Hack Together Your Own Bat Signal

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”

3D Printed DIY Neuralyzer

We agree with you. We can never have enough cosplay hacks. And the ones that include some electronics element definitely have a special place in our hearts. That’s why when we ran across [Maddogg0’s] 3D printed Neuralyzer on Instructables, we knew we had to share.

You may recall [How to make’s] DIY Neuralyzer that we featured a few weeks ago which required more of a metal-working approach. [Maddogg0’s] design might be a bit more convenient for those of you that have a 3D printer, but no machine shop.

We love the elegant simplicity of [Maddogg0’s] design. The entire enclosure is printed in two halves that are held together by magnets. One half of the enclosure houses a single coin cell battery and a tiny circuit board for holding the LEDs in place, really giving the Neuralyzer some shine. In true maker fashion, [Maddogg0] released the necessary design files on TinkerCAD so anyone can reuse, remix, and reshare.

Whichever design you fancy, [Maddogg0’s] or [How to make’s], be careful not to point the Neuralyzer at yourself and always remember to wear your sunglasses!

 

 

PCB Jewelry Never Looked So Good

[Gautchh] wanted to make something nice for his girlfriend. Being the DIY enthusiast he is, he thought a hand-made gift would resonate with her better than something he could pick up from the store. Enter NeckLight, a glow in the dark PCB necklace. He was first inspired by another project he ran across on Instructables, then decided to put his own little spin on the design. It’s cool how that works. Interestingly enough, it was his first time using Fusion 360, but you probably wouldn’t know that if you took a look at the results.

Aside from soldering, the trickiest part of this project was trying to get the LED intensities just right. [Gautchh] found the best way to do this was experimentally by testing each LED color with a series of resistors. He wanted to ensure he could get the color intensity and the LED current just right. Finally, with a touch of acetone, he was done (though he might want to try some alternatives to acetone next time).

[Gautchh] also thinks that this project would be a really nice way for beginners to learn surface mount (SMD) soldering. We’ve seen a few cool SMD LED projects before. Who could forget those competitive soldering challenges over at DEF CON?

Anyway. Thanks, [Gautchh]. We hope your girlfriend, and your dog, enjoyed their gifts.

Tips From A Former Niche Item Etsy Store

Etsy is a service aimed at providing a way for makers of handmade items to sell them online. [Bithead] closed up shop earlier this year and wrote up an interesting perspective on what did and didn’t work out. The main market for [Bithead]’s store was Star Wars cosplayers, because it all started with some Star Wars inspired com pads, some of which are pictured here.

One thing [Bithead] felt worked well overall was to “think big, start small, and scale fast.” In essence, bootstrap things by selling inventory on hand and carefully monitoring demand, then if demand is sustained, ramp up to larger batches, which are more efficient. The risk of making larger part orders and carrying more stock on hand is offset by the reliable demand. Waiting until solid data on reliable demand is available means missing out on early sales, but it’s a low risk approach that works well for niche products that have little or no real competition.

A couple things that didn’t work out were efforts to follow Etsy’s advice to add more products to attract a wider audience, and to try out tools for offering discounts and incentives aimed at turning abandoned carts into sales. Neither went well. The first resulted in adding items that sold poorly, diluted the focus of the store, and incurred a cost for each listing. The second never seemed to have any impact on sales whatsoever. Perhaps there is a place for these efforts, but [Bithead]’s niche market wasn’t it.

It’s a good read about how things went for an Etsy store that served a niche audience over three years. The perspective and experiences might be useful to anyone looking to turn a bright idea into something sold online, so if you’re at all interested, take a few minutes to check it out.

We’ve seen [Bithead]’s work before, this lightsaber-inspired violin bow was one project that went on to become a kit for sale.

Lighting Up Your Spectrespecs

In the ever-popular world of Harry Potter, a pair of Spectrespecs are useful if you’re hunting for wrackspurts and nargles. While we’ve never spotted either of these creatures ourselves, if you’d like to go out on a hunt, [Laveréna]’s build might be for you.

