. The 5 relay buttons are offset to accommodate two hands operating the buttons. There is an external power supply box with 5V (Arduino), 36V (relays) and power for a Bose speaker. Including the 3 power supplies within made it too bulky. 

Prototype for interactive tribute to telephone relays demo device

For the final model, a custom-made front panel was constructed with engraved labels and mounting holes for the 5 relays. Also, a bespoke PCB motherboard was made with mountings for an Arduino Mega 2560, a MP3 player and a Real Time Clock with battery backup. In clock mode, pressing the Take button plays the current time using a voice similar to those used in the Bell System for their vintage ToD service. The relays once serviced subscribers in Panel and Crossbar exchanges in San Francisco, Ca.  

Inside the interactive demo device for telephone relays

The video below is a short walking tour of the inside.

5 telephone relays part of interactive demo system

Following are various relays in exchange service. 

E relays from a Panel Telephone Exchange, San Francisco 1930's

E relays in rack -- from a Panel System, circa early 1930's, San Francisco, Ca

Extreme close-up, 2 R relays in rack -- from a Panel System, circa early 1930's, San Francisco, Ca

Extreme close-up, two R relays in a rack -- from a Panel System, circa early 1930's, San Francisco, Ca

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