[SOLVED] Valve Position Indicator

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msenkpiel

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I would like to use a potentiometer attached to a ball valve and e.g. (10) 2.5mm x 7.4mm rectangular LEDs to indicate the position of the valve: no LEDs lit = fully close, and 10 lit = fully open. This seems pretty simple and I can almost imagine this circuit, but wonder if someone out there could save me some trial and error. Thx!
 

If you can still find them, the LM3914 IC would be ideal for this. It is an LED bar graph driver, you supply it a voltage from the potentiometer and it lights the appropriate number of LEDs in sequence. Alternatively and maybe cheaper, you can use a small microcontroller with an ADC input to emulate the LM3914 but it would require some simple programming to make it work.

Brian.
 

The 3914 IC is a natural choice. If you cannot obtain one, then a substitute is a stack of 10 op amps, as window comparators. You'll also need 10 resistors, stacked to provide 10 voltage references.
 

Any micrcontroller with a built in ADC, 10 resistors, 10 LEDs. If powerrating is higher for LEDs then you can use LED driver. or simply sink the current into the microcontroller.
Comparator bank will also do it.
 

Thanks guys, the 3914 together with a 10 segment bar graph - red for hot water, blue for cold, worked perfect!
 

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