Cell Phone Signal Detector Schematic!

Posted by on Sep 12, 2013 in Blog, Etc | No Comments

I get so much email about this circuit that I’m going to post it here as jpg.  Here are the files, schematic and PCB, in Kicad. If you use these files, please turn the silkscreen layer on because I didn’t and so my boards didn’t have any. Also, please credit me for the design work. […]

What I’m working on right now 9/9..Maker Faire

Posted by on Sep 9, 2013 in Blog, Etc | No Comments


Open Hardware Summit!

Posted by on Sep 5, 2013 in Blog, Etc | No Comments

I am going to the Open Hardware Summmit tomorrow! It has been held in New York City in the past, and always around the same time as Maker Faire NYC. The location and my addiction to Maker Faire made it really easy for me to attend the past 2 years. This year, the Open Hardware […]

Hacking a Digital Scale

Posted by on Aug 6, 2013 in Blog, Etc | One Comment

My brother Lex works in a lab with a lot of mice. Some of the people who work there have a job weighing mice. The mice need to get weighed everyday, I guess their weight is one way to tell the scientists if they are healthy or not. There are many, many mice in labs […]

DIY EDM Machine

Posted by on Jun 2, 2013 in Blog, Etc | 2 Comments

My husband Ollie decided to build an Electric discharge machining (EDM) machine a couple of months ago. EDM machining is a process where a shape is obtained from a piece of metal by using sparks to remove material! If you have a shape that you wish to reproduce-you make a copper positive of the shape […]


Posted by on Jan 21, 2013 in Blog, Etc | One Comment

I’m working on a new art-engineering project with my brother Lex. It’s a Secret Project so I won’t say too much. The project has to do with fish, and making the fish do our bidding. Jump through hoops fish, jump! The first fish, Goldie, died just a few days after she came home. She wasn’t […]

Oscilloscopes -Part 1

Posted by on Nov 11, 2012 in Blog, Etc | 2 Comments

Hello- It’s been nearly 3 months since I last posted (bad, distracted, Sophi), and I went back and forth about whether or not to post about my new Art project (hint: it involves temperature control and major logistics) or Engineering. I’ve decided to write about one of my most useful lab tools, the oscilloscope. An […]

The Super Green Dot Project

Posted by on Aug 23, 2012 in Blog, Etc | One Comment

Hello! Update: I’ve started a new website, which is keeping me very busy. It’s a website about working for yourself, with interviews with people who have left their “Job” or “Career” and are happy doing what they do now. It’s called The Super Green Dot Project and I hope that you’ll check it out! ~Sophi

Cell Phone Signal Detector – Part 7, transmission line width… and KiCAD!

Posted by on Jul 7, 2012 in Blog, Etc | 3 Comments

I made a couple of PCB versions of a cell phone signal detector and my board layout didn’t work as well as my evaluation board. Thanks to Daryl Mitchell for the photo For a long time, I thought it was because I was home-reflowing the QFN chip. Recently, I had the opportunity to talk to […]

A personal post + blogging at Engineer Blogs

Posted by on Jun 24, 2012 in Blog, Etc | One Comment

Hello! I’ve been writing over at Engineer Blogs since February 2012. I’ve written 7 posts so far. As I blog at EB more, my plan is to focus more on writing about Making Time For Projects and Creating Freedom-based Income 🙂 Thanks to Jeannie for the photo My thoughts and ideas on this are many, […]

Mouse Nose Poke! An IR Beam-Break circuit

Posted by on Jun 2, 2012 in Blog, Etc | 3 Comments

Scientific research mice are often trained behaviorally by giving them treats as rewards. Some Neuroscience students that I met recently train their mice by giving the treat when they poke their noses into an area of the enclosure they are running around in. The area contains an IR emitter and receiver. When the mouse pokes […]

