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General Discussions => Drawing Board => Topic started by: Mbira on May 05, 2009, 05:59:32 PM

Title: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigger
Post by: Mbira on May 05, 2009, 05:59:32 PM
Hi guys,

I'm using these:
(http://img3.musiciansfriend.com/dbase/pics/products/regular/3/9/3/256393.jpg)

Going through this to convert the pickup into midi and trigger samples through Ableton:
(http://www.bhphotovideo.com/images/images345x345/461469.jpg)

So I have these discs that I will hit as triggers, but I really would like to be sure when one is activated.  Can you suggest a way to do that? 

One way is maybe there is a midi to LED box and I could send the midi message from Ableton to light the same event that is triggered by the hit?

Any thoughts?
Title: Re: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigger
Post by: Curtis on May 05, 2009, 07:09:11 PM
Cheapest way I can think of is tapping off a signal from the trigger before it gets to the MIDI "brain".

Trigger -> Buffer -> Monostable de-bouncer/pulse stretch -> LED

Probably about 5 bucks worth of parts per trigger, although it won't help if you're trying to confirm the MIDI side of things.
Title: Re: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigger
Post by: clintrubber on May 05, 2009, 07:24:14 PM
One way is maybe there is a midi to LED box

I think the solution can be pretty simple if you don't need individ. LEDs for each pad.

Just split your generated MIDI-data into the original destination and a feed for the monitoring circuit.
Note a MIDI-input circuit is usually an opto-coupler, 'so the incoming part is a diode'. We now just use a diode that's visible outside:

To spot MIDI-activity I've a few simple DIN-5 plugs in the tool/gizmo-box that are just
the connector, a LED, a series resistor (220 Ohms ?) (and an anti-||-diode IIRC).

This can spot single MIDI-notes well, even short hits.

Only complication can be if the MIDI-box already generates a stream for some reason
that spoils the contrast to the drum-hits. If there's such 'background data' check if you can disable it.


Bye,

  Peter
Title: Re: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigger
Post by: Mbira on May 05, 2009, 07:47:36 PM
Hey-I do need individual LEDS for each.  To clarify, there will be 9 triggers that are each programmed to trigger a specific place on the timeline in Ableton.  IE: Only one will be used at once.  Not sure if that changes things.  The reason I need the light is to be sure:
1. the sample got triggered
2. So I can remember which one I just hit so I hit the next correct one in sequence.
Title: Re: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigger
Post by: clintrubber on May 05, 2009, 08:02:43 PM
For indiv. indication I'd now turn to some software application that you can run alongside Ableton, reflecting the status of incoming MIDI. Would that be OK or do you need some indication away from the screen ?
Title: Re: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigger
Post by: Mbira on May 05, 2009, 08:25:31 PM
Yes please. ;D Because we are jumping all around the stage and the idea is these things will all be set on the computer so we don't have to (can't) watch the screen.  I'm wondering though about sending a midi signal and triggering an LED?  Seems like that would be semi-common?
Title: Re: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigger
Post by: clintrubber on May 05, 2009, 08:47:59 PM
Yes please. ;D Because we are jumping all around the stage and the idea is these things will all be set on the computer so we don't have to (can't) watch the screen.  I'm wondering though about sending a midi signal and triggering an LED?  Seems like that would be semi-common?


You'll then need some decoding of the MIDI-notes into separate LEDs.

And you'll need some method to extend the LED-on after the trigger has ceased.
You'll probably want to have the LED on as long as the sample/loop/thing is playing.

Maybe a box like this is cheap there days ? And modify & connect it to more LEDs ?

(http://www.hestudiotechnik.de/image/midi/rol_mks900_sigInd.jpg)


A weird alternative that will perfectly work if you happen to have some surplus simple hardware around is to trigger both your wanted sound
and another 'dummy sound'  (say an ongoing  1kHz sinewave/pad/loop) in some other module in parallel, so responding both to the same MIDI-note-number.

Say you need eight indiv. LED-indications and your surplus synth/sampler/soundcard has eight outputs.
Route each of the eight each to a separate audio-output and connect a simple signal-present or signal-clip LED to is, circuit to be found here @ GDIY (don't listen to those sounds)

Bye,

  Peter
Title: Re: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigger
Post by: Mbira on May 05, 2009, 10:19:45 PM
You'll then need some decoding of the MIDI-notes into separate LEDs.
That's the part I'm not sure how to do.

Quote
And you'll need some method to extend the LED-on after the trigger has ceased.
You'll probably want to have the LED on as long as the sample/loop/thing is playing.

Not sure if you've used Ableton at all, but what each of these triggers will play is a sort of scene with several clips in the scene.  I could have one of the clips just be sending midi notes out continuously (or as a rhythmic flash ;D).  Each scene could send a different note corresponding to a different led.

So the question is how to make midi notes trigger an LED?

I've seen this:
http://www.jpleisure.co.uk/item117.htm (http://www.jpleisure.co.uk/item117.htm)

which is eventually where I want to get (controlling lighting through the Ableton as well...but not sure if there is a quick and fast way to get this aspect working.
Title: Re: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigger
Post by: Svart on May 05, 2009, 11:25:39 PM
the peizo elements in those triggers produce a voltage spike when vibrated.  Use some zener diodes, some fets and a handful of resistors and you can trigger the LEDs directly without all of that fancy stuff..

Title: Re: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigger
Post by: Mbira on May 05, 2009, 11:30:33 PM
But then how would you keep the LED lit after the strike, and how would the LED turn off after the next hit on a different pad?

Title: Re: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigger
Post by: Svart on May 05, 2009, 11:34:47 PM
well your initial post didn't mention that!   ;D

Title: Re: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigger
Post by: Mbira on May 05, 2009, 11:37:07 PM
 ;D
Title: Re: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigger
Post by: PRR on May 06, 2009, 01:46:05 AM
I do NOT go over to that side of the shop, but I believe that lighting systems are (or were) MIDI controlled.

Then you get an old 8-in(*) MIDI light-board, program it so that the code for "pad 1 hit" triggers a "lamp 1 ON" event, etc. Plug in some little night-lights (or LEDs with serious dropping resistors).

(*) You say nine, but 8 may be a stock size, and if you get the first 8 right then 9 may happen OK.
Title: Re: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigger
Post by: clintrubber on May 06, 2009, 08:37:04 AM
But then how would you keep the LED lit after the strike, and how would the LED turn off after the next hit on a different pad?



Sound like a nice application for a 555 timer-IC per pad: configure it as a one-shot to extend the lighting and reset it when one of the other pads is hit. So the reset for each is looking at the other (say) seven pads, performing in fact an OR-function (might be possible simply by diodes, didn't check) 

While a simple principle, it still looks like quite some soldering though. How about having a look yourselves at the Ableton-output ? Or is what's to come next not obvious from looking at the current clip ? (looks like it's indeed so, otherwise you wouldn't have started this thread  ;))

Bye
Title: Re: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigg
Post by: mikep on May 06, 2009, 08:56:12 AM
Since you really want to know if the midi brain recognized the trigger, no variation of detecting the analog pulse raw trigger output is appropriate. I would use a cheap little pic microcontroller to read the midi data and drive LEDs.  Software will interpret which trigger was hit, control how long the LEDs stay lit, etc.. I bet there is some free c source code floating around on the web that would get you started with dealing with midi.  Course, if you aren't already up to speed with this kind of thing it will take a while.

Mike p
Title: Re: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigger
Post by: Mbira on May 06, 2009, 03:49:34 PM
Ableton can easily send the midi to whatever device will switch on and off LEDs.  Then only rub is finding the controller will turn on an LED with midi info. 

There must be a way to do this without having to run through a midi/dmx converter->dimmer pack->lights.
Title: Re: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigger
Post by: clintrubber on May 06, 2009, 06:34:50 PM

There must be a way to do this without having to run through a midi/dmx converter->dimmer pack->lights.

Continuing on the 'trigger a dummy sound in parallel'-route I described above, how about making those dummy-samples distinct sinewave frequencies ?

Send them all out from an unused single audio-output from the computer (let's assume that's possible, otherwise add the cheapest USB-audio-I/O). Sinewaves can be one-shot triggered samples having the duration as required.

Make those different frequencies cover the full freq-range of your audio-I/O.
For NINE indicators for instance 60 Hz, 120, 240, 480, 960, 1920, 3840, 7680, 15360 Hz
(taking into account bandwidth-limitations of your audio-I/O, and/or shift if you expect massive mains-interference etc)

Using bandpass-filtering in front of a simple LED-clip-stage (say little more than one transistor & LED & some R & C) you can discern between the frequencies. Adjust the sample-levels to finetune. Simple passive filtering might work, otherwise you might need to add one transistor for making it an active bandpassfilter in front of the usual clip-LED-stage.

This should be pretty simple and have low parts count per LED-indicator:
- one or two BJTs
- one diode
- some resistors & caps

If it works well enough you might want too squeeze in more frequencies. And using an audio-interface running at 96kHz sample frequency instantly doubles your amount of possible indicators while maintaining filter-spacing.

If you go the route of making the bandpass filters pretty sharp (say a twin-T in the feedback of an amplif-stage) then note you can finetune the circuit-response by adjusting the sinewave-frequencies to the actually realized filter-frequency (the top). So keep the circuit with its tolerances like it is and adjust at the sinewave-generation side.


