LED question

[tgp]

hey all. im trying to implement this schematic into my LED's on my midibox:

it uses to amps, one to bring the LED from 0v to its set voltage, then one to bring it from set to 0v. thus creating a pulse effect.

the parts are pretty cheap, but when i have 50 or so buttons i want to use this with then it gets a bit costly.

is there anyway i could use this schematic as a 'LED master' pulse section where all pass thru this before the LED.

only thing i can think of is it messing up by pressing another button while the one before it hasnt finished its pulse cycle yet.

let me know if you have any ideas!

thanks.

taylor

[jstoecker]

hey all. im trying to implement this schematic into my LED's on my midibox:

Where in this circuit are you intending to connect your "control" line from the DOUT or whatever?

As it is right now, I don't think you could make it work.  But with some changes, maybe: if you had an NPN configuration, where the transistor is "below" the LED/resistor pair (as opposed to the configuration  in the diagram"above") [so in other words, change the circuit to current sinking instead of sourcing], then you might get away with feeding each LED from the DOUT as per the example for 32 LEDs from a DOUT

http://www.ucapps.de/mbhp/mbhp_doutx4_32leds.pdf

and then instead of tying all the other end of each LED to ground, tie it to your flasher circuit..

(Or maybe the existing circuit would work OK as a current sink?)

Of course,  all the LEDs would pulse/flash at the same rate. If you had quite a few of them turned on, you might find you need a beefier transistor...

Just an idea,

John

[TK.]

You could implement this via software to save hardware costs...

Best Regards, Thorsten.

[tgp]

thx for the post TK.

could you go a little more indepth? at what level language would it have to be programmed? when you say software side do you mean MIOS or write a stand alone application to control sent voltage, ect?

good idea, will save me alot of $. thank you!

taylor

[TK.]

Hi Taylor,

normaly it can be programmed into the application, MIOS code doesn't need to be touched.

Which application are you using exactly?

Best Regards, Thorsten.

[tgp]

you mean which host application? this is going in an LC and controlling Logic 7 pro.

[TK.]

I've currently no clear picture of what you are trying to do, therefore I cannot give you a clear answer.

I asked for the MIOS application, because the implementation will heavily depend on the program which has to be modified. E.g., the MIDIbox64/64E is programmed in assembler, the MIDIbox LC (new version) in C.

On the other hand: in my oppinion it is not really useful to integrate flashing LEDs into a Logic Control emulation, because the host flashes the LEDs by itself if required. E.g., when you select the Solo button, the Mute LEDs of all not-soloed tracks will flash. An additional flash algorithm from MIDIbox internal would propably only confuse.

Best Regards, Thorsten.

[tgp]

TK,

thanks for the reply.

actually im not trying to flash a button as if i was in RecordArm or the likes, im trying to fade up to and fade down from a button push instead of having it just hit with luminosity all at once.

ex. think the Apple monitor/desktop on and off button. when you touch it it "glows" or fades in and out instead of just coming on and off.

any clearer/advice?

thanks!

taylor

[TK.]

Hi Taylor,

ok - now I understand what you mean with pulse effect. It's possible to dim the LEDs via pulse-width-modulation. It wouldn't cost much performance (and wouldn't consume too much memory) if only one or two LEDs are dimmed, but for 50 LEDs I see no chance to integrated this into the MBLC application - the CPU load is already very high, especially when the host application sends a lot of MIDI events at the same time. An additional PWM handler for so much LEDs would provoke MIDI buffer overruns.

Best Regards, Thorsten.

[tgp]

TK,

by "50 LED's" do you mean at the same time or the memory to program PWM for each of them?

i was hoping on using the pulse for all the buttons and the LED rings (not for the meters though)

i wouldnt be pressing more than one button at a time, but with the LED rings they are going to be going all at the same time if theres alot of panning.

is there no hardware way to do it (like the schematic at the top) and still comply to the hookup pattern for the midibox?

thanks.

taylor

[TK.]

(I've no solution)

Best Regards, Thorsten.