Designing an LED Array Circuit for Real-Time Feedback on Exercise Equipment

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Discussion Overview

The discussion centers on designing a circuit for an LED array that provides real-time feedback on exercise equipment. The focus is on how to effectively integrate the LED array with the existing power supply and current monitoring system, exploring various components and configurations suitable for this application.

Discussion Character

  • Technical explanation, Exploratory, Conceptual clarification

Main Points Raised

  • One participant describes a modified exercise equipment setup that generates 12v DC and monitors current, seeking advice on integrating an LED array for feedback.
  • Another participant suggests using a transimpedance amplifier to convert current to voltage, which could then be input to an LM3914 IC to drive an LED bargraph or discrete LEDs.
  • A different participant mentions the LM3915 chip, which is designed for ten-LED displays, and points to available kits that utilize this component.
  • There is clarification on the difference between the LM3914 and LM3915, noting that the choice depends on whether a linear or logarithmic response is desired.
  • A participant expresses gratitude for the suggestions and finds the information helpful.

Areas of Agreement / Disagreement

Participants generally agree on the potential use of the LM3914 and LM3915 chips for the LED array design, but there is no consensus on the specific implementation details or preferences for linear versus logarithmic response.

Contextual Notes

Participants have not fully explored the limitations of their proposed solutions, such as the specific requirements for current handling or the integration with the existing monitoring system.

Who May Find This Useful

Individuals interested in electronics design, particularly in creating feedback systems for exercise equipment, may find this discussion relevant.

Rick Martin
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I've modified a piece of exercise equipment so that it generates 12v dc. Max current is almost certainly less than 1 amp (more than that, and the subject (exerciser) poops out fast). Standard (car lighter) plug allows any appropriate device to be powered. Current generation is being correctly monitored and reported graphically. All that seems to work just fine.

What I'd like to add is an array of LEDs on the equipment itself, to provide real-time feedback/encouragement to the exerciser/subject. Something like 150 ma lights one, 300 ma lights two, 450 ma lights three, etc.

Got absolutely no idea how to design that circuit. Any thoughts?
 
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Yes, Bob. The LM3914 is the linear version of the LM3915. All depends on if you want linear or log response.
 
Thanks, guys! Looks eminently reasonable. Sure appreciate the info.
 

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