The Retro Shield, an Arduino Proto Shield for making many different circuits.

Retro Shield Replaces Springs With Jumpers, Includes Blinkenlights!

Is it an AM radio? Yes. It is a 555 LED flashing circuit? Yep. How about a hex counter with a 7 segment display? That too. Five different colored LED’s to satisfy your need for blinkenlights? Even that! What is this magical contraption? Is it one of those old school 30-in-1 or 50-in-1 “Science Fair” kits with the jumper wires and the springs? Almost!

When [grandalf]’s friend showed them a project where a 555 timer was installed on an Arduino shield, they realized two things: This whole “could have done that with a 555 timer” meme is a lot of fun, and “I’ve got an old 556 chip, I wonder if I can build one?” The answer is yes, and so much more.

Starting with the 556 timer, and inspired by the old spring-and-jumper kits of the past, [grandalf]’s “556 on a Proto Shield” project evolved into a creation they call the Retro Shield. Snowballing like so many hacker projects, it now includes several built in circuits and components. Breadboard jumpers are used to connect components through strategically placed pin headers, of which there are quite a few!

To make it all fit, some parts were substituted with more compact pieces such as an LM386 instead of an LM380.  The AM radio portion is supplied by an all-in-one radio chip, the ZN414. With the scope creep picking up steam, [grandalf] eventually added so called sidecars- bits of board that contain controls and a speaker hanging off the side of the Proto Shield.

It is not mentioned if the Retro Shield integrates with the Arduino or not. All the same, the Retro Shield has been used to pick up local AM stations, blink LED’s and amplify audio with the LM386. Like [grandalf] we’re sure that the Retro Shield can be used for much more. We hope that [grandalf] expands on the concept and inspires future hackers to answer the question “I wonder what happens if I try this.” 

If you haven’t set eyes on one of the all-in-one kits, check out this 200-in-1 kit teardown and review. And of course, if you have your own hacked up projects to share, be sure to let us know through the Tip Line!

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”

[Fran] Is Helping Santa Slay This Year

We know at least one person who ought to make Santa’s ‘nice’ list this year. [Fran] was probably near the top of it already, but sending Santa a handmade greeting card with a fully-functioning guitar amp inside will probably make him rewrite her name in glitter, or silver Sharpie.

This stocking stuffer-sized amp is based around the LM386 and the bare minimum components necessary to make it rock. Everything is dead-bug soldered and sandwiched between two pieces of card stock. The first version with a single 386 sounded okay, but [Fran] wanted it louder, so she added another stage with a second 386. [Fran] glued the rim of the speaker directly to the card so it can act like a cone and give a better sound than the speaker does by itself.

All Santa needs to rock out is his axe and a small interface made of a 1/4″ jack and a 9 V wired to a 3-pin header that plugs into the card. He can take a break from Christmas music and let some of those cookies digest while he jams. Be sure to check out the build video after the break if you want to stay off the ‘naughty’ list.

Want to make your own musical greeting card? If you can program an ATtiny85, you won’t need much more than that to send a smile. If visual art is more your thing, 3D print them a 2D picture.

Continue reading “[Fran] Is Helping Santa Slay This Year”

It’s A TV-Scope-Guitar Amplifier!

Guitar amplifiers are a frequent project, and despite being little more than a simple audio amplifier on paper, they conceal a surprising quantity of variables in search of a particular sound. We’ve seen a lot of them, but never one quite like [Nate Croson]’s CRT TV guitar amplifier. The LM386 doesn’t just drive the speaker, he’s also using it to turn the TV into a crude oscilloscope to form a visualisation of the sound.

The video showing this feat is below the break, and it puts us in a quandary due to being short on technical information. He’s driving the horizontal coils with the TV’s 50 Hz sawtooth field timebase, and the vertical ones with the audio from the LM386. We aren’t sure whether he’s rotated the yoke or whether the connections have been swapped, but the result is certainly impressive.

So given that there’s not quite as much technical detail as we’d like, why has this project captured our interest? Because it serves as a reminder that a CRT TV is a bit more than a useless anachronism, it’s a complex analogue device with significant and unique hacking potential. The older ones in particular provide endless possibilities for modification and circuit bending, and make for a fascinating analogue playground at a very agreeable price. It’s worth pointing out however that some of the voltages involved can make them a hazardous prospect for the unwary hacker. If you’re interested though, take a look at our dive into an older model.

Continue reading “It’s A TV-Scope-Guitar Amplifier!”

Does This Timber Have The Right Timbre?

A hi-fi amplifier used to be a rite of passage for the home electronic constructor, back in the days when consumer electronics was still dominated by analogue entertainment. It’s unusual then to see [carbono.silício]’s stereo amplifier project, constructed in an open-wire circuit sculpture form on a log. You didn’t read that incorrectly, it’s built not on a breadboard but on a piece of Olea Maderensis, or Madiera Olive wood, complete with bark. This endangered tree was not felled, instead it was a piece blown down after a storm.

The circuit is slightly unusual for a project such as this, in that it uses a pair of LM386 audio amplifier chips. This isn’t an unusual component, but it’s one more commonly seen providing the amplification for a small speaker project than in a stereo hi-fi amplifier. But the construction is beautifully done, with very neatly routed wires, a single central volume knob, and a blue LED power light. A particularly nice touch are the aluminium electrolytic capacitors, we suspect having had their plastic sleeving removed.

We’ve had our share of stereo amp projects here, and some of them are surprisingly simple. We have even been known to partake of them ourselves.

State Of The Art Big Mouth Alexa Bass

Hackers seem intent on making sure the world doesn’t forget that, for a brief shining moment, everyone thought Big Mouth Billy Bass was a pretty neat idea. Every so often we see a project that takes this classic piece of home decor and manages to shoehorn in some new features or capabilities, and with the rise of voice controlled home automation products from the likes of Amazon and Google, they’ve found a new ingredient du jour when preparing stuffed bass.

[Ben Eagan] has recently completed his entry into the Pantheon of animatronic fish projects, and while we’ll stop short of saying the world needed another Alexa-enabled fish on the wall, we’ve got to admit that he’s done a slick job of it. Rather than trying to convince Billy’s original electronics to play nice with others, he decided to just rip it all out and start from scratch. The end result is arguably one of the most capable Billy Bass updates we’ve come across, if you’re willing to consider flapping around on the wall an actual capability in the first place.

The build process is well detailed in the write-up, and [Ben] provides many pictures so the reader can easily follow along with the modification. The short version of the story is that he cuts out the original control board and wires the three motors up to an Arduino Motor Driver Shield, and when combined with the appropriate code, this gives him full control over Billy’s mouth and body movements. This saved him the trouble of figuring out how to interface with the original electronics, which is probably for the better since they looked rather crusty anyway.

From there, he just needed to give the fish something to get excited about. [Ben] decided to connect the 3.5 mm audio jack of an second generation Echo Dot to one of the analog pins of the Arduino, and wrote some code that can tell him if Amazon’s illuminated hockey puck is currently yammering on about something or not. He even added a LM386 audio amplifier module in there to help drive Billy’s original speaker, since that will now be the audio output of the Dot.

A decade ago we saw Billy reading out Tweets, and last year we presented a different take on adding an Alexa “brain” to everyone’s favorite battery powered fish. What will Billy be up to in 2029? We’re almost too scared to think about it. Continue reading “State Of The Art Big Mouth Alexa Bass”

A Guide To Audio Amps For Radio Builders

For hams who build their own radios, mastering the black art of radio frequency electronics is a necessary first step to getting on the air. But if voice transmissions are a goal, some level of mastery of the audio frequency side of the equation is needed as well. If your signal is clipped and distorted, the ham on the other side will have trouble hearing you, and if your receive audio is poor, good luck digging a weak signal out of the weeds.

Hams often give short shrift to the audio in their homebrew transceivers, and [Vasily Ivanenko] wants to change that with this comprehensive guide to audio amplifiers for the ham. He knows whereof he speaks; one of his other hobbies is jazz guitar and amplifiers, and it really shows in the variety of amps he discusses and the theory behind them. He describes a number of amps that perform well and are easy to build. Most of them are based on discrete transistors — many, many transistors — but he does provide some op amp designs and even a design for the venerable LM386, which he generally decries as the easy way out unless it’s optimized. He also goes into a great deal of detail on building AF oscillators and good filters with low harmonics for testing amps. We especially like the tip about using the FFT function of an oscilloscope and a signal generator to estimate total harmonic distortion.

The whole article is really worth a read, and applying some of these tips will help everyone do a better job designing audio amps, not just the hams. And if building amps from discrete transistors has you baffled, start with the basics: [Jenny]’s excellent Biasing That Transistor series.

[via Dangerous Prototypes]