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

[Rick Martin]

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?

 

[rolerbe]

Look at: http://en.wikipedia.org/wiki/Transimpedance_amplifier to convert current to voltage, fed as input to an LM3914 IC to an LED Bargraph (radioshack) or discrete LED's

 

[Bob S]

National Semiconductor makes the LM3915 ten-LED display driver chip for VU meters. Several manufacturers make kits using this chip.
See http://www.arcade-electronics.com/detail.aspx?ID=17694

 

[rolerbe]

Yes, Bob. The LM3914 is the linear version of the LM3915. All depends on if you want linear or log response.

 

[Rick Martin]

Thanks, guys! Looks eminently reasonable. Sure appreciate the info.