This page presents a new version of the - 'Modernized "Toy" Throttle' circuit that is shown on the 'Various Transistor Throttles' page at this site.
This version was specifically design to be used by a handicapped person and is controlled by a single axis joy stick that operates microswitches at each end of its arc of travel.
There are two modes of operation with this design.
In the first mode (S4 - Open, S3B and S6B - Positions 2 to 5) the train will run for a preset period of time and then gradually slow to a stop unless the timer is re-triggered. As long as the operator re-triggers the timer the train will run continuously. The timer can be re-triggered at any time and five run periods can be selected.
In the second mode (S4 - Closed, S3B and S6B - Position 1) the train will run for as long as a direction switch is held closed. If no switches are close for approximately two seconds the train will slow to a stop. Closing a switch will continue the run.
The throttle has automatic current limiting set at 0.8 amps and can be equipped with direction indicating LED's if desired.
Due to the nature of the throttles design. - If the direction input is suddenly changed the train will slow to a stop and then accelerate in the opposite direction. This eliminates sudden, violent changes in direction and may be less confusing to the operator.
The function of the various controls are marked on the schematic diagram as well as some of the operation notes.
The circuit uses an LM556 dual timer in a cross canceling configuration to provide the time functions. For more information on this, refer to the Cross Canceling For Monostable Timers section of the LM555 and 556 Timer Circuits page at this site.
A 6 position - 2 pole rotary switch was used to set the running times as this was less expensive and easier to find than a dual potentiometer
Current limiting is set by resistor R22. this could be changed to suit your needs as long as adequate cooling is provided for the output transistors Q1 and Q3.
The optoisolators used in the circuit provide separation between the sections of the circuit that use a single sided power supply and those that use a dual power supply.
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.