Pulse Oximeter from LM324, LED, and Photodiode

pulse-oximeter

This pulse oximeter is so simple and cheap to build it’s almost criminal. The most obvious way to monitor the output of the sensor is to use an oscilloscope. The poor-man’s stand-in for that is a sound card, which is what [Scott Harden] demonstrates in his write-up.

It uses a concept we’ve seen a few times before. The light … Read the rest

Nebulophone microcontroller synthesizer project sounds great

Judging from the video (found after the break) the Nebulophone is one of the best sounding DIY synthesizers we’ve seen. Especially when you consider the simplicity of the hardware design. It uses an AVR chip and an OpAmp. The rest of the parts are just a few handfuls of inexpensive components.

The device was developed by Bleep Labs, and they Read the rest

Making your anime papercraft move to the music

This anime character is dancing to the music thanks to some animatronic tricks which [Scott Harden] put together. She dances perfectly, exhibiting different arm and head movements at just the right time. The secret to the synchronization is actually in the right channel of the audio being played.

The character in question is from an Internet meme called the Leekspin … Read the rest

Scratch-built RFID reader

We never bought an RFID reader because it seems too simple to be all that much fun. But [Abdullah] really caught our eye with his latest project. It’s an RFID reader built from discrete parts, and that’s an adventure we can get behind!

His write-up dives right into the theory of the device. He wrapped his own coil, which … Read the rest

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 … Read the rest

Morse Code interpreter

[Sulaiman Habsi] and two classmates put together a Morse Code interpreter as a class project at Sultan Qaboos University. The system listens to a morse code signal using a microphone, then translates that input to text which is displayed on this character LCD.

The breadboarded circuit feeds an audio signal from the microphone, through an OpAmp, to the ADC of … Read the rest

A Bright Idea

[Jeri Ellsworth] had a bright idea – a brain-activated light bulb that floats above your head. While out and about, she saw some guy with a video game icon attached to metal rod sticking out of his backpack. The rod made the icon appear to be floating above his head (think The Sims), which was the inspiration for this … Read the rest