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About the Model Railroad

RTAC Software


The Randall Museum in San Francisco hosts a large HO-scale model model railroad. Created by the Golden Gate Model Railroad Club starting in 1961, the layout was donated to the Museum in 2015. Since then I have started automatizing trains running on the layout. I am also the model railroad maintainer. This blog describes various updates on the Randall project and I maintain a separate blog for all my electronics not directly related to Randall.

2018-01-05 - Activation Buttons

Category Randall

Issue: short push on activation buttons are not detected fast enough by the AIU01 polling.

Solution: use a basic RC to make the signal seem longer.

Experiment at home:

  • Use a 1000 µF between GND and the input.
  • Use a 110 Ω R in serie from input to button (to avoid shorting the capacitor).
  • This results in a hold time of about 5-7 seconds when fully charged.
  • When powering up, this also activates the input while the capacitor charges.

Quick drawing:

 Generated on 2021-01-20 by Rig4j 0.1-Exp-91c1dac