Bats use echolocation to see objects in front of them. They emit an ultrasonic pulse around 20 kHz (and up to 100 kHz) and then sense the pulses as they reflect off an object and back to the bat. It’s the same type of mechanism used by ultrasonic proximity sensors for object-avoidance. Humans (except perhaps the very young ones) can’t hear the ultrasonic pulses since the frequency is too high, but an inexpensive microphone in a simple bat detector could. As it turns out bat detectors are available off the shelf, but where’s the fun in that? So, like any good hacker, [WilkoL] decided to build his own.
[WilkoL’s] design is composed primarily of an electret microphone, microphone preamplifier, CD4040 binary counter, LM386 audio amplifier, and a speaker. Audio signals are analog and their amplitudes vary based on how close the sound is to the microphone. [WilkoL] wanted to pick up bat sounds as far away as possible, so he cranked up the gain of the microphone preamplifier by quite a bit, essentially railing the amplifiers. Since he mostly cares about the frequency of the sound and not the amplitude, he wasn’t concerned about saturating the transistor output.
The CD4040 then divides the signal by a factor of 16, generating an output signal within the audible frequency range of the human ear. A bat signal of 20 kHz divides down to 1.25 kHz and a bat signal of up to 100 kHz divides down to 6.25 kHz.
He was able to test his bat detector with an ultrasonic range finder and by the noise generated from jingling his keychain (apparently there are some pretty non-audible high-frequency components from jingling keys). He hasn’t yet been able to get a recording of his device picking up bats. It has detected bats on a number of occasions, but he was a bit too late to get it on video.
Anyway, we’re definitely looking forward to seeing the bat detector in action! Who knows, maybe he’ll find Batman.
Continue reading “Hack Together Your Own Bat Signal”
In The Dark Knight, Lucius Fox shows Bruce Wayne a neat bit of memory weave fabric. In its resting state, it is a light, flexible material, but when an electrical current is applied, it pops into a pre-programmed shape. That shape could be a tent or a bat-themed paraglider. Science has not caught up to Hollywood in this regard, but the concept has been demonstrated in a material which increases its rigidity up to 318% within one second when placed in a magnetic field. Those numbers do not mean a lot by themselves, but increasing rigidity in a reversible, non-chemical way is noteworthy.
The high-level explanation is that hollow tubes are 3D printed and filled with magnetorheological fluid which becomes more viscous in the presence of a magnet because the ferrous suspended particles bunch up to form chains instead of sliding over one another. Imagine a bike tire filled with gel, and when you need a little extra traction the tire becomes softer, but when you are cruising on a paved trail, the tire becomes as hard as a train wheel to reduce friction. That could be darn handy in more places than building a fast bike.
We don’t know if Batman has a keychain for the keys to the Bat mobile, the Bat copter, and all his other vehicles. But we are guessing if he did, it didn’t look like the one [krishnan793] picked up cheap. It had a little button that lit up some LEDs and played a little tune. [Krishnan] thought he could do better with an ESP8266. After chopping up some headphones and adding a LiPo battery, he wound up with an improved key chain you can see in the video below. The first video is the before video. The second is after the modification. Sure, it is only a small improvement on LEDs and a simple tune, but now it is hackable to do more interesting things if you want to take the trouble to do so.
Continue reading “Quick Robin! The Bat Keychain!”
Xbee sensors at Lowe’s?
Lowe’s, the home improvement big box store, is selling some home automation items which might be Xbee compatible. They’re being sold under the brand name Iris. There is some debate as to whether they’re Xbee, or just 802.15.4 hardware. Either way they might be worth checking out for your wireless projects.
Father sword replica from Conan the Barbarian
Sometimes its just fun to watch the master at work. In this case it’s a blacksmith replicating the sword from Conan the Barbarian. [via Reddit]
LG washing machine that phones home
LG has built an interesting troubleshooting feature into some of their washing machines. This video shows the encoded audio it will output if you use the right button combination. You’re supposed to hold your phone up to the machine while talking to customer service and they’ll be able to get some type of debugging information from the dial-up modem type of sounds. If you end up decoding this audio we want to know about it! [Thanks Pedro]
MicroSD card adapter for Raspberry Pi
[TopHatHacker] was surprised to see a full-sized SD card slot on the Raspberry Pi. His temporary solution to get his microSD card working was to uses a miniSD adapter. He cut away the case and bent the pins until they lined up with the microSD card.
Batman’s cowl for retro motorcycle enthusiasts
Okay, we think this Batman cowl in the style of 1950’s motorcycle garb is pretty cool. Just realize that if you’re seen wearing this you will be thought of as one of the crazy guys in town. [via BoingBoing]
Batman’s ability to fly is a falsehood. Or at least so says science. We didn’t know science was into disproving super-hero movies (that’s a deep well to drink from) but to each his own. But back in December the Journal of Physics Special Topics took on the subject with their scholarly paper entitled Trajectory of a Falling Batman. The equations presented in the two-page white paper may be above your head, but the concepts are not.
It’s not that Batman can’t fly in the way explained in the film. It’s that he can’t land without great bodily harm. By analyzing the cape in this frame of the film, researchers used Batman’s body height to establish wing span and area. The numbers aren’t good. Top speed will reach about 110 km/h with a sustained velocity of 80 km/h. That’s 80 mph at top speed and just under 50 mph when he comes in for a landing.
Oh Batman, how you’ve let us all down. If you liked this paper, you should dig through the archives. We always wondered if [Bruce Willis] could have actually saved the world from an asteroid.
[Chris] over at the New Hobbyist sent in his latest creation, a wireless light switch hidden within a statue bust. While shopping around for another project, he came across a wireless relay that can can be used to switch a standard 120v AC load. He bought the part without a project in mind, but inspiration quickly struck. Some of you young’uns might not remember the original Batman television series, but [Chris] certainly does. To access the Bat Cave, Bruce Wayne had to flip a secret switch located inside a bust of William Shakespeare that adorned his desk. While he doesn’t have a secret door to activate, [Chris] couldn’t think of any better way to switch on the lights in his man cave. He found a similar-looking bust of Beethoven and got to chopping his head off.
He fabricated a small mount for a push button, hiding the battery powered remote underneath, and an old 12v wall wart was repurposed to drive the wireless receiver. While not overly complicated, this is definitely a fun project and could make for a neat light switch in a kid’s room. Interested in some more Batman inspired hacks? Be sure to check out this Bat Cave-style entrance switch from a few years back.
Keep reading to see a video of his hidden light switch in action.
Continue reading “Batman Inspired Hidden Light Switch”
[Matt Meerian] introduced us to his kludge of cardboard, tape, mirrors, and electronics in the form of a clever non lethal robin trap. Whenever a pesky robin would enter the box, a sensor is triggered, the solenoid drops a lid, and the bird is contained (and we assume taken far away after that).
Of course the plan backfired; we wont spoil what happened, but you can click the link above to find out.
Related: Arduino Mouse Trap