Bye,

  Peter   
Title: Re: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigger
Post by: Mbira on May 07, 2009, 12:49:44 AM
I like this idea!  This would be doable with my equipment.  If I'm understanding, this would be like building a "feedback detector"?
Title: Re: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigger
Post by: clintrubber on May 07, 2009, 06:45:43 AM
I like this idea!  This would be doable with my equipment.  If I'm understanding, this would be like building a "feedback detector"?
Nice, good to hear this might suit your needs. Note that if you have one audio-output to spare you probably have a second channel available as well, which will make the filtering less critical (using panning, it allows to spread out the freqeuncies more) and/or allows more frequencies(=LEDs).

yep, it basically comes down to spotting frequencies. If you put them at the ISO-freqs you could do without soldering & watch an RTA-box during gigging'n'jumping. if you can find one cheap you could actually use such a beast for the filtering & mount the LEDs where they suit you best.

Bye,

  Peter
Title: Re: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigg
Post by: mikep on May 07, 2009, 08:28:08 AM
Yes! Good idea. You don't need to build anything. Feed the sinewaves into a cheap 3rd octave RTA.
Title: Re: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigg
Post by: JohnRoberts on May 07, 2009, 09:45:36 AM
I like this idea!  This would be doable with my equipment.  If I'm understanding, this would be like building a "feedback detector"?

While I don't know what this has to do with the original question.. here is how to do feedback detector.

http://www.google.com/patents?id=YrwaAAAAEBAJ&dq=john+roberts+visual+indication+of+feedback

Back in the '80s I did several midi control products (at Peavey) and we even sold a relay box that could be controlled by midi, surely this stuff is still out there. As I recall the relay box, hung off some other product so it was not a very cost effective solution, even if you could still find one.

JR 
Title: Re: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigg
Post by: clintrubber on May 07, 2009, 05:31:02 PM

While I don't know what this has to do with the original question.. here is how to do feedback detector.

http://www.google.com/patents?id=YrwaAAAAEBAJ&dq=john+roberts+visual+indication+of+feedback
 

Hi,

Use of feedback-detector to answer Mbiras need as explained earlier on in this thread.

The JR-patent a possible circuit for the implementation. (while already economical, maybe even less soldering and/or cheaper with a circuit that uses a BJT i.s.o. the opamp ?)

Maybe JR can help Mbira with component values for each band ?


Bye,

  Peter
Title: Re: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigg
Post by: JohnRoberts on May 08, 2009, 10:35:32 AM
I suspect I charge way too much for my circuit design services (if I was even looking for work),  :D but it seems there should be some off the shelf solution.

I recall midi to relay closure decades ago... while not very cheap.  The specific box was called an EAC-8, but that was just the relays, and needed to plug into another piece of midi rack gear, to control the relays. A lot of work for a few LEDs.

This could probably be accomplished with a $2 PIC and a few transistors, but I don't write custom code either. Midi is pretty mature, have you done an exhaustive search, maybe look at some obsolete gear?

JR
Title: Re: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigger
Post by: Joechris on May 08, 2009, 02:05:33 PM
Maybe the Doepfer MTC64 will do the thing.
http://www.doepfer.de/home_e.htm

j
Title: Re: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigger
Post by: Mbira on May 08, 2009, 02:20:11 PM
Yeah, It seems like this is much more complex than what I'm needing.  I figured it'd be easy to have something receive a midi signal and light an LED.  Eventually, we'll be going the midi/dmx converter way for a light show at which time I can probably easily impliment this with mini lightbulbs.  In the meantime, I just need to use my memory.
Title: Re: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigger
Post by: Freq Band on May 17, 2009, 04:59:34 AM
OMG...they're still alive...

http://www.midisolutions.com/products.htm


=fb=
Title: Re: Can you suggest an easy and inexpensive way? Triggering LEDS with drum trigger
Post by: Mbira on May 23, 2009, 08:38:49 PM
Well I'm a little further along on this journey...

I must say that I'm very impressed with Ableton and their customer support.  They have been generally fast to answer and willing to talk about something that is clearly outside of their normal product line...

Anyway, it looks like There is a built in midi feedback message that occurs whenever these clips are triggered.  Here is the response I got:

Quote
Live will respond with the following MIDI messages when a message has been mapped on a clip:

a) clip has been triggered but is not yet playing:

message type: NOTE ON
velocity: 126

b) clip is playing:

message type: NOTE ON
velocity: 127

c) clip is looping:

message type: NOTE ON
velocity: 1

d) clip has been stopped:

message type: NOTE OFF
velocity: 0

The note number as well as the MIDI channel are always identical with the note/channel you mapped on the clip.

The get the feedback sent from Live, simply enable the "REMOTE" button on one of the MIDI output ports (in the MIDI/SYNC preferences pane).

If you own Max/MSP or have a friend who can program a stand-alone Max patch for you, then you could build a simple patch which displays a large LED that responds to the aforementioned MIDI messages from Live.

I have made these feedback notes work...now it seems like just a matter of converting these messages into voltage that can control LEDs?