Cuphones - Cup Headphones?

Today was kind of interesting for simple side projects. Mark Oscai, a student I work with and regular lab wrecker (just kidding), came in today with something that he had seen in class. I guess one of the ECE 311(Electric and Magnetic Field class) professor, Professor Melloch, did an interesting show and tell with copper wire, magnet, and cup. It would seem Professor Melloch makes a really simple speaker using these things to show how fields work, but I can't really say for sure because my experience with ECE 311 was super boring. Granted, I'm a physics minor and took a more interesting version of the class through the physics department (Phys 330). And by interesting I mean really, really hard. I still had to take ECE 311, but compared to the physics department equivalent it was a breeze.

Anyways, enough boring stuff, here are some of the photos of the materials that were used and just photos as Mark constructed the cup speakers.

As you might expect, the sound wasn't that great so I got the bright idea to add water inside the cup to see if it would dampen some of the noisiness out. The water kind of acted like a low pass filter in the sense that it did in fact dampen the noise, but it also dampened everything except for the muffled bass. It sounded as if you were sitting in the auditorium restroom during a concert. It was pretty interesting.

Here is Mark messing with his magnets and coils to make his speaker work. Mark however is kind of an interesting bird and even though he was able to recreate the speaker working, he still wanted to add some of that Oscai flair to it, which leads us to his revision two of the speaker... or rather... cup headphones.

And just in case you're skeptical of whether or not it works, I have a short video of the device working prior to Mark's... creative headphone revision :)

Sorry about all the background chatter. There were a lot of people really interested in this fun little project. Also, I am sorry once again for vertical videos. I'm not really the best photographer.

Instrument Room Side Projects

A couple of students I work with in the instrument room here at Purdue also have some side projects that they get involved with. Some are just looking for extra experience in soldering and others are just helping out friends.

First up is Travis Garza, I helped oversee his progress to make an FM wireless microphone because he wanted some extra soldering experience. What a go-getter sophomore. All I did was help him learn good soldering techniques, but he did all of this handiwork and I am proud of him even though we weren't able to get it to work.

Second up is Kyle Woodworth, I was not even involved for this project but managed to see his handiwork just as he finished so I only have a few photos at the tail end. One of his friends asked if he could do a fixer-upper for his Gamecube controllers. (I guess his friend is really involved with Super Smash Bros.) According to Kyle, which didn't take photos of his progress, this controller was 80% nasty and 20% super gross so I'm impressed with his cleaning and re-soldering. Allegedly, the capacitive coupling can be reduced thus increasing the response time for these controllers according to Todd Wild (my overseer, in Todd we trust).

 

Repairing HP 3310A Function Generator

It is not uncommon that lab TA's report that their lab equipment is broken in some way or another. Usually it's some trivial thing like they forgot to check if it's properly powered or didn't know how to check if the fuse is blown, but from time to time the equipment is in need of some serious maintenance.

So this was brought into the back and the TA just mentioned that he couldn't get it to work. This older model function generator are usually pretty solid and don't have fuses so if they're broken then they are super broken. After some initial tests just to double check if the TA was not using it correctly, it was found that there was no output for any of the waves.

After taking the thing apart, and I would just like to give kudos to HP for their work in designing their function generator in such a way that it was a huge pain to take apart. I mean this this is a rock solid piece of equipment and my guess is they really didn't want it to be taken apart unless it really had to because it was a mystery box of sliding parts to get this jigsaw box apart. Anyways, it is pretty common for the countless detaching and reattaching of cables to the output by students just naturally wears them down and in this particular case, breaks the connection so that new leads need to be soldered. To the right, there is my handiwork with a new resistor in place. The original connector that was attached was just destroyed so I had to fashion a new connector to the board as well. This actually solved part of the problem because I was able to get the function generator to output a square wave, but the Sine and Triangle wave parts were still flat lining.

Well that was the easy task, now I had to look for something a little more malicious as to why this thing wasn't working and you can see it in this picture to the left. Some old military grade tantalum capacitors leaked and corroded away at the copper trace. On the right you can see that the trace was just eaten away.

So the service manual was found, but wasn't really necessary in this particular case because it was fairly obvious what was the culprit for the bunk outputs. I thought it was kind of interesting though and figured I would show the photo of the schematic, C2 and C3 should be the caps that I needed to replace if I remember correctly.

The only thing that needed to be done to repair this would be to fly wire the two separated traces together and drop in some new tantalum capacitors. Not too tricky.

The above photo is the new wire soldered to connect the two traces, and to the right are the new two orange caps that were soldered in.

And would you know it, everything started working again. Successful repair job to keep this HP function generator up and going for at least another year before someone drops it or something.

Big thanks to Dave Azpell for keeping the service manual and giving me guidance on what to check for to get this guy up and running again.

Update About Myself

So I've been working with Purdue University in the instrumentation room. My job title is Analog Lab Manager. It sounds super fancy and it kind of is. I oversee all undergrad EE labs ranging from sophomore year to senior design for undergraduate engineers. I often fix scientific equipment from oscilloscopes to function generators. I also provide design guidance for seniors in senior design on how to accomplish projects.

As a disclaimer, my views do not necessarily reflect the views of my employer and if there should ever be any questions, please email me.

I do not really like talking about myself all that much and would rather let my engineering prowess speak for itself instead of using sparkly words and posturing to make myself appear superior to my engineering brothers and sisters that worked just as hard as I did.

I am an excellent team leader and work best in teams that prefer open communication to promote excellent brainstorming and design creation. When I get involved in a project I want to think that every team member wants to be involved and want to accomplish the task for themselves and not for a paycheck or grade. Because of this, I tend to expect a lot from team members, but truly I wish that each member on my team feels appreciated for their contributions.

I mostly wanted to post a little bit about where I work and what I do at Purdue University now, but got a little sidetracked with talking about myself a little more than I expected. My current goals now are just build projects for myself to showcase some of my skills, and work my way into the blessings of a professor that would take me on for graduate school.

Elenco AM Radio Kit - Model AM 780

The other day at work I found some Elenco AM Radio Kits in the way back of the instrument room. It appears to be 16 years old, but there isn't any definitive date on this kit. This was a really simple kit and they provided everything including the solder. I only skimmed the instructions on a few sections of the radio because with this particular kit any entry level electrical engineer or technician would be able to see the schematic and populate the board.

The whole mini-project took about an hour for myself and this was pretty fun thing to do during a lull at work when none of the equipment was "broken". This post is probably just going to be photos and a short video showing that the kit works fairly well. It works pretty well even inside, but in fairness, Purdue has WBAA AM 920 on campus.

These are some of the photos that I took during the progress and following is the video I took that it actually works.

 

 UGHH, I'm so sorry I took a vertical video:(