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    help needed hooking up 4 lm3914

    Thanks Audioguru, I put it together like your drawing and it works great.  As far as the regulators, I was just trying to keep the thing as cool as possible.  It's going into a space without much air movement.  I'll be putting a heat sink on it when it's done. Now I just have to put it into a...
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    help needed hooking up 4 lm3914

    Ok, I tried using an LM324 as a pulse width modulator to control the voltage to the led's through a transistor.  This does work however as more led's light in bar mode the brightness changes.  Is this not a good way to control the brightness?  Why is the brightness going down as more led's light...
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    help needed hooking up 4 lm3914

    Thanks MP, Last nigt I found that if I put a 2K resistor and a 100K pot between pin 7 and ground I got brightness control with a full sweep of the pot.  The circuit is turning out to be a lot simpler than I thought it would be.  No op amp needed and whatnot. I still have the question about...
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    help needed hooking up 4 lm3914

    I think I got the pots setup correctly.  I found I needed to put one side to + and the other to - with the wiper going to the signal in of the chips. Theres still the question of brightness control.  Can it be done with one adjustment? Thanks, davidk
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    help needed hooking up 4 lm3914

    I've been looking at resistor networks and it seems any thing over 2 or 3 resistors and it gets verrrry hard to calculate.  So how bout having separate pots for each voltage needed?  I modified my drawing showing 5 pots to set the hi and lo voltages for each chip. Will the separate pots idea...
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    help needed hooking up 4 lm3914

    I'm sorry, "dividing the output of the transducer" may have been an incorrect phrase.  I'm passing the output directly to each chip and trying to set the Rlo and Rhi to give me what I want. I re-read the datasheet aloud to my disinterested wife and realized I was skimming over some important...
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    help needed hooking up 4 lm3914

    Hi, I'm trying to use 4 lm3914 for a preasure gauge using an mpx4250a transducer. I'd like to have the first ten led's setup for dot mode from a voltage of .2 to 1.7. The remaining 30 led's would be setup for bar mode from a voltage of 1.7 to 3.2. I'd also like to be able to adjust the...
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