To start with, you’ll need the frames for the Spectrespecs. [Laveréna] elected to source hers commercially, but you can 3D print them or even craft them by hand if you so desire. Then, a TinyLily microcontroller board is installed, with its small size allowing it to be tucked neatly out of sight in the top of the sunglasses. Two NeoPixels are then installed, with the TinyLily programmed to flash the LEDs in the requisite blue and red colors for easy identification of supernatural creatures.

Tools such as cheap microcontrollers designed for wearables and low-cost addressable LEDs are making advanced cosplay designs easier than ever. Whipping up custom blinkables no longer requires knowledge of advanced multiplexing techniques and how to properly drive high-power LEDs. Of course, LED wearables do still get properly advanced – like this skin-based 7-segment display. If you’ve got a glowable project of your own that you’re dying to share, be sure to let us know!

Fast Fresnel Hack Embiggens The Smallest Of Heads

Aside from frightening small children, we have absolutely no idea why anyone would need a face-magnifying headpiece. But the video below gives us a chuckle every time we see it, and we figure a good laugh that incorporates a quick optics hack is worth a look.

When he’s not playing geek in a box, [Curious Marc]’s videos usually have more of a retrocomputing theme, like his recent conversion of a vintage terminal to a character set from a made-up language, or helping to revive an Apollo Guidance Computer. Given gems like those, we were surprised to learn that [Marc]’s background is physics – optics, to be precise – and that he studied at École Polytechnique, the same school famed physicist Augustin-Jean Fresnel attended. Which fits right into this build since it features one of those large, plastic Fresnel lenses. After a fascinating detour into the history of Fresnel’s namesake lens, [Marc] proceeds with the build.

It’s simplicity itself – a box big enough to wear on the head with one end replaced by the Fresnel lens. A strip of LEDs – warm white, please, lest the wearer takes on a deathly pall – lines the edge of the box just behind the lens. If you want to get fancy, maybe attaching a hard-hat suspension piece would make it more wearable, but even as is it’s just a hoot to see someone with a magnified and distorted head walking around. One probably should be careful not to look at the sun while wearing this, however, for reasons that become apparent beginning at the 3:24 mark of the video.

Thanks to [Marc] for perhaps the oddest YouTube face-reveal yet, and for a great idea for a quick cosplay hack.

Continue reading “Fast Fresnel Hack Embiggens The Smallest Of Heads”

Be Anyone Or Anything With Facial Projection Mask

In the market for a low-poly change to your look? Hate the idea of showing up for a costume party only to find out someone is wearing the same mask as you? Then this face changing front-projection mask may be just the thing for you.

To be honest, we’re not sure just how much [Sean Hodgins]’ latest project has to do with cosplay. He seems to be making a subtle commentary about dealing with life in the surveillance state, even though this is probably not a strategy for thwarting facial-recognition cameras. [Ed Note: Or maybe it’s just Halloween?]

The build consists of a Raspberry Pi and a pico projector of the kind we’ve seen before. These are mated together via a custom PCB and live inside a small enclosure that’s attached to the end of a longish boom. The boom attaches to the chin of 3D-printed mask, which in turn is connected to the suspension system of a welding helmet. Powered by a battery pack and controlled by a smartphone app, the projector throws whatever you want onto the mask – videos, effects, even images of other people. Even with some Photoshop tweaks to account for keystone distortion from the low angle of projection, there’s enough distortion that the effect is more artistic than masquerade. But honestly, having your face suddenly burst into flames is pretty cool. We just wonder what visibility is like for the wearer with a bright LED blasting into your eyes.

As a bonus, [Sean] has worked this build into a virtual treasure hunt. Check out 13thkey.com and see what you can make from the minimal clues there.

Continue reading “Be Anyone Or Anything With Facial Projection Mask”