After years of operating the same public display (Visitor push button = two trains run and stop at predetermined spot) we decided that an update was required for two reasons. The largely mechanical relay system we were using was 15 years old and no parts were available should we need them and second, the layout was much larger and two trains were often lost in the building.

We needed three trains running and we needed a reliable, fixable system.

In the spring of 2013 we decided on a system developed in California and widely advertised as capable of doing just what we needed. It was based on photocells and AND gate logic. Photocells would stop trains at desired locations on isolated track sections. When three trains were stopped at their respected locations the public push button would once again be enabled and the three trains would move one location down the main line to the next stop.

It did not work. Very long and noisy control lines, stray and changing natural light conditions and timing issues used up a full year of effort with no good results.

No disrespect for the manufacture. It worked every time in a test condition on or under the bench work but not in real live action.

In the end we opted for a simple Digitrax function by controlling the DCC/DC applied to three sections of track and programming every engine to NOT run on DC. When DCC was applied to the isolated tracks for 15 seconds trains would move out and then DC was reapplied to stop the next train in. No photo cells – no worries.

Asymmetrical DCC would have been a better solution but costly due to the need to replace nearly all our decoders.