Tech Tales: The Graveyard Memorial ProjectBy Tony Green
A customer walked into Jameco's office recently looking for technical advice and part recommendations for his art project. He is a San Francisco Bay Area sculptor who was working on a project to memorialize the departed in a graveyard, recently discovered under a town square in a small town in Germany.
He was consigned to create an audio effect for a German graveyard. The idea was to create a small device that would play audio in a loud whisper reciting the names of the deceased in an endless loop. To accomplish this he needed a device that was self-powered, have to ability to run for months unattended and be buried somewhere in the town square. I asked if he realizes that it would be very a creepy experience to hear that, especially alone and at night. He laughed and nodded excitedly saying that’s exactly what he is going for.
As an artist, the customer had almost no electronics knowledge and only had six weeks to get it built and installed. No problem, Jameco to the rescue! Since he had almost no time left to the rapidly approaching due date, I suggested he go with off-the-shelf commercial components as much as possible and kits if necessary, rather than design and build the whole thing from scratch.
I suggested he start with a recording/playback device. Something like an iPod, but a Walkman or MP3 player would also work. An external speaker he can place as close as possible to the surface. If the playback device is loud enough, we need to immediately calculate how much ampacity he'll need from a battery pack. And the customer will almost certainly have to assemble the battery pack himself.
I warned him we are probably looking at automotive type batteries. Lead acid would work but Lithium Iron Phosphate (LiFePO4) would probably be better. Local utility power, a generator and solar recharging are apparently not an option. I recommended a couple of speakers, explained how to wire them in, and he was off to buy an iPod or something similar.
The very next day he was back with an iPod, a rats nest of wiring, the two speakers and a sad face. He explained that he wired everything up exactly as I suggested, and it just wouldn't work. First getting his permission to debug this lash up, I start pulling off tape and separating wires. Quickly locating and fixing the shorts at each speaker, I ask him to power it up and we had music!
Although initially excited, he grew sad again because the sound was not loud enough. Not surprised, I reminded him that I warned him that was probable and explained how we could fix it with an amplifier.
It immediately turned his frown upside down. I showed him some amplifier kit options. To save time I suggested checking with some musical instrument vendors for an off the shelf amplifier or small PA system.
I asked him again about any line power options at the town square to avoid any battery issues. There were none that he knew of, however I suggested he Google map the area and see what was around and to also contact his customer.
The very next day he was back with a new, fairly compact mono-amp PA type system. He also discovered the line power source at the site. He did run into a wrinkle with a representative from the town who requested that the installation only worked during basically daylight hours (too scary?). Our customer solved this easily by adding a light timer. In addition he wanted to add a feature that let the audio play for a certain period of time then go silent for about an hour and then automatically restart again. I suggested a Velleman timer kit, or possibly a lab timer he could get from a laboratory supply company.
The last I heard from our customer, he wanted to list me and Jameco as contributors to his project. I'm looking forward to hearing and seeing photos of how the project turned out and hope that no one gets too frightened by the project.
Tony Green majored in Aeronautics and Aerospace Design at San Mateo Community College. Before coming to Jameco in 2011, he was an Electronics Technician / Automation Engineer at Genentech, Inc., in the engineering and product development divisions, supporting drug manufacturing and development. He was also an Electronics Technician at B. Braun AG, in West Germany. His hobbies are restoring classic Corvettes and relentlessly spoiling his grandkids.