Railroad Sound System  and Dual Truss Bridge additions
12/20/05  -- Trimble
Sound quality is fantastic!!!

Sound system uses 900Mhz cordless phones on different channels for sounds to different trains.  Inputs to the home base of each phone can come from a computer playing wave files or from a train sound system controlled explicitly.  The lower right
 pic is of the first creation using 2 cars and a larger phone on  two 40' flat cars and the second is all inside one 50' box car. 

A small 1 watt amp using a 9 volt battery is used to amplify the output of the handset. I removed the usual ear speaker and disconnected its microphone.

On the base unit I removed the level limiting transistor, and jumpered the normal line inputs directly to the sound interface with the transceiver board using 4.7uf tantalum capacitors.  Of the 12 wire interface (main handset board to transceiver board) one can simply take turns connecting to each wire until the sound is heard in the ear piece.

One could remove the outer casing of the handset to decrease the space required but the ease of recharging the handset batteries by setting it on its cradle would be lost, although, the improvising of a simple plug-in arrangement as it resides on the
car would not be a difficult either.  Alternatives are still being bounced around.

Click on pics to enlarge:

185' Dual Truss Bridge Addition    
A new Atlas dual track truss bridge with an added panel relative to the original kit was added to the O-scale layout to bridge the span at the entrance from the garage..  To accomplish this one panel extension, a single track Atlas truss bridge was cannibalized for parts.  A new wood set of ties replaces the plastic ones in the kit and the stainless steel bars buried in the longitudinal girders were lengthened by welding extensions onto them.  It is installed in a breakaway fashion in case it is bumped since all visitors will have to pass under it..  That is, it is free to move laterally or vertically with only the resistance of its mass.  The lateral position of the rails is maintained with brass channels less than 1/32" depth.

Final Bridge
Click on images for larger views:

Original Atlas Bridge from Kit:
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Detail Views Near end of construction:
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The  stainless bars were pinned to provide compression on the lower portion of the structure
and the computer milled plates were  added to enhance the contribution of the plastic trusses
for stiffening the bridge beyond what the steel bars provide.  In the original Atlas assembly
the trusses contributed virtually none of the bridge vertical support.  Bridge deflection even
with it full of locomotives is imperceptible.