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Seeking help on circuit design for LED rudder indicator

Sunnysky

Jul 15, 2016
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what is the purpose overall? mini-scale sailboat, real size, better feedback, resolution? remote control?
 

Alec_t

Jul 7, 2015
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mult both R suggestions x10
No. Don't forget that in bar mode all 10 LEDs may be on simultaneously and all can draw their current via a shared single resistor. See the LM3914 datasheet.
 

Alec_t

Jul 7, 2015
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Here's a sim of the 'jiggle the references' approach in post #17.
RudderIndicator(non-linear).JPG
The 'In' voltage is derived from the rudder pot and unconventionally is applied to pin 6 instead of pin 5. Pin 5 gets a fixed 'half the supply' voltage instead. This approach results in non-linear intervals between the voltages at which successive LEDs turn on, but that could be an advantage in that there would be greater sensitivity to rudder position changes near the central position. What do you think, Weegiemann?
 

Sunnysky

Jul 15, 2016
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No. Don't forget that in bar mode all 10 LEDs may be on simultaneously and all can draw their current via a shared single resistor. See the LM3914 datasheet.
I was thinking of dot mode with pin9 open.
ty
 

Alec_t

Jul 7, 2015
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Here's a sim of the opamp approach mentioned in post #17. I haven't shown all the LEDs. This option gives a linear spacing of the LED trip points.
U1d inverts the rudder pot signal going to the port-side LM3914. The other opamps in the quad package (LM324) are unity gain buffers for the rudder pot signal and reference signals. Depending on which opamps are used, they may need a supply voltage >5V.
RudderIndictor3.JPG
 

Alec_t

Jul 7, 2015
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... and here's a sim of the 'add inverter stages for each port LED' approach in post #17. Again, I've only shown some of the LEDs :-
RudderIndictor4.JPG
 
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