A short introduction to how Bitcoin Works. Written version:http://www.imponderablethings.com/2014/04/how-bitcoin-works-in-5-minutes.html
A somewhat technical, but concise explanation of how Bitcoin works.
This video demonstrates the use of solder wick (braid), a solder sucker (desoldering pump), and desoldering gun. It explains why some joints are hard to desolder: large ground planes or components, small holes, low quality pcbs. Finally, some alternative methods are shown, including cutting the leads, pulling one lead out at a time for resistors and other two-legged parts, and heating all the pins at once, using an iron, hot air or ChