3.5mm stereo connectors for headphones and microphones are almost mandatory for audio projects. X1 (left) is a simple plug with connections for the audio channels (pin 2,3), and ground (pin 1). X2 (right) has pass-through contacts (pin 2,3) that divert audio to an internal speaker when headphones aren’t connected.
Here’s a breakdown of the audio connectors illustrated above. Continue reading “Parts: 3.5mm Stereo Audio Jacks”
SD cards add cheap persistent memory to your project, but the holder takes a lot of board space. A smaller option is the microSD flash format. MicroSD cards are compatible with regular SD cards, and most come with a free adapter. We looked at four holders for our mini web server. Which should you choose? Read about our experience below. Continue reading “Parts: MicroSD Memory Card Holders”
Most ICs need to be decoupled from their power supply, usually with a 0.1uF capacitor between each power pin and ground. Decoupling is usually used to remove noise and to smooth power fluctuations. Every project will need a few decoupling capacitors; our mini web server project has three ICs that require a total of 11. This can be an expensive part to buy in singles, so it’s crucial to stock up online. Read more about our favorite bulk through-hole and surface mount decoupling capacitors after the break. Continue reading “Parts: 0.1uF Decoupling Capacitors”
Every project needs a power supply. As 3.3volt logic replaces 5volt systems, we’re reaching for the LM317 adjustable voltage regulator, rather than the classic 7805. We’ve found four different hobbyist-friendly packages for different situations.
A simple voltage divider (R1,R2) sets the LM317 output between 1.25volts and 37volts; use this handy LM317 calculator to find resistor values. The regulator does its best to maintain 1.25volts on the adjust pin (ADJ), and converts any excess voltage to heat. Not all packages are the same. Choose a part that can supply enough current for your project, but make sure the package has sufficient heat dissipation properties to burn off the difference between the input and output voltages.
Continue reading “Parts: LM317 Adjustable Voltage Regulator”
Electronics parts can be a pain to choose. It’s often hard to tell from manufacturers’ datasheets if a part will fit your design. We auditioned six different tactile switches to find a cheap button to use in upcoming projects. A tactile switch, also called a momentary button or push-to-make switch, is commonly used for input and microcontroller resets. This type of button creates a temporary electrical connection when pressed.
Footprints for most of these buttons are available in the Cadsoft Eagle library switch-tac, or in the Sparkfun parts library under TAC_SWITCH. Buttons in the image above are discussed from left to right. Continue reading “Parts: Tactile Switches For Your Next Project”
When Boing Boing Gadgets posted about this $13 robot hand music box, we immediately thought “OH EXPLOITABLE!”. Over the years, we’ve acquired quite a bit of cheap trash just operating under the assumption that we would turn it into something else. Most of our acquisitions are Woot‘s fault. Just this morning we were dismayed to find out that the purveyor of cheap electronics had already sold out of animatronic Elvis heads. Now that would have been fun. We’ve purchased things like Tony Hawk helmet cams, jumbo remotes, Bluetooth headphones, Gyration mice, IMFree chatpads, and many other items of questionable use thinking that some day we’d use it. How about you? What sort of irrational purchases have you made and what would you do with a $13 mechanized hand?
[Just as we were wrapping this up, Woot posted a $49 HMD; you better believe we bought that.]
[Chris Kuethe] shows how to scavenge what could be a pricey WWVB module from a radio controlled clock. WWVB is a special radio station in Colorado that transmits an atomic-clock-derived signal to RC clocks. The clock model he uses, the Atomix 13131, goes for less than twenty bucks. He also shares the link to another tear down of a Sony branded radio controlled clock for similar purposes. So if you’re looking for a cheap way to obtain a WWVB module, the scavenging method could be the thrifty solution you seek.
(Disclaimer: A sticker for an event I organize is in the background of the photos, it’s not meant to be there as product placement.)
