Pressure sensor triggers

318 views
Skip to first unread message

Andy Evan Cohen

unread,
Feb 23, 2021, 5:07:43 PM2/23/21
to QLab

Hi all- slightly tangential to QLab, but I figured this would be a helpful form for my question.

I'm building an installation where there will be a coat-rack (or hat-rack) with a set of headphones hanging on it. I'd like to be able to trigger QLab (through OSC/MIDI/other data) through the movements of the headphones: when the headphones are removed from the rack, a certain sequence is triggered in QLab, and when the headphones are returned, a different sequence is triggered.

I'm very familiar with using the various triggers in QLab so the QLab programming is the easy part for me. What I'd love advice for is what type of physical triggers/sensors work best for this project. I'm only familiar with pressure plates or drum pads which send data when hit or tapped, and here it will need to be something sensitive to weight (ideally in a vertical orientation) which will be able to send different values depending on a weight change (as opposed to a continuous controller type sensor.)

What is the type of pressure trigger/sensor I would need? Is it something which can be ordered as a complete unit, or would I need to build it from individual components? Would I need to go through an Arduino or is there something which can send MIDI data (or even ASCII values like page up/down) without the need for a separate processing unit?

I'd appreciate advice from anyone who has built something like this before!

Joe Wilson

unread,
Feb 25, 2021, 3:00:25 PM2/25/21
to ql...@googlegroups.com
I haven't seen an answer to this yet, so here's one from me.

Get a MIDI Solutions Footswitch Controller and wire it up to a reed switch or similar on the headphone hanger.
The footswitch controller will take a contact closure and turn it into a MIDI message, which you can then pass to qLab through an interface.

Cheers!
~joe

--
Contact support anytime: sup...@figure53.com
Follow QLab on Twitter: https://twitter.com/QLabApp
User Group Code of Conduct: https://qlab.app/code-of-conduct/
---
You received this message because you are subscribed to the Google Groups "QLab" group.
To unsubscribe from this group and stop receiving emails from it, send an email to qlab+uns...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/qlab/460e2ab3-b6cc-492c-bb48-a42e0b834f41n%40googlegroups.com.


--
_________________________
Joe Wilson, ATD/Sound
Indian River State College

Adding one more "me too" to the
collective internet consciousness.

Kevin Thurber

unread,
Feb 26, 2021, 11:39:44 AM2/26/21
to QLab
If you can find something that will trigger a contact closure I agree that the Midi Solutions footswitch box would be a great solution but you'd be a bit limited in how it triggers if the reed switch didn't work, you'd have to build some kind of circuit that has sensors and relays. Instead of building your system around that I think going the arduino style route will be cheaper and more flexible.

There are a lot of different sensors you could use and this guide seems like it covers quite a few, the base components are pretty cheap most of the time so you can probably order a couple of each and figure out what would work best for the 'headphone on a rack' situation, if it's a load cell or a light sensor or a motion sensor 

https://www.instructables.com/Arduino-Sensors-and-MIDI/


I've built Qlab midi triggers based around Teensy boards before but it's been quite a few years and I don't think I've retained any of the info but I think I used this guide as a base at the time.

https://ask.audio/articles/how-to-build-a-simple-diy-usb-midi-controller-using-teensy

Let us know how it works out!


- Kevin 

RayZ

unread,
Feb 26, 2021, 6:23:09 PM2/26/21
to QLab
Years ago (+25) I've used a lexicon MRC (if you're lucky you can get one for -40$ on ebay) to do just that with an opcode studio 5 .....if I recall...we could trigger the kurzweil k 2000 sampler using simple on /off trigger switches..you could wire (midi to xlr to midi using audio patch) everything in parallel  so your midi could also be triggered by your keyboard should the CC fail. (it never did)!.....later on, we used the same system to "fail safe" flash pots and "explosions"  it worked really well ...I surely still have some of the switches lying around somewhere....wonder if there is a software only solution nowadays. Bome midi might do this??

Ray

R

James Corner

unread,
Feb 27, 2021, 12:41:35 PM2/27/21
to ql...@googlegroups.com
Take a look at what these guys do

I’ve used their boards with qlab as midi triggers. Lots of possibilities. 
Easy to get your head round. 
Best of luck. 
JC 

On 26 Feb 2021, at 23:23, RayZ <rays...@gmail.com> wrote:

Years ago (+25) I've used a lexicon MRC (if you're lucky you can get one for -40$ on ebay) to do just that with an opcode studio 5 .....if I recall...we could trigger the kurzweil k 2000 sampler using simple on /off trigger switches..you could wire (midi to xlr to midi using audio patch) everything in parallel  so your midi could also be triggered by your keyboard should the CC fail. (it never did)!.....later on, we used the same system to "fail safe" flash pots and "explosions"  it worked really well ...I surely still have some of the switches lying around somewhere....wonder if there is a software only solution nowadays. Bome midi might do this??
--
Contact support anytime: sup...@figure53.com
Follow QLab on Twitter: https://twitter.com/QLabApp
User Group Code of Conduct: https://qlab.app/code-of-conduct/
---
You received this message because you are subscribed to the Google Groups "QLab" group.
To unsubscribe from this group and stop receiving emails from it, send an email to qlab+uns...@googlegroups.com.

James Corner

unread,
Feb 27, 2021, 12:47:30 PM2/27/21
to ql...@googlegroups.com
Sorry I was a bit vague
specifically, take a look at this...
Add touch and proximity sensing to your interactive project with the Touch Board. The Touch Board is a microcontroller board with 12 capacitive touch and proximity electrodes, so you can use it to turn any material or surface into a sensor.
Regards
JC
From: ql...@googlegroups.com <ql...@googlegroups.com> on behalf of James Corner <jamesa...@hotmail.com>
Sent: 27 February 2021 17:41
To: ql...@googlegroups.com <ql...@googlegroups.com>
Subject: Re: [QLab] Re: Pressure sensor triggers
 

Bru

unread,
Feb 27, 2021, 1:18:00 PM2/27/21
to QLab
Hi all
I think I did what you need last year with an Arduino uno and Module Sonar HC-SR04. It was just an experiment (I finally used Arduino triggers for that show) but seems to work pretty well. The Arduino code was quite easy (it was my first program). 
The Arduino is usb plugged an my Mac. You need to install hairless midi serial as usb midi driver for the Arduino. Just route it to Qlab and that's it!
Cheers
Bru
Reply all
Reply to author
Forward
0 new messages