Gents,

I looking at the LM3914 or a Quad Op Amp for the following result from a single analog line:
9V = turn on PNP FET or BJGT to short DC motor terminals

10V = turn on PNP FET or BJGT to short DC motor terminals, Turn off 2 of 4 in Series LED (came on at 5 volts),

12V = Funcs of 9V, 10V off, Turn on NCh Fet for DC motor

14V = Funcs of 9V, 10V off, Turn on NCh Fet for DC motor, Turn on 4 of 4 LEDs at lower current/brightness

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The steps can be modified if needed. I like the idea of using the "dot mode" in the LM3914 for built in auto turn off of functions, but am concerned whether I have control over the steps/range (get 1-2 volt per step?).

I can go with the OpAmp, but have to do all the turn off stuff manually which is doable.

I want low part count, simple analog function, which method do you guys recommend? Know of projects like this? I searched the forum, but did not see an answer.

Sincere thanks,

MTI

 

Use the LM3914 in dot mode and drive each device with transistors. Simple and easy.

 

You could well be right. Any idea where a SPICE model for it would be? National did not seem to anxious to create one. Or is it just too obvious?