LED Question

ajward · 2013-05-22 17:17

Hi All...

I'm experimenting with a 10 segment bar graph display. At first, I plan for no more than one bar to displayed at a time. Can I get away with connecting a current limiting resistor to just the cathode for now? Understanding that I might have to put resistors on each of the anode leads later on.

Thanks for any wisdom!

Amanda

Heater. · 2013-05-22 17:46

Sound OK to me.
What could happen? If that resistor value is right for driving a single bar at reasonable brightness then if you accidentally turn on two or more bars those LEDs will get half or less of the current they like each and glow dimmer. No harm done.

ajward · 2013-05-23 00:24

Thanks Heater! That's what I thought. I just wanted to be sure. On a limited budget here and I don't want to fry things needlessly.

Amanda

edit: Though the display was discontinued and not listed in the local Radio Shack inventory, and the manager gave it to me for free! Yay 'Shack!

LoopyByteloose · 2013-05-23 11:01

I have always found it frustration that those LED bars come in 5 or 10 LEDs, not 4 or 8.

Everything about mircocontrollers in binary, except these LED displays. Very mysterious. I guess the human interface just needs to pretend that decimal numbers are in control.

RDL2004 · 2013-05-23 11:06

Yeah, and you can get arrays of 8 resistors in DIP packages which are perfect for use with 7 segment displays, but packages with 10 resistors are almost impossible to find.

Heater. · 2013-05-23 11:10

I'm still looking for a bar graph display that goes to 11.

Whit · 2013-05-23 12:01

@Heater - I think you dated yourself on that comment...Most only go to ten.

LoopyByteloose · 2013-05-23 12:06

Heater is dating himself. What will his girl friend think? Or his spouse?

I do have a pile of rectangular LEDs with which you can build your own bar graph of any number. But be forwarned, it take practice and patience to get them to align perfectly when soldering.

Martin_H · 2013-05-23 12:14

Whit wrote: »

@Heater - I think you dated yourself on that comment...Most only go to ten.

Up to eleven is now a key part of western culture:

http://en.wikipedia.org/wiki/Up_to_eleven
http://tvtropes.org/pmwiki/pmwiki.php/Main/UpToEleven

So I sugest wiring eleven LED's by hand. After all, if someone's LED bar graph is at ten it's maxed out. But with eleven LED's you can go one brighter then them.

pmrobert · 2013-05-23 12:15

Loopy Byteloose wrote: »

I have always found it frustration that those LED bars come in 5 or 10 LEDs, not 4 or 8.

Everything about mircocontrollers in binary, except these LED displays. Very mysterious. I guess the human interface just needs to pretend that decimal numbers are in control.

They're in the food business too.....

RDL2004 · 2013-05-23 12:39

attachment.php?attachmentid=101784&d=1369337846

Homemade LED bargraph. Uses a header socket and 2mm LEDs. The LEDs can be quickly rearranged, changed out for different colors, or they can be removed completely to allow access to the Propeller pins. Uses a DIP resistor array for current limiting (in the foreground between the reset button and voltage regulator).

mindrobots · 2013-05-23 12:41

Very nice!

...plus, you can go to 8, 10 ....or even 11!!

LoopyByteloose · 2013-05-23 13:42

BTW, while nobody make a 10x in line resistor package, you can use two 5x packages with 10 LED configuration.

I guess if you had 11 LEDs, you could use one 6x and one 5x end to end. There are solutions for those that think.

LED Question

Comments