Child Friendly Timer

Designers: Mike McCarthy and Justin Wool
Client Coordinators: Lenore Champion , Duke University Medical Center
Supervising Professor: Dr. Larry N. Bohs

The objective of this project is to build a timer that is visually and aurally enticing to brain injured children in the Duke University Medical Center. The child friendly timer shows the passage of a specified period of time and helps these children learn that they must complete tasks such as eating at specific times. The timer is aesthetically consistent with the toys that young children have, and compact enough so that the workers in the rehabilitation center can carry it with them to their desired location. The timer countdown time can be set in increments of one minute up to a maximum of thirty minutes. At the end of the countdown, the timer provides a distinct climatic event of lights and sound that signals time has expired.

The child friendly timer device is used in the Duke Medical Center as a child rehabilitation aid. It shows the passage of time visually, helping disabled children to learn the significance of time duration in everyday activities.

How this project helped
Children with brain injuries are often unable to focus on a specific task, which can make them unable to perform essential human activities, such as eating. The child friendly timer teaches children how to focus on eating for the proper length of time. It also shows them the importance of the passage of time while they are completing other important tasks. The climbing fireman is interesting to children, but not so   interesting that it detracts them from the task at hand. The timer is large enough that they can visualize the passage of time periods of several minutes.

The child friendly timer is developed from a commercial toy in which a fireman climbs a 4-ft. ladder. fireman climbs up a ladder as the timer counts down from the initial starting point. As the clock runs out, the climber reaches the top of the ladder, and then returns to the base of the toy. When the fireman reaches the top, a music and light show clearly signal a conclusion to the amount of time the child will have to finish the activity. The timer is controlled by an electronic system including a BASIC stamp microprocessor and several other components (see Figure 2).

Five interface buttons provide the inputs to the timer. The user resets the timer value with one of the buttons and increments the time of the clock with another button. A third button signals the timer to start counting down. The fourth button stops or pauses the timer while it is counting down and the fifth button triggers an emergency finale while resetting the timer count to zero. An LCD display, which is mounted to the surface of the device, shows the time remaining in the countdown process once the timer has been started.

The microprocessor controls the operation of the child friendly timer. Initially, the user sets the clock to the desired duration for the therapy session. Based on this time, the microprocessor calculates the number and duration of steps that the fireman will use in climbing the ladder, so that the top is reached just as time runs out. At each step, the microprocessor controls a reed relay switch that connects power to the motor inside the fireman climber for a specific duration.. Once the climber reaches the top, the microprocessor switches another reed relay to trigger a melodic generator circuit that plays “Old MacDonald.” The melodic generator circuit is connected to a speaker and audio amplifier housed within the toy case. A third relay is actuated at the end of the therapy session to control a light show consisting of forty LEDs, of which 20 flash in a random sequence. The climber is powered by two AA batteries, while the microprocessor and associated circuitry uses four C batteries. The final cost of the project was about $400.

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