Chiptune player uses preprocessed .MOD files

[Kayvon] just finished building this chiptune player based on a PIC microcontroller. The hardware really couldn’t be any simpler. He chose to use a PIC18F2685 just because it’s big enough to store the music files directly and it let him get away with not using an external EEPROM for that purpose. The output pins feed a Digital to Analog Convert (DAC) chip, which in turn outputs analog audio to an LM386 OpAmp. The white trimpot sandwiched between the chips controls the volume.

The real work on this project went into coding a program which translates .MOD files into something the PIC will be able to play. Because of the memory limits of the chip it is unable to directly use all of the instrument samples from these files. [Kayvon] wrote a program with a nice GUI that lets him load in his music and page through each instrument to fine-tune how they are being re-encoded. The audio track from the video after the break doesn’t do the project justice, but you will get a nice look at the hardware and software.

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Fill in the bass on your PSP

[Michael Chen] felt the sound his PSP was putting out needed more dimension. Some would have grabbed themselves a nice set of headphones, but he grabbed his soldering iron instead and found some space where he could add a bigger speaker.

Mobile devices tend to cram as much into the small form factor as possible so we’re surprised he managed make room. But apparently if you cut away a bit from the inside of the case there is space beneath the memory card. [Michael] cautions that you need to choose a speaker rated for 8 ohms or greater  in order to use it as a drop-in replacement for one of the two original speakers. But he also touches on a method to use both stock speakers as well as the new one. He suggests grabbing an LM386 op-amp and a capacitor and hooking them up. Yep, there’s room for that too if you mount it dead-bug-style. We wonder how the battery life will be affected by this hack?

Adding sound and light to your radio controlled vehicles

[Nicholas] wanted to add some flair to his RC car. In addition to the headlights that you see above, there’s brake lights, and a horn that plays “Dixie” like the General Lee in the Dukes of Hazard. All of this is triggered by the wireless controller, but he figured out a way to monitor the servo signals in order to add the additional features.

The hack is driven by a Propeller chip. [Nicholas] patches into the servo lines by adding a servo-in and servo-out header to his prototyping shield. With that in place he’s able to tap into the voltage and ground pins to power the microcontroller. By attaching a 4k7 resistor to the control line, he can listen in on the servo signals using the Propeller.

This RC car has a throttle servo. So when the throttle is opened all the way up the Propeller chip flashes some white LEDs in the headlights, and uses an LM386 audio amplifier to play a tune. When the throttle is pulled all the way back the brake lights are activated. Don’t miss the test footage of this which is embedded after the break.

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Speaker-mounted WAV player for street performances

This naked speaker is the basis for [MaoMakMaa’s] newest project called the Wavedrone. He plans on using the autonomous and cable-less device during street performances. You can hear the effect of some stretched jazz cords being played on it in the video clip after the break. The sound is kind of an ethereal background noise that observers might not immediately realize is there.

You can see the 9V battery which serves as the power source clinging to the frame of the speaker. A 7805 linear regulator tames that battery and feeds the two IC’s on the circuit board seen to the right. The ATtiny85 is reading music from an SD card and playing it back in mono (obviously) with the help of an LM386 audio amplifier chip. The trimpots that go into the high pass and low pass filters in between the microcontroller and amplifier allow for a bit of sound manipulation, but we’re more impressed with the quality of the sound this is getting when properly trimmed.

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This GLaDOS potato is a lie

Why settle for virtual reality when you can make the digital world into reality? [Josh] wanted to have a GLaDOS potato accompany him through life when not playing Portal 2. He set to work to see what kind of replica prop he could come up with. Judging from the image above, and demo video after the break, he nailed it right in the spud.

There’s no worrying about rot. The potato and a few parts were molded from Sculpey and baked in the oven. Since the fake spud is hollow in the center it’s easy to hide the bits that make it talk. An old MP3 player was loaded with quotes from the game, and plays them back via an LM386 audio amplifier circuit and a speaker hidden below the electronic eye. The eye is lit by five yellow LEDs which are also tied into the amplifier to make them blink and fade with the intensity of the audio signal.

A paint job and the nails and wire really make the build look just right. Now [Josh] needs to host a geek-themed Halloween party so he can really show this off.

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LM386 Altoids tin amp


Hacker [Dino Segovis] is back again with the fifth installment in his “Hack a Week” series. This time around he has put together a 1/2 watt audio amplifier that would make for a great weekend project. He’s a big fan of the LM386 amplifier chip because it does so much in such a small package. Since it is so versatile, he used it as the centerpiece of his Altoids tin amplifier.

Now an audio amp inside an Altoids tin isn’t exactly a new concept, but [Dino] takes the time to discuss the circuit in detail, which is great for any beginners out there who are looking for a fun and relatively easy project. After a high-speed video of the assembly process he walks us through the completed amp, then treats us to a couple of short demos.

One thing that makes his amp different than others we have seen in the past is the addition of a 1/4” guitar jack, which allows him to use his amplifier as a combo amp/distortion effect box.

It’s another job well done, so be sure to keep reading if you’d like to watch the latest Hack a Week episode in its entirety.

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Pitch shifter makes your band sing higher

[Markus Gritsch] tipped us off about this little module he built to shift the pitch of audio playback. It uses a PIC 24FJ along with a couple of LM386 amplifier chips to manage the input and output signals. At the push of a button, audio being fed through the device can be modulated to a different key without changing the playback rate. Here it’s being used with a iPod but because this device just sits between an audio source and a signal input we wonder if you can have some fun on the cellphone with this circuit?

Check out the video after the break to hear it in action. We must compliment [Markus] on his layout. We haven’t seen the underside of that protoboard but he’s done a great job of fitting everything into a small area. You can find the schematic for the circuit by following the link at the top of this feature. He took a picture of his hand-drawn plans which saves him time from laying it out with something like KiCAD but still gives us the details that we love to see with your projects.

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