The 5 Times Around circuit was designed to automatically let an N Scale locomotive and car travel around a loop 5 times and stop for approximately a minute and then repeat the cycle. The loop of track was set up as an amusement park type of ride in the trolley section of The London Model Railroad Group's, 'O' scale layout located at London, Ontario, Canada.
Each time the train covers the photocell mounted between the rails, the first LM556 timer section is triggered by the LM393 comparator. This timer is a negative recovery type to ensure that only one pulse is generated each time the train passes over the cell.
The 4017B divider IC counts the number of times it receives a pulse at its number 14 pin. On the 4th. pulse the number 3 pin goes high and when the 5th. pulse is received this pin will go low and cause the second LM556 timer to trigger.
The second timer controls the length of time that the train is stopped. When triggered its output is high, the relay is turned on and the track power circuit is opened. The length of time that the train is stopped can be changed by adjusting the values of the 470K resistor and the 68uF capacitor.
The train will stop at the location of the photocell, therefore it is placed where passengers would get on the ride.
If no power is connected to the control circuit the train will run all of the time.
The circuit can operate automatically or manually depending on the setting of S2.
The 4017B integrated circuit can be wired so that from 1 to 9 laps can be made between waiting periods. This is done by connecting any one of the divide by 1 through 9 outputs to the reset at pin number 15. Please refer to a manufacturers data sheet for more information on this device.
The control circuit is powered by a plug in type AC adapter with a filtered DC output that is large enough to operate the relay, 9 Volts at 200Ma. is OK. The N scale train is powered by an old power pack.
It should be noted that when power is applied to the circuit, the 4017B will not be at a zero count and the second timer will turn on. Therefore the first cycle will be shorter than those following and the train will not run immediately.
The next circuit is an addition to the 5 Times Around circuit as made by Jim Bloom (email@example.com).
The circuit allows the user to select, between 1 and 7, the number of times the train travels around the loop before it stops.
The explanations for the circuits on these pages cannot hope to cover every situation on every layout. For this reason be prepared to do some experimenting to get the results you want. This is especially true of circuits such as the "Across Track Infrared Detection" circuits and any other circuit that relies on other than direct electronic inputs, such as switches.
If you use any of these circuit ideas, ask your parts supplier for a copy of the manufacturers data sheets for any components that you have not used before. These sheets contain a wealth of data and circuit design information that no electronic or print article could approach and will save time and perhaps damage to the components themselves. These data sheets can often be found on the web site of the device manufacturers.
Although the circuits are functional the pages are not meant to be full descriptions of each circuit but rather as guides for adapting them for use by others. If you have any questions or comments please send them to the email address on the Circuit Index page.
23 January, 2017