[sdiy] MIDI activity LED circuitry

[Scott Gravenhorst]

Hallvard Tangeraas <my_list_address at yahoo.no> wrote:
>On 24/2/07 13:33, Rainer Buchty wrote:
>>> If such a circuit is dependant on the MIDI ports' own circuitry I can 
>>> try to provide more information about that, but perhaps it's just a 
>>> matter of adding some new circuitry to the existing inputs and outputs?
>>
>> For the output ports I'd go right before the output driver (typically 
>> single transistor or 7406) and add another driver for the LED; 
>> input-wise similarly after the opto coupler. 
>So I can simply "tap" the needed signals from the 7406 or transistor 
>which should be present at every MIDI output or input; there's no need 
>to modify them?
>
>Do you have any schematics for this? I'm not very good at electronics 
>theory and design, but rather the practical side of it all.

Just a thought here, I'm designing an FPGA MIDI synth, I decided to display MIDI
activity in one of the LEDs on the dev board and while the LED is actually quite bright
when simply turned on, it is very dim when used as a MIDI monitor.  It may be better to
trigger a one-shot with the MIDI data signal and drive the LED with the output of the
one-shot.


-- ScottG

---------------------------------------------------------
-- Scott Gravenhorst
-- Xilinx Spartan-3E Based Music Synthesizers
-- FatMan: home1.gte.net/res0658s/fatman/
-- NonFatMan: home1.gte.net/res0658s/electronics/