hpr-knowledge-base/hpr_transcripts/hpr3478.txt

Episode: 3478
Title: HPR3478: Audio Wiring Hack on a Classroom Podium
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr3478/hpr3478.mp3
Transcribed: 2025-10-25 00:08:13

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This is Haka Public Radio Episode 3478 for Wednesday 1st of December 2021.
Today's show is entitled, audio wiring Haka on a classroom podium.
It is hosted by John Colbe, and is about 18 minutes long, and carries a clean flag.
The summer is, listen in while I Haka the wiring on our classroom podium for custom audio routing.
Hey everybody, this is John Colbe in Lafayette, Louisiana, and I'm coming to you from my classroom
where I teach during the week, I'm coming on a Saturday because I'm coming in here to
do some hacking appropriate to talk about this for Haka Public Radio.
I would think what I need to do is some custom wiring in the podium because somebody
undid my custom wiring that I had done before in the podium, and the custom wiring I'm talking
about has to do with audio routing. So I teach music history, and there are many occasions where
I want to be able to show a musical score using the document camera, which is a, it's in this
big drawer on the side of the podium. Some people might know these as an Elmo visual presenter.
So essentially a thing where you stick a book or something down on there, and it will be displayed
on the screen at the front of the classroom. So I want to be able to display a score on the screen,
but play audio from my laptop at the same time, and the way it's wired right now, that's not
possible because each item on the switcher, which is a, it's like the brain of the operations,
it is an extra switcher with, it looks like eight possible inputs, and for each input there is
video and audio, and when you are, when you've selected the document camera, it only will play
audio from the document camera, but of course there's no audio playing from the document camera.
And so you don't hear anything if you're playing audio from your laptop through the VGA input,
and so what I've done in the past is put in some little wired jumpers from one input to the other
in the back of this thing, and the last time they upgraded something in this classroom they
undid my work, and so now I can't do what I want to, and so I'm coming on a Saturday to try to
sort this out. So what I need to do is go from, right now it is, the VGA selected that is apparently
channel one on the extra one. So I want to run audio jumpers from that to the document camera,
and I've selected the document camera, that is number two. So right now it looks like,
it looks like there's nothing in slot two, when it comes to the analog inputs, and so hang on,
what's number four? I think that's probably the Dell computer, and I'm going to press PC,
yeah that's channel four. So I'm going to press document camera again, that's channel two.
Thankfully there is a spare connector that somebody has left in here that I think will serve my
purposes. I'll take a picture of the connector, get the camera out, these are pretty cool little
connectors. They're little plastic connectors that have five slots in them, and the slots are for
various things, I should probably. There are audio and video slots, and maybe remote control slots,
I'm not really sure. I'm going to take a picture of this one up here, so I can see where the audio
ones go. It looks like left channel is slot one, and right channel is slot four.
So what I have to do is remove the one that's in there for channel one, that is the VGA,
like external VGA thing, and then cut a couple of little jumper wires. Let's say I'll do the red one
for the right channel, and then maybe yellow for the, what the heck happened to me.
I don't need very much wire here, just a couple inches, but I'll do probably six or eight inches.
Okay, there's a red one, let's cut a yellow one, strip a little bit off of each end of each wire.
Maybe strip a little bit more off of there.
When I, when they came to upgrade the switcher the last time I told them, please don't mess around
with my custom wiring, or if you do, please replace it with something equivalent, and I think
the technicians just either didn't want to or forgot or whatever. They don't have the same concerns
that I have. Their concern is getting it up and running according to their usual methods. My
concern as a music history professor is to be able to show scores. Now I mean the work around
of that is of course having something like a PDF score on my laptop where I can play the audio
from the laptop and show the PDF at the same time. However, I don't always have a PDF
and so, man this looks different, that's somehow. I'm looking at the connectors they've got in here.
Okay, well this should do. I don't always have a PDF or I don't have time to make one before class
and so I need to just grab a book and bring it with me, but that's not always possible. Okay,
I need my tiny screwdriver. What I'm doing now is I'm going to put, oops sounds too big.
I'm going to put the yellow left channel wire. I hope this works. So channel two right now is where
the document camera is and it looks like they're using. What are they doing here?
Where's that one going? I can't see exactly where it's going. They've got it routed somehow for
the video but they've cut off the audio cable which irritates me. I wish they would have left it
there but whatever. I think what I'm about to do is going to work but we'll test it before I'm
done recording and that will that will tell us for sure. Okay, so channel one and channel four.
I'm going to slide the yellow one into slot one and then I've got to tighten down a little screw.
These connectors you've got tiny little wires and then little screws that hold the wires in place.
The connectors that they have in there right now have these excellent little places to put
strain relief so that you can't accidentally yank the cable out there but this spare connector
that I found in the bottom of a cabin that does not have it and so I'm hopeful that I hope I can
make it work without accidentally pulling out the the work I've done. Shoot.
Maybe I should undo this. Pull out the fan. Got noisy.
Not the easiest thing getting these tiny wires.
Okay, you stay put while I screw it down.
Okay, oopsie. Man, the yellow one has got some stray wires that have popped out and going into
the next channel over which I don't know if it would do anything bad or not but I'm going to try to fix it real quick.
It probably wouldn't matter.
Okay, I'll put you back in there. Put you back in there.
Now tighten it back down.
Okay. All right, so I've got my little jumper one ready. I'll take a picture of that.
Now what I need to do is pull out this other one.
Okay, got the other one out. I'll take a picture of that one too.
Sounds like somebody's coming in here.
Now maybe it's just a student out in the hallway getting into a locker.
Okay, so now I've got to try to double up these wires on this other one.
So the one that was already plugged in there will now have on the white one.
It'll have also a yellow one under there with it to jump it over.
The little jumper wires that I'm using are very thin so they don't have a lot of strength to get in there.
I'm going to bend that over and wrap it up a little.
Go on in there, you.
I'm pulling out the white one just a little bit to jam the yellow one in there with it and then shove them both back in.
The white one that's in here already is a slightly thicker, heavier gauge of wire.
And so it's taking up too much space. So I'm going to try to put these two together and then shove it back in.
So hopefully I don't mess the whole thing up all together.
Okay, that's that one. I'll do the red wire.
Loosing up the connector.
Actually, I wonder if that's the right one.
Now I see a black and a red here. I wonder if the white one is like some kind of
neutral thing and the black and the red are the ones I really should be doing.
Well, I'll find out. It looks like though on the diagram on the unit itself, it says
that I'm doing this right. We will see.
I kind of wish I could take it off for just a moment while I do this and then put it back on.
Very delicate work here.
You got big clumsy hands like mine. It's hard to get in these tiny, tiny little spaces with these
ety-bitty wires.
Go on in there, you.
Okay, let's see if that does it.
All right, so now the two things are connected.
I'll take a picture of that and plug this one back in where I found it.
In slot one and this one in the slot two.
Oopsy, slot two is down there.
Doesn't help that this stuff is way down low on the ground.
Okay, it's in there now. Now time to test it. First, I'll take a picture.
And then I will test.
So I've got the document camera out. Let's turn it on.
I don't know if that's even necessary really, but what the heck?
Okay, now I will plug in. Actually, I turn on my laptop real quick.
Plug the VGA inputs audio cable into my laptop.
Make sure the volume is good and try to play some music.
Don't worry, Ken, I'm going to play something that is in the public domain.
Now let's do prelude in C-sharp minor.
Oh, yes, there it is.
Okay, can you hear it?
That's coming out of the speakers.
While the document camera is selected and now I'm going to select the VGA and it should
after breed pause do the same thing. Yes, okay, I am back in business, y'all.
And that is how you can hack your podium to get audio at the same time as you're showing
something on the document camera. Victory is mine. Talk to you all next time.
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