Fail of the Week: Sonar Submersibility Sealing

sonar failFor the last decade or so, [Jason] has wanted to build an underwater robot. Can you blame him? More recently, he’s been researching sonar sensing and experimenting with the relatively inexpensive HC-SR04 module. Since he had good luck getting it to work with a PC sound card and a Stellaris Launchpad, he figured it was time to try using it underwater.

Hydrophone research led him to the idea of submerging the sensor in mineral water oil to both seal it and couple it with the water. Unfortunately, the HC-SR04 only sends one pulse and waits for echo. Through the air, it reliably and repeatedly returned a small value. Once inside a pill bottle filled with mineral oil, though, it does something pretty strange: it fluctuates between sending back a very small value and an enormous value. This behavior has him stumped, so he’s going to go back to the Launchpad unless you can help him figure out what’s going on. Should he use a different method to seal it?


2013-09-05-Hackaday-Fail-tips-tileFail of the Week is a Hackaday column which runs every Thursday. Help keep the fun rolling by writing about your past failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.

Displaying bubbles in mineral oil

After he saw a ‘falling water display,’ [Matt] figured he could turn that idea on its head. He built a display that uses bubbles for pixels. Even though the build isn’t complete, we love the results so far.

[Matt] began his build constructing a tall, thin water tank out of acrylic. Eight solenoids were mounted in the base of the tank, attached to an aquarium air supply, plastic tubing, and one way valves. The first run of the bubble display didn’t go too well, but after adding dividers between each column the display started working.

With the dividers, [Matt] no longer had to worry about bubbles colliding or moving any direction but up. The bubbles weren’t moving consistently, so he replaced the water with mineral oil. Oil made a huge improvement, but the bubbles still float up at different speeds. [Matt] ascribes this to the unregulated air supply, but we’re thinking this problem could be mitigated with glycerine like the previous bubble display we saw.

It may still have some problems, but we love the result. Check out the video of bubbles in mineral oil after the break.

[Read more...]

Follow

Get every new post delivered to your Inbox.

Join 96,534 other followers