Texting Trapper at Maker Faire 2012

Posted by on May 23, 2012 in Blog, Etc | 2 Comments

This year, Ollie Tanner and I brought the Texting Trapper project to the Bay Area Maker Faire. Update: This project was in the MAKE: Blog … Hooray! I’m also in a Maker Faire after party video (around 8:13) from Dangerous Prototypes The Texting Trapper is a product that detects when people are texting. It is […]

The Texting Trapper

Posted by on May 16, 2012 in Blog, Etc | No Comments

Oliver Tanner and I are exhibiting the Texting Trapper at Maker Faire Bay Area this upcoming weekend. The Texting Trapper is a large scale exhibit which detects the strength of your cell phone. Oliver designed and fabricated the 8 foot tall VU meter. It’s made from 8′ tall aluminum, which he welded into custom extrusions […]

PCBs Needed NOW. Etch!

Posted by on Apr 28, 2012 in Blog, Etc | 5 Comments

I needed a board layout NOW. While I love Laen’s PCB service, I can’t wait 2-3 weeks for boards. I’d never etched boards before, but I’m always up for a challenge! I based my procedure on a bunch of email with my friend Jon and this Hackaday post, which I started reading at 9am. I […]

Giant LED Bar Graph, Maker Faire project 2012

Posted by on Apr 8, 2012 in Blog, Etc | No Comments

I’m building a giant bar graph for the Maker Faire in San Mateo, California. If you’re there, you’ll be able to use it to show your cell phone power level when you’re texting, calling, or going online. I’m definitely nervous about how this is going to work with so many phones in the area and […]

Ollie and Sophi visit Switzerland!

Posted by on Apr 1, 2012 in Blog, Etc | No Comments

UPDATE: I have been officially accepted to Maker Faire Bay Area! I will be exhibiting the Texting Trapper, which is the cell phone signal detection circuit I’ve been blogging about. SOOOO excited! The posts will return to all things geek early April. I’m traveling in Switzerland with my husband and partner Ollie. We’re visiting his […]

Cell phone signal detection part 6

Posted by on Mar 18, 2012 in Blog, Etc | 4 Comments

For the purposes of my project I am defining cell phone signal detection as a change in power level sensed at the frequency of the cell phone. I am not doing any decoding of signals and there is no jamming (although I fully support projects of this type), I am only detecting a very small […]

Cell phone signal detection part 5 – learning from RF Rockstars

Posted by on Mar 16, 2012 in Blog, Etc | 3 Comments

This is a placeholder post, I am going to add to this brief post (graphs! math! antennas!) in the next day or so. So check back! I did want to report that I got a small mention in MAKE blog which was SUPER COOL. Last week, I visited GigaHertz LLC in Pittsburgh. They have been […]

Cell phone signal detection part 4

Posted by on Mar 1, 2012 in Blog, Etc | 2 Comments

20 days until Spring! This has been the suckiest winter ever for snowboarding, I haven’t gone even once. It snowed today and I just didn’t feel like it. Instead I’ve been procrastinating with a Mindbands brainwave detector. Last week I re-spun my cell phone signal detector board in two different versions, both to include smaller […]

Soldering Surface Mount – QFN adventures

Posted by on Feb 12, 2012 in Blog, Etc | 2 Comments

I recently designed my first RF signal detector circuit and PCB layout. There’s all kinds of RF layout warnings out there. “It won’t work if you lay out your board wrong” “You’ll have to troubleshoot invisible wireless signals with no spectrum analyzer.” “How are you going to solder that itty bitty QFN package crucial to […]

Diode detector circuit for radio frequency signal detection

Posted by on Jan 20, 2012 in Blog, Etc | 3 Comments

Update: I am still building circuits that detect a cell phone signal. I’m only detecting that there is a signal, or the fact that there is current present. I’m not detecting what that signal actually means, decoded. That would be illegal. Update: it’s not going to be good as a kit design as the chips […]

Motivational thought for the day

Posted by on Dec 25, 2011 in Blog, Etc | No Comments


Cell phone signal detection part 3

Posted by on Dec 6, 2011 in Blog, Etc | 2 Comments

High frequency signals are so mysterious! How to design PCBs around them, how to detect the signal, how to usefully process… I’ve ordered some building block parts to string together a detection circuit in the 700MHz to 2.8GHz frequency range. I’m starting with an evaluation board from Analog Devices. I decided to go with an […]

Cell phone signal detection part 2

Posted by on Dec 1, 2011 in Blog, Etc | 8 Comments

From some of the emails I’ve gotten, and recent conversations I’ve had, it is clear that many of us are curious about how to characterize, decode or simply identify the level of cell phone signal power/radiation. Wikipedia says typical cell phone transmission power is in the 125mW to 500mW range. I grabbed this picture from […]

Cell phone signal detector part 1

Posted by on Nov 13, 2011 in Blog, Etc | 3 Comments

I’ve been building circuits to detect a cell phone signal. I use Verizon service for my smartphone that runs on the 3G network. 3G by the way, stands for 3rd generation, 1st gen being analog, and the 2nd being PCS. Verizon uses the 800 and 1900MHz frequency band for the 3G network. The basic concept […]

Hello world!

Posted by on Nov 7, 2011 in Blog, Etc | One Comment

Welcome to WordPress. This is your first post. Edit or delete it, then start blogging!

Solar Decathlon, Washington DC

Posted by on Oct 9, 2011 in Blog, Etc | No Comments

It’s been a busy few weeks. Lots of traveling, Finowfurt, Black Rock City, New York City and last week to Washington, DC for the Solar Decathlon. The Solar Decathlon is an exhibition where 20 student teams compete in 9 categories centered around energy efficiency. I had been wanting to go to the Decathlon for the […]

Signals and Systems, a Formulaic Design Approach to creating an Interactive Art piece

Posted by on Sep 19, 2011 in Blog, Etc | One Comment

Since my last post, I have been to Burning Man, the Open Hardware Summit and World Maker Faire NYC.  All of those recent events were AWESOME and have been documented hugely online. However, this post is about Getting Started in creating an electronic or interactive piece. Daniel Rozin’s Wooden mirrors are my absolute favorite interactive […]

Grand Rapids Art Prize

Posted by on Sep 9, 2011 in Blog, Etc | No Comments

From Ran Ortner, winner of the Grand Rapids Art Prize 2009. “… if I ever encounter a young artist who has any doubts about investing the next ten years of his or her life in his or her work, my advice is always to quit. If you have any capacity to quit whatsoever, most certainly […]

Chaos Communication Camp recap

Posted by on Aug 21, 2011 in Blog, Etc | No Comments

Last week I visited Finowfurt near Berlin, Germany, Europe, Earth, Milky Way, Universe for the Chaos Communication Camp conference. The conference was billed as a conference for Hackers and Associated Life Forms. This photo, taken by Jake Blau, is of a rocket sculpture in the center. The talks included everything from DIY solar to e-waste […]

Workshop Babble

Posted by on Aug 7, 2011 in Blog, Etc | No Comments

Every Maker or Engineer needs some kind of workshop to create in. In 1994 I rented a barn on the property of a friend’s rental in Olympia, WA. The barn was awesome, with a high ceiling and huge doors that opened up to the outside. In October, when we arrived, it was warm outside. In […]

Shutter Glass Dress

Posted by on Aug 2, 2011 in Blog, Etc | One Comment

Shutter glass goes opaque when current is applied, and clear when there is none. I grabbed the following gif from Liquid Crystal Technologies. I had the cost of 100 1″ x 3″ pieces estimated and it was in the $4,000 range. Sigh. Since this material is essentially glass, the material is fairly stiff, even in […]

Microprocessor-driven relay

Posted by on Jul 16, 2011 in Blog, Etc | No Comments

Problem: I have a 12VDC fan that needs to be switched on and off. It’s a pretty windy fan with an Endless Breeze label on it, claims to be 900CFM and uses 36Watts. Problem: I’m using a microprocessor (PIC16F877A if you must know) to switch the fan on and off. The fan needs about 3A […]

Theo Jansen’s Strandbeest

Posted by on Jul 14, 2011 in Blog, Etc | No Comments

This…you have got to see. .

Kickstarter = inventor funding

Posted by on Jul 9, 2011 in Blog, Etc | No Comments

Kickstarter is a micro-investing website where you can post a project and ask the online world (and your friends and family) for funding. The project you post has to be a “doing” project. Kickstarter doesn’t accept “fund my life” fundraisers. Some of the projects asking for funding are Product Design projects. This is great because […]

Pianococktail – a piano that plays drinks!

Posted by on Jul 3, 2011 in Blog, Etc | No Comments

I have only seen the Pianococktail once, at an ITP student show (2008) at NYU, in New York City. It is a piano whose keys actuate solenoids that open valves to bottles containing drink mixtures, Red Bull, alcohol and soda. Whatever song you play will mix its own special drink. I’ve always thought this was […]

A Watt is not a Watt, What?

Posted by on Jun 24, 2011 in Blog, Etc | No Comments

I’ve just started to work with sound for the first time. Oh, I’ve dabbled a little bit in the record-able birthday card arena, built a couple of embedded amplifiers and a filter (strong word for a capacitor) or two, but I’m pretty clueless when it comes to the sound lingo. The HeartBeat Dome project requires […]

HeartBeat Dome and the path to creativity

Posted by on Jun 19, 2011 in Blog, Etc | No Comments

It’s time for a new project again. The new project will be designed for Burning man Festival in Black Rock City, Nevada. I’m working with three other people on this one, and it’s working out really well. Two of the people live 3,000 miles away from me so designing something over email and texting is […]

Finger Pulse Oximeter!

Posted by on Jun 7, 2011 in Blog, Etc | 3 Comments

Check back for more posts on the Oximeter. Here’s the link for the Maker Faire recap. I ordered a finger pulse oximeter online, which was waiting for me on my porch when I got home yesterday. A pulse oximeter measures a couple of important human body functions- the heart rate and hemoglobin oxygen saturation. Heart […]

Maker Faire Recap

Posted by on May 28, 2011 in Blog, Etc | 2 Comments

This past weekend Ollie and I exhibited at Maker Faire in San Francisco. Many of my favorite organizations were there, Exploratorium, Spark Fun, Digikey, Lego, Etsy, Instructables, Google, NASA (!!!)…. and many smaller individuals who haven’t yet grown into largeish organizations, MaceTech, Ira Sherman (chastity belts!!!), Sensebridge, Mark Lottor. Setup was very easy- we shipped […]

555 timer lighting controls and a wee bit of silicone casting

Posted by on May 13, 2011 in Blog, Etc | No Comments

I am not so confident about my newest project. For one thing, it encompasses a number of unrelated processes, all of which have a failure factor. Mold making, casting, laser cutting, tube bending and of course circuit design. The concept is that there is a stepped white acrylic base, with stainless steel tubing coming out […]

CLEO conference – lasers are cool

Posted by on May 10, 2011 in Blog, Etc | No Comments

Last week I worked at the CLEO conference in Baltimore, Maryland. It was a fun week- it was nice and sunny, I got a stylee ride both ways (one way in Diesel Jetta & the other in Nissan Hybrid) and ate some really good seafood. The CLEO conference is a trade show and conference about […]

Analog lighting control and the LED

Posted by on May 7, 2011 in Blog, Etc | One Comment

Do you have dimmer switches on your incandescent lights? They used to be basically a resistor that controls the current going to the filament in your bulb. The filament is the little coiled wire inside of the bulb. As current is put into the filament, it is released as heat. When a wire gets really […]

Bull and Buddha, Poughkeepsie, NY

Posted by on Apr 28, 2011 in Blog, Etc | No Comments

I decided to meet a friend tonight at Bull and Buddha in Poughkeepsie, NY. Look at these gorgeous lamps! YUMMY Menu!! And I love the Big Buddha behind the bar.

Disco Smart Car

Posted by on Apr 27, 2011 in Blog, Etc | No Comments

Hell yeah!

Maker Faire – new project!

Posted by on Apr 24, 2011 in Blog, Etc | No Comments

I just found out that I am exhibiting at the Bay Area Maker Faire! I applied after the deadline and was accepted as a last-minute entry. So I will make something new to show and also bring a couple of 2010 pieces. The new thing that I am conceptualizing has something to do with software-less […]

Felt sperm! (I’m sooooo mature)

Posted by on Apr 19, 2011 in Blog, Etc | One Comment

Hine Mizushima does some great original work…and this one cracked me up.

Keepon robot helps autistic children

Posted by on Apr 14, 2011 in Blog, Etc | No Comments

I just saw this video of Keepon, a robot designed to help autistic children engage socially. It looks like an old style push button toy, but has 2 cameras (!!) in its head and a microphone in its nose. Awesome bonus: this video (@ 1:25) briefly shows off the mechanics that make Keepon interact. The […]

It’s all about the Make-cation

Posted by on Apr 11, 2011 in Blog, Etc | No Comments

My new friend Stephanie Alarcon coined the word Make-cation earlier today. Check out her blog, it rocks! The Make-cation is the vacation that you take from your regular life in order to make stuff! Making stuff can take a long time…. from thinking it up, to researching it, to screwing it up, to redoing it, […]

Oscillating with the 74HC14

Posted by on Apr 9, 2011 in Blog, Etc | 7 Comments

Today, I built an oscillator with the 74HC14 hex inverter Schmitt trigger. Here’s the datasheet. I thought this was interesting, the inventor of the Schmitt trigger, Otto Herbert Schmitt (1913 – 1998), was a scientist who worked both in physics and biology. He figured out the trigger while studying neural impulse propagation in squid nerves. […]

Open Source Hardware logo selected!

Posted by on Apr 8, 2011 in Blog, Etc | No Comments

Yesterday, the open source hardware logo designed by Macklin Chaffee was selected. Over 9000 people voted! From the OSHW definition, the principle is “Open source hardware is hardware whose design is made publicly available so that anyone can study, modify, distribute, make, and sell the design or hardware based on that design.” Yessssssss! Collaboration rocks […]

Recycling the Metrocard

Posted by on Apr 6, 2011 in Blog, Etc | No Comments

Stephen Shaheen designed this bench made from Metrocards on a steel frame. Mr. Shaheen, I salute your imagination!

The Folding Plug

Posted by on Apr 1, 2011 in Blog, Etc | One Comment

I ran across this super cool design today while looking at power strips. The folding plug from the UK based Made in M!nd folds to be 0.393″ thin! It will be released sometime this year with a product line designed around it … maybe some folding phone chargers?

Back to basics…the 74HC04

Posted by on Mar 27, 2011 in Blog, Etc | 4 Comments

I love blinky things and I love to think about how to design something a little differently. Probably the most common way to control red-green-blue LEDs is with a pulse width modulation signal from a microcontroller. Many coding interfaces have built in PWM functions so that you can be up and running within a few […]

Voltage and Current RMS rambling

Posted by on Mar 16, 2011 in Blog, Etc | No Comments

An easy way to calculate the power needed to drive the speaker uses Paverage = VRMS * IRMS, or Paverage = Power (Watts) = Voltage squared/ Resistance (Ohms). This uses only the resistive part of the impedance. Watts RMS actually doesn’t exist. The voltage in the formula refers to RMS Voltage (explained below), but the […]

Loudspeaker ramblings

Posted by on Mar 15, 2011 in Blog, Etc | No Comments

I’ve never really thought too much about getting sound out into the world. Everything just…works. I have an old Samsung mp3 player, it plays music through speakers into my ear. I can adjust the volume easily. Same for my beloved Droid phone. It outputs both music and voices. Last summer I built something that ran […]