Cell Phone to Sound Board for only $20!

I have successfully finished yet another garage-shop electronics project that actually WORKS!

Tuesday, Pastor Mike at Rez announced that in two weeks, when they're on their short-term missions trip to India, they'll be performing yet another Skype call in to 6:33 pm. However, the last two or three times they've been anywhere, they've tried this, and every time it's been a rig. Here's how they did it: a laptop on their end runs Skype, the Mac computer on our end runs Skype, but the bandwidth is low enough that we can only manage video. The audio cuts in and out. So for audio, we do a regular cellphone call (and use the headphone jack on the phone to pipe it into the sound board at church). And on top of that, we relied on the built-in mic in the cell phone to pick up any audio for the overseas guys to hear. A really poor setup to say the least. And each time, I've promised to come up with a better solution for next time.

Well, I finally did. After 3+ skype calls, I finally broke down and built a phone to generic audio converter box. This basically takes the standard 4-conductor headphone jack that plugs into any modern phone for hands-free devices, and converts all three circuits into ¼" monoral TRS jacks. These jacks are left and right headphone audio out, and microphone in.

It took a little more than just straight wires on the microphone, simply because the output from nearly any audio device (except for a real microphone) are going to be a lower impedance than the input on the cell phone can handle, so I had to dumb it down with resistors. With some help from my dad making a few modifications to my schematic, I was able to solder and wire everything up yesterday, and then just an hour ago, I managed to find a workable solution to hook it up to my computer at home and make it all work. And yes, it did work! I called my mom on her phone while the box was plugged into mine, and I was able to speak into a big microphone and she heard me, and then I hooked the audio out to my computer and I was able to hear (and even record) her over my computer speakers. YES!!

One of my biggest goals for this particular project was making sure that all the connections were well insulated and well soldered in. I have made several projects that had pretty poor solder joints and were always giving out. I didn't want that to happen this time. So I made sure that all of my leads were long enough and that there were no nicks in any of the wires. It seems to be solid! Everything works beautifully and there are no shorts anywhere.

My BIGGEST problem was soldering up the 4-conductor surface mount headphone jack. This was one type of thing I could not for the life of me find instructions on how to do. Nor was I expecting it to be that difficult. But the device was I think ROHS-compliant and thus did not take regular solder all that well. Besides that, I didn't have a fine-tip solder iron, nor any fine-pitch solder. I don't have the money for a $400+ Weller. All I have is a 40 watt radio shack iron.

Well the solution I came up with was to just completely remove the plastic insulation from around the four conductors on the headphone jack and then just wrap around the single-strand cat5 wire around each of them and solder them into place. Once hot enough, the solder flowed fairly well and I didn't have any big problems after that.

Actually I did have one minor problem, but that's when I fell in love with hot glue. After soldering up those wires to the 4-conductor headphone plug, I found that I needed to insulate them from one another. But I didn't have any 1/8" heat shrink, so I decided to use what I saw one tutorial on the web use: hot glue! With a toothpick I was able to get a little glob of melted glue down between all of the leads on the headphone jack. But then the ground tab didn't want to bend back in all the way (and make room for the black plastic housing), so I just pushed the housing as far on as it would go and then glued that in place as well.

On top of using hot glue to pretty much epoxy the entire plug assembly shut, I also used it to stress-relieve the hole in the box where the wires for the plug were coming through. Since I used a drill to come through the main plastic project box, there were rough edges which would eventually have worn through the insulation on the wires. No longer. They're glued in!

Lastly, I used perfboard to wire in the microphone volume control and other impedance-matching components including a 1uF capacitor to remove DC offset on the line. Works great! The potentiometer I drilled into the side of the box opposite the headphone plug. Then on an adjacent side, I drilled in the three ¼" TRS jacks, 2 for audio out, 1 for audio in.

With all of this in place, I will be able to take three patch cables and connect them between my box and an audio input and output on the sound board. Since the group is going to do their thing in TWO weeks, I'll be able to go in next Tuesday and do a test run with Dad. I'll hook up either his phone or my phone and we'll test it out with the other in the other room/other end of the building. The goal will be to communicate with the remote phone via the large speakers and a hand-held mic, both of which feed into the big sound board.

 

Is this how they do it on radio with making calls in? Sure. But some company has probably made this sort of thing a lot cleaner and flawless. However, I made it myself and it works! And it only cost me $20. Well…besides the box, which I already had from another project years ago. But yes! It works!! And if I can get my own patch cables at home, I'll be able to record YOU when YOU call me! Or maybe phone interviews or anything else! So excited that this actually works. HA!

More on Skype and overhead setups

Well, last night at men's 6:33 we had our Skype call from Argentina. And it worked...kind of. However, the connection they had down there was extremely poor and our own LAN wasn't doing so hot for external connections either. However, we did like we had done for when they went to India. We bypassed audio transmission and sent only video through Skype. Then we plugged someone's Blackberry into the sound board via headphone jack and were able to get audio that way. So Skype for video and Blackberry for audio. It worked fairly well and we were able to get a decent show up on the screen.

However, WE of course, were stressing out the entire time and we had leadership up in the sound booth bugging us as to why we weren't getting this feature to work or why they couldn't hear us or why why why...

And of course, we didn't know because we hadn't anticipated the Blackberry/cell-phone idea one bit. They just handed us the cell phone and said, "This is how we did it this morning!" But neither of us were there "this morning," so we had to figure out what they were talking about. Anyway, the same leadership person that was pretty much instigating all the stress also said afterward that we should just come up with a standard. He said, "Skype team," but I assume that to mean that we just need to write up a whitepaper or standard on how to make Skype work for missions trips that we want to bring in during a service. And I've come up with a few ideas.

The first idea is to codify the setup we had last night. Have a headphone plugin going to a cell phone from the board for audio and Skype the video in and combine them successfully. However, Skype, I noticed, is pretty horrible with video, especially when the camera is low resolution. Besides that, we only have a framerate of maybe 2 frames/sec if the connection is good and less if the connection is bad or flaky. In fact, there were times where we had 1 frame/2 minutes last night.

So maybe we should scrap the Skype idea and go for something a bit more reasonable like UStream. UStream is like an online video recorder that will also stream your recording live as you record it. Of course, I've no idea what the quality of the transmission would be if they were on a slow connection, so this might require a bit of thought.

As for audio, working with everybody else's cell phone was just horrible. The first one we got was a flip-phone that required security unlocks due to the international connection and it kept disconnecting on us. The second was a Blackberry and we got audio okay, but had a bit of trouble sending audio back. Besides that, the guy was up in the sound booth yelling at his phone the whole time. Thus I've come up with a solution. Perhaps the best idea would be to create/research a box which would replace the telephone handset. We DO have a landline in the sound booth which we can probably more easily call and get a reasonable connection (cell phones either way increase chances of dropped calls). My idea is to somehow vandalize or 'decompile' the telephone handset which is on a PBX network and replace it with a plain old RCA I/O. This would require a bit of impedance matching and possibly some audio amplifiers to interface the phone earpiece/mic with a regular audio input/output. This is probably the best solution that I can think of. Of course, the store-bought one costs somewhere around $400, so that's out. I can't imagine a church paying that much money for a once-a-year occurrence. Besides, I think I can make my own, with my dad's help.

So those are my ideas and reflections. I didn't think last night was at all efficient, and standardizing it will make things a whole bunch better.

Idea for new computer

So we're having this BIG thing at church where a group of probably seven to ten guys are going down to Argentina in about a month or so. They're trying to set it up so that the Tuesday when we're meeting and they are gone, they'll Skype us during service and we'll be able to put it up and talk with them live. I think this is pretty cool. However, we were running into a few security bugs last week when we tested (security locked me out of being able to open Skype up). We'll be testing it again tomorrow night, and I think the IT guy at church fixed it. Anyway, he said he'd look into it this last week.

This all got me to thinking: what would be the ultimate media computer? I thought, everybody goes for Mac as a media computer, but what if I were to just completely create my own? I thought I'd probably use Windows as an operating system, since I know that one best. However, the very basic distribution has SO many background processes to keep everything running it's almost annoying. But I think I'd go for Windows in spight of everything.

Actually, my idea was this: what kind of computer could I build that would be the ultimate in speed, capacity and technology while being affordable? And what kind of cool peripherals could I put on it to make it completely media and Internet-based? I thought, maybe I'd create a whitebox (custom desktop) computer with all the latest video/audio hardware. I'd have a nice big GEForce or NVidia video card plus maybe a 6-channel audio card. Of course, I'd also have the option to mix everything down into 2-channel stereo, but 6 channel would be nice to have just in case. On top of that, I might try to set it up with three monitors. Yes, two is cool but three is cooler!

Then I thought maybe I'd get a permanent webcam and possibly attach it with a Third Hand sort of mechanical device. Maybe ball joints or something. I also thought that maybe I could manage a good quality scan converter so I could pipe one of the monitor outputs to a composite video feed.

Of course, I also considered making it portable. Maybe a nicely carved wooden box or a steel crate with air vents would be sufficient to cart it around. Or I could go for one of those official media boxes with the twist-clamps. Also, a box would mean casters, because with all this stuff I'd add to it, it would become quite heavy.

Let me go back to audio. I'd also want a fairly decent audio mixer so that I could control volume of the output audio. And probably I'd want another for inputs.

I'm probably going crazy here and have racked up around $3000 worth of stuff...but I'll keep brainstorming.

Of course, I'd have a high-quality (everything is high-quality) network module or two..wireless and wired. And maybe a dialup modem, since we're still on a phone line at home.

Actually I should put this all in perspective. This was an attempt at making the ultimate Skype experience. Webcam, audio input and output and a video output for the overhead projector setup we have at church.

I seem to be rambling. But of course, I'm into it! This is what I'd do if I could. Of course, at the moment I can't but if I COULD...yeah.

Then I have to think about weight. So far, I've really really enjoyed having a laptop to cart around everywhere. It's VERY portable. I couldn't imagine taking this giant box to the library every day for school..of course, who says this is a school computer? I don't want to store EVERYTHING I ever have had on this thing. That would clog it up and it's primary purpose would be bogged down. No. It's only for media broadcasting and stuff.

I just had another brainstorm: video inputs? Maybe. Maybe not. That's a tossup. All of the video stuff I've seen so far is HUGE and that'd detract from the good speed I'd be getting. This is going to take some thought, but I definitely want to look into it.

Okay. I am probably done rambling. Have fun reading!!