Nevermind, turns out I am just such a noob that I misunderstood how the breadboard is laid out. The circuit works great.
**broken link removed**
**broken link removed**
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hi everyone, I have a question about setting the reference OUT of the LM3914. I am using a 5V power for my project and I would like to set the Ref Vout to detect 3.0V at peak level. I used the equation Ref Out V = 1.25(1+ R2/R1), R2=5.1K, R1=3.6K. I expect to see a 3.02V in pin 6&7, however when I measure it, I got 3.32V. Does anyone can help me with this issue??
On page 8 of the LM3914 Datasheet, I saw another equation Vout = Vref*(1+R2/R1) + Iadj*R2. How can I calculate Iadj??? which formula should I use?? the first one or the second one???
Thanks ericgibbs, the calculated RefOut value by your calculator is exactly what I expected to see, but in real life, I got 3.32V on the RefOut (pin 7), do you have any idea why?
I just checked the current Iadj with a meter, the reading is around 60uA,
Vout = Vref * (1+R2/R1) + Iadj*R2 = 3.02 + (60uA * 5.1K) = 3.32V which matches the measured Vout value, However, does anyone know how to calculate Iadj??
The pic you just show. Is it part of another program or is it a software program on itself. If it is, please give me the linkhi goaticus,
Give me a minute just got my wires crossed at this end...
I will repost.
EDIT:
Here we go.
Look at this image, set up the LM3914 this way.
To Calibrate the sensor amp I would use a 100R variable resistor to simulate the tank sensor.
At first set both the Zero and Span pots to 50% rotation.
1. Set the sensor sim resistor to 77R and adjust the Zero so that LED#1 lights.
2. Set the sensor sim resistor to 7R and adjust the Span so that LED#10 lights
repeat this from line number 1 until the LED's are LED#1 for 77R and LED#10 for 7R
OK.