Building Temperature Meter using UNOR3 and LM35 sensor

Other Hardware Sensors
21

So, this is the tentative final circuit (Fig-1) with transistor drivers on the cc pins of the display devices. Now at design level: total source current (considering all segments are On) ~= 51 mA (5.0-2.0/470) * 8 (switching: On for 5 ms and Off for 10 ms, Fig-2).

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Figure-1:

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Figure-2:

22 
V<sub>IL</sub>
P=I<sup>2</sup> * R

VIL
P = I2 * R

23

and the micro (u) symbol.

24

Another approach to consider is simply to increase the resistor values enough so that no transistors are needed.

Assuming the forward voltage of the segments is 1.8V, the resistors would need to drop 3.2V.

The absolute max current per pin is 40mA but I like to stay below 80% of that to ensure long life of the chip, so around 32mA. Shared between 8 segments this is 4mA per segment. So the resistors would be 3.2/4 = 0.8K. 820R would be the nearest (higher) common value.

So the question then is, will the display be bright enough? If not, you will need those transistors.

25

Let us see how the brightness appears in practice with "820R/1k segment resistor only" and "470R segment resistor + transistor".

26

In Windows you can use ALT codes. <ALT>0181 will give µ.

27

Nope doesn't work in Word or Notepad++.
In word < ALT > 0 and it wants to turn autosave.

You have to have a numeric keypad for to work, well you did in the olden days.

Tom.... :smiley: :+1: :coffee: :australia:

28

I did forget to mention that, thanks.

That's a different animal; I've tried it several times for different special characters and it indeed does not work. I also tried the suggestion in https://community.notepad-plus-plus.org/topic/13906/how-to-enter-greek-characters and did not manage; I did not look at the registry.
I don't use Word.
It does work in Firefox though.

29

option + m on the Mac.

µ

30

I use IBM Laptop and WIN10 and no numeric Keypad!

31

Then hammer + chisel.

32

What happens when you copy and paste the µ from this post into a text document?

33

It will apper as a picture like this:
image

The micro symbol is in the symbol list of MSWord from which I can copy and paste it. I have wanted to use it in the Arduino forum post.

34

Copied fine into Word and Notepad++

Tom.... :smiley: :+1: :coffee: :australia:

35

How about into a forum post?

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µ

Tom.... :smiley: :+1: :coffee: :australia:

37

How does it appear?

38

If I need a special character on the forum, I cut and paste it from Excel.

Whatever spreadsheet I have open, I 'Insert' a 'Character' into an empty cell, and then use Ctrl c and Ctrl v to copy and paste from that cell.

39

Windows also has charmap.exe; it's a bit of a nightmare to use.

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40

Check if you don't have a key to switch.

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I think that on this one it's the NUM key.
I hope it's visible that e.g. J, K and L are 2, 2 and 3.