Have you ever taken a picture indoors and had unsightly black bars interrupt your otherwise gorgeous photo? They are caused by lighting which flickers in and out in its normal operation. Some people can sense it easier than others without a camera. The inconsistent light goes out so briefly that we usually cannot perceive it but run-of-the-mill camera phones scan rows of pixels in sequence, and if there are no photons to detect while some rows are scanned, those black bars are the result. Annoying, right?
What if someone dressed that bug of light up as a feature? Instead of ruining good photos, researchers at the University of California-San Diego and the University of Wisconsin-Madison have found out what different frequencies of flicker will do to a photograph. They have also experimented with cycling through red, green, and blue to give the effect of a poorly dubbed VHS.
There are ways an intelligent photographer could get around the photo-ruining effect with any smartphone. Meanwhile DSLR cameras are already immune and it won’t work in sunlight, so we are not talking about high security image protection. The neat thing is that this should be easy to replicate with some RGB strips and a controller. This exploits the row scanning of new cameras, so some older cameras are immune.
Telephone answering machines were almost a fad. They were hindered for years by not being allowed to connect to the phone lines. Then a mix of cell phones and the phone company offering voicemail made the machines all but obsolete. Unless you are really young, you probably had one at some point though. Some had digital outgoing messages and a tape to record. Some had two tapes. But did you ever have one that didn’t connect to the phone line at all? Remember, there was a time when they couldn’t. My family had one of these growing up and after doing enough research to find it in an old catalog, I decided you might like to know how it really worked.
Even if you grew up in the 1960s and 1970s, it is hard to imagine how little technology there was in an average person’s home at that time. You probably had one TV and one wired telephone. You probably had a radio or two and maybe even a record or tape player. If you were very fancy, you had a big piece of furniture that had a TV, a turntable, a radio, and a tape player in it. No cell phones, no computers, no digital assistant, and appliances were electro-mechanical and didn’t have displays. So when you saw a new piece of tech — especially if you were a kid who didn’t know what a hacker was, but still wanted to be one — it made an impression.
I still remember the first time I even saw a tape recorder. I was amazed! But a tape recorder is a far cry from a telephone answering machine.
A Bit of Background
My Dad always had a regular job and his side business. He had a lot of different side businesses at one time or another, but he was always concerned about missing a phone call from a customer. We had two phones: the old wall mount phone with a dial and another desk phone in the “store” (the front room of the house) which also had a dial — we were way too cheap to pay for TouchTone service.
Remember, there was no call waiting and getting a second phone line was out of the question for my frugal parents. So they were always nervous about keeping the phone line clear during the day. But if you had to leave, you might miss a call. What do you do about that?
Continue reading “The Bad Old Days of Telephone Answering Machines”
Modern handheld gaming hardware is great. The units are ergonomic powerhouses, yet many of us do all our portable gaming on a painfully rectangular smartphone. Their primary method of interaction is the index finger or thumbs, not a D-pad and buttons. Shoulder triggers have only existed on a few phones. Bluetooth gaming pads are affordable but they are either bulky or you have to find another way to hold your phone. Detachable shoulder buttons are a perfect compromise since they can fit in a coin purse and they’re cheap because you can make your own.
[ASCAS] explains how his levers work to translate a physical lever press into a capacitive touch response. The basic premise is that the contact point is always touching the screen, but until you pull the lever, which is covered in aluminum tape, the screen won’t sense anything there. It’s pretty clever, and the whole kit can be built with consumables usually stocked in hardware stores and hacker basements and it should work on any capacitive touch screen.
Physical buttons and phones don’t have to be estranged and full-fledged keyswitches aren’t exempt. Or maybe many capacitive touch switches are your forte.
Continue reading “Print Physical Buttons for Your Touch Screen”
During the early years of cell phones, lifespan was mainly limited by hardware (buttons wearing out, dropping phones, or water damage), software is a primary reason that phones are replaced today. Upgrades are often prompted by dissatisfaction with a slow phone, or manufacturers simply stopping updates to phone software after a few years at best. [Oliver Smith] and the postmarketOS project are working to fix the update problem, and have begun making progress on loading custom software onto cellphone processors and controlling their cellular modems. Continue reading “Unlock & Talk: Open Source Bootloader & Modem”
For sturdy utilitarianism, there were few designs better than the Western Electric Model 500 desk phone. The 500 did one thing and did it well, and remained essentially unchanged from the mid-1940s until Touch Tone phones started appearing in the early 70s. That doesn’t mean it can’t have a place in the modern phone system, though, as long as you’re willing to convert it into a cellphone.
Luckily for [bicapitate], the Model 500 has plenty of room inside the case once the network interface is removed, because the new electronics take up a fair bit of space. There’s no build log per se, but the photo album makes it clear what’s going on. An Arduino reads the hook switch and dial pulses, while a Fona GSM module takes care of the cellular side of things. It looks like a small electret mic and a speaker replace the original transmitter and receiver. As a nice touch, the original ringer is used, but instead of trying to drive it electrically, [bicapitate] came up with a simple cam mechanism on a small motor. Driven at the right speed, the cam hooks the clapper arm, rings one bell, then releases it to let the clapper spring back to hit the other bell. Everything is powered by a LiPo, so it could be taken to the local coffee shop for some hipster hijinks.
We’ve seen similar retro-mods like this before using phones from all over the world; here’s a British take and one from Belgium, both using phones with equally classic lines.
What is more fun than plugging in your phone and coming back to find your battery on empty? Stepping on a LEGO block with bare feet or arriving hungry at a restaurant after closing probably qualify. [Alex Sidorenko] won’t clean your floors or order you a pizza, but he can help you understand why cheap chargers won’t always power expensive devices. He also shows how to build an adapter to make them work despite themselves.
The cheapest smart device chargers take electricity from your home or car and convert it to five volts of direct current. That voltage sits on the power rails of a USB socket until you plug in a cable. If you’re fortunate, you might get a measly fuse.
Smart device manufacturers don’t make money when you buy an off-brand charger, and they can’t speak to the current protection of them, so they started to add features on their own chargers to protect their components and profit margins. In the case of dedicated chargers, a simple resistor across the data lines tells your phone it is acceptable power. Other devices are more finicky, but [Alex Sidorenko] shows how they work and provides Eagle files to build whatever flavor you want. Just be positive that your power supply is worthy of the reliability these boards promise to the device.
Now you know why connecting a homemade benchtop power supply to a USB cable seems good on paper but doesn’t always get the job done. Always be safe when you make your own power supplies.
When project inspiration strikes, we’d love to do some quick tests immediately to investigate feasibility. Sadly we’re usually far from our workbench and its collection of sensor modules. This is especially frustrating when the desired sensor is in the smartphone we’re holding, standing near whatever triggered the inspiration. We could download a compass app, or a bubble level app, or something similar to glimpse sensor activity. But if we’re going to download an app, consider Google’s Science Journal app.
It was designed to be an educational resource, turning a smartphone’s sensor array into a pocket laboratory instrument and notebook for students. Fortunately it will work just as well for makers experimenting with project ideas. The exact list of sensors will depend on the specific iOS/Android device, but we can select a sensor and see its output graphed in real-time. This graph can also be recorded into the journal for later analysis.
Science Journal was recently given a promotional push by the band OK Go, as part of their OK Go Sandbox project encouraging students to explore, experiment, and learn. This is right up the alley for OK Go, who has a track record of making music videos that score high on maker appeal. Fans would enjoy their videos explaining behind-the-scene details in the context of math, science, and music.
An interesting side note. Anyone who’s been to Hackaday Superconference or one of the monthly Hackaday LA meetups will likely recognized the venue used in many of the OK Go Sandbox videos. Many of them were filmed at the Supplyframe Design Lab in Pasadena. It’s also nice to see AnnMarie Thomas (Hackaday Prize Judge from 2016 and 2017) collaborated with OK Go for the Sandbox project.
While the Science Journal app has provisions for add-on external sensors, carrying them around would reduce its handy always-available appeal. Not that we’re against pairing smartphones with clever accessories to boost their sensing capabilities: we love them! From trying to turn a smartphone into a Tricorder, to an inexpensive microscope, to exploring serious medical diagnosis, our pocket computers can do it all.