JMan

Bargraph/LED question
« on: October 26, 2020, 01:25:08 PM »
Hey everyone,

I am building a project that uses a run-of-the-mill 10-position LED bar graph for metering.  The build is an established project (the SB4000 compressor), and it is designed to work correctly with the bar graph.

I've looked at the data sheet for the bar graph, and it seems to just be 10 LEDs combined in a single component -- no other interconnections, no built-in resistors, or anything else inside.  So, is there any reason that I could not simply replace this with 10 discrete LEDs of the same rating, given that the circuit ostensibly already has all of the necessary components to drive the meter?  (I'm designing a custom front panel, so it doesn't need to fit into the same space as the bar graph).

In other words, is it as simple as: 1 10-position bar graph = 10 individual LEDs?

Thanks in advance!


mjrippe

Re: Bargraph/LED question
« Reply #1 on: October 26, 2020, 02:04:31 PM »

In other words, is it as simple as: 1 10-position bar graph = 10 individual LEDs?


In this case, yes.  I am looking at a bargraph card I just pulled out of a piece of PA gear and it is clearly just 10 LEDs in a plastic frame.  One side of all LEDs is common and the other is driven by the display chip.

You will want to replace them with LEDs of a similar rating to prevent excess current draw.  Also, if you are using multiple colors (mine is tri-color) you may have to add resistors to some to make the brightness appear equal.

JMan

Re: Bargraph/LED question
« Reply #2 on: October 26, 2020, 02:22:03 PM »
In this case, yes.  I am looking at a bargraph card I just pulled out of a piece of PA gear and it is clearly just 10 LEDs in a plastic frame.  One side of all LEDs is common and the other is driven by the display chip.

You will want to replace them with LEDs of a similar rating to prevent excess current draw.  Also, if you are using multiple colors (mine is tri-color) you may have to add resistors to some to make the brightness appear equal.

Thanks!  That’s very helpful!

JohnRoberts

Re: Bargraph/LED question
« Reply #3 on: October 26, 2020, 03:16:43 PM »
Yes, that simple... generally the LEDs pre-mounted into arrays are expected to be relatively close for brightness, but modern LEDs are more efficient than what the 39xx series LED drivers were designed for.

JR
It's nice to be nice....

JMan

Re: Bargraph/LED question
« Reply #4 on: October 26, 2020, 05:16:56 PM »
Yes, that simple... generally the LEDs pre-mounted into arrays are expected to be relatively close for brightness, but modern LEDs are more efficient than what the 39xx series LED drivers were designed for.

JR

Thanks, John!  I'm going to try it out and see if there's any need to adjust brightness with added resistors, but it sounds like this will be pretty simple overall.


 

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