pressed. This button would be used at Children’s Hospital and
on similar viewer-operated layouts.
Track wiring
In a loop layout, the stop block should be two or three times
the length of the locomotive. It is connected to the block
power contacts as shown and the track power is connected to
both rails of the track.
Prototype recorder
I mounted the controls for the recorder on a piece of Plexiglas
[7]. The Speed pot is in the lower-right, the Record/Play switch
is above it, and the Stop Block and Start buttons are to the left.
The heat sink extends through the project box. The track and
block connections are to its right, and the power plug and on/
off switch are to its left.
Important note on recording
Be sure to run your train or trolley until it warms-up (two min-
utes is plenty) before recording, as a cold motor with cold
lubrication runs quite a bit slower than when warm. This gives
you a much better chance of having a repeatable run.
Kit available from the author
A kit with all the parts shown in the article is available from
the author
All you need is a power
supply and a motor to control. The cost of the kit is $67 +
shipping. I can also supply a wired and tested unit, but my
hope is that most readers will enjoy the experience of build-
ing the kit themselves.
Going further
The Record/Playback program takes up less than half the
program memory on the PICAXE, so there is lots of room for
experimentation. With some software modifications, the unit
could easily be converted so that it not only records train
movements, but also throws switches and triggers sounds
based on train activity. The only limit is your programming skill
and imagination!
Video
This video shows the controller recording a trolley’s run on a
small layout, then replaying it. The test track and trolley are N
scale, but the controller will work with any DC-powered train,
including HO and G scale. As you can see, this is an ideal sys-
tem for demonstration railroads. We recently set it up at the
Carnegie Science Center during a weekend of train-related sci-
ence demonstrations, and let the young visitors record and
playback a session. They really enjoyed it, and I am happy to
report that it worked perfectly for two full days of operation.
PICAXE circuit part 2 - 7
MRH-Jul 2014
