P13361: System Dynamics Filtering Laboratory

Lessons Learned

Table of Contents

The following documents the lessons learned during the design process and suggestions for further improvements

Printed Circuit Board

Suggestions for Improvement

Revisions were made to the PCB for future development including:

- Extra spacing towards the edges of the board for easier mounting
- Relocation of speaker connection points for easier access to the voice recorder board
- Modification of test point mount holes (change from 2 holes to 1)

Other suggestions to improve the borad:

- Alter the signal selection portion (JP1 & JP2) such that a rotary switch mounted on the interface panel would be used instead
- The built-in filters on the board may be altered to change their cut-off frequencies to make the filtering effect more apparent

These changes yield a more refined layout and easier product assembly

Lessons Learned

- Originally, LM741 ICs were intended to be used for the prefab filters on the board. This idea was eventually dropped in order to make the filters more representative of a circuit diagram of a filter
- The test points on the prototype board are attached through two holes, but it was discovered that only one mounting hole was needed. This change is represented in further revisions of the board layout

Hardware Activity Kit

Suggestions for Improvement

Possible improvements to the hardware kit's design include:

- Addition of a physical barrier around the hardware module in order to prevent loose components (i.e. resistors, ICs, etc.) from falling into the product
- Use of silk screening to label the interface panel
- Use of opaque acrylic for the interface panel to make the connection labels easier to read (this would be especially useful if silk screening is used for the labels

Lessons Learned

Lessons learned while designing the hardware kit inclued:

- Additional material needed to be added around the enclosure mounting holes to ensure structural integrity
- Plexiglas/acrylic used for the mounting plate and interface panel must be at least 1/8" thick to ensure structual integrity

Enclosure Issue

The production product enclosure is a non-stock item, meaning it has a 13 week lead time for delivery. This caused the prototype to be delivered without a box. Therefore, if this product is to be mass produced, the lead time for the enclosure must be accounted for

Software Activity

Suggestions for Improvement

Final code improvements include:

- The addition of a skeleton filter that can be used to implement new image filters
- Since the output from the hardware kit can be sent to a DAQ, the software can be expanded to process the audio output, allowing the filtered or unfiltered waveform data to be visualized or manipulated on the PC workstation

Further Reading

For further information on the subject, see section XII of the technical paper here

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