A ‘meter is one of the most important tools on any electronics bench. After you’ve exhausted your five senses trying to figure out what’s happening in a circuit, firing up the old ‘meter is usually the next step. Meters are largely digital nowadays, but their analog ancestors are still widely available. We have a chemist and inventor named [Edward Weston] to thank for the portability and ubiquity of DC measuring equipment.
After immigrating to the United States from England with the degree in medicine his parents wanted him to earn, [Edward Weston] asserted that he was more interested in chemistry. His career began in electroplating, where he soon realized that he needed a reliable, constant current source to do quality plating. This intense interest in power generation led him to develop a saturated cadmium cell, which is known as the Weston cell. Its chemistry produces a voltage stable enough to be used for meter calibration. The Weston cell is also good for making EMF determinations.
Within a few years, he co-founded the Weston Electrical Instrument Corporation. The company produced several types of meters along with transformers and transducers known for their portability and accuracy. In 1920, [Weston & Co.] created this 1920 educational film in cooperation with the United States Navy as part of a series on the principles of electricity.
The viewer is invited to consider the importance of measurement to civilization, most notably those fundamental measurements of length, mass, and time. [Weston] positions his electrical measuring instruments at this level, touting them as the international favorite. We get the full tour of a Weston meter, from the magnet treated for permanence to the specially designed pole pieces that correctly distribute lines of magnetic force. What education film about electromagnetism would be complete without an iron filings demonstration? This one definitely delivers.
Continue reading “Retrotechtacular: Weston Electrical Instruments”
In June of 2014, [Afrdt] spent two weeks on a boat as an artist-in-residence in Linz, Austria. During that time, she created a dress that detects EMF waves and outputs them to vibration motors and a headphone jack.
[Afrdt] started by making two EMF coil antennas and sewed them to cuffs that snap together. She crafted fashionable fabric stripes that both conceal and carry the cables from the coils to an Adafruit FLORA that’s sewn into the body of the dress. The wearer experiences haptic feedback via vibration motors in the chest, and sonic feedback from a mini female headphone jack built into the collar. The zipper functions as a low-pass filter and volume control for the jack. One side bears resistive tape and runs to the FLORA, which is programmed to play an 800Hz tone. The other side runs to the headphone jack via conductive thread. As the zipper is opened, the pitch increases to toward the maximum pitch of 880Hz.
She drew inspiration for this project from [Aaron Alai]’s EMF detector project and built the code on top of it. Broader documentation and many more pictures are available both at [Afrdt]’s site and the residency program’s site.
This project is an official entry to The Hackaday Prize that sadly didn’t make the quarterfinal selection. It’s still a great project, and worthy of a Hackaday post on its own.
[Tuomas Nylund] wanted a way to visualize the electromagnetic fields (EMF) around him. He figured the oscilloscope was the tool best suited for the task, but he needed a way to pick up the fields and feed them into one of the scope’s probes. He ended up building this EFM probe dongle to accomplish the task.
He admits that this isn’t much more than just an inductor connected to the probe and should not be used for serious measurements. But we think he’s selling himself short. It may not be what he considers precision, but the amplification circuit and filtering components he rolled into the device appear to provide very reliable input signals. We also appreciate the use of a BNC connector for easy interface. Check out the demo video after the break to see the EMF coming off of a soldering station controller, from a scanning LCD screen, and that of a switch-mode power supply.
Continue reading “EMF oscilloscope probe”
As a biomedical equipment technician [Adam Outler] equipment needs to be in top working condition. The emergency room staff were complaining about erroneous noise on the electrocardiogram and it’s his job to fix it. He suspected EMF interference so as a quick first step he decided to throw together an EMF detector using an Arduino. It uses a bank of LEDs as an indicator bar to reflect the EMF picked up by the red antenna. In the video after the break [Adam] checks a room for possible sources of interference, treating the recharging circuit from the emergency lights as the most likely culprit. Since the ECG is many times more sensitive to EMF than the Arduino, this turns out to be a quick and easy way to make sure he’s not barking up the wrong tree.
Continue reading “Arduino EMF sensor”
[Aaron] calls this project “Stochasticity”. It uses two sponges as a musical interface. The performer wears a wrist strap and then draws on the table with water from the sponge to play different notes. You really need to watch the video to fully understand what’s going on here.
We’re guessing that this is Arduino based since some of his other projects are as well. You can try out another quick project of his, an Arduino electromagnetic field detector. Check out video of that after the break.
Continue reading “Sponge music”