Everything for Electronics
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Build an Inexpensive Magnetometer

This article describes a Hall-effect based magnetometer that uses an inexpensive analog Hall-effect sensor, an Arduino, and LCD. The linearity of the magnetometer is surprisingly good when compared against a commercial magnetometer. This unit can be operated manually or make measurements under computer control, so we’ll use our magnetometer in a computer-controlled setup to measure the BH-curve of small sample of magnetic material.

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The Electric Brains of Yesteryear

In the 1950s and ‘60s, Popular Electronics and other magazines carried ads for strange looking machines called Geniacs and Brainiacs. The ads claimed they were “electric brains” that could play Tic-Tac-Toe and NIM. A while ago, I bought several sets on eBay and I would like to share my experiences of learning about them and my sometimes frustrating — but successful — efforts to get them to work.

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Build an Instant Heart Pulse Sensor

In about 10 minutes and for about $6, you can display the blood flow through your finger. From this measurement, you can extract your heart rate, check for arrhythmia, and even modulate a red light to pulsate with your heart rate. Here’s how.

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Build a Lunch Box Jukebox

The Lunch Box Jukebox is a compilation of various projects to make a compact portable music, video, and game entertainment device with the Raspberry Pi Zero at the heart of the Jukebox Internet radio.

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Build a Freezer Alarm Circuit

I’m not sure if it’s absent mindedness or just old age, but sometimes I’ll forget to close the food freezer lid after shopping for groceries. With food prices seemingly going up every three days, there’s really no good time to lose a pile of food because of a simple mistake. This article describes my solution to the freezer problem.

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Build the FLiPVox Laser Theremin

In my previous Theremin article, I described the first of my laser Theremin projects: the LASERVox. This is a simple-to-construct Theremin-like device that acts as a MIDI controller for a synthesizer. In that article, I discussed the possibility of a more analog style laser Theremin that has its own built-in synthesizer or pitch generator. That’s the topic of this article! We’ll build the FLiPVox: a continuous pitch laser Theremin with its own mini synthesizer.

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How You Can Intercept Secret Messages Being Sent to Spies

Believe it or not, there are powerful radio stations all over the world sending out messages to spies every day, and you can hear them with an inexpensive shortwave radio and a simple antenna. You probably won’t be able to decode them, but it’s a real kick to tune in these clandestine signals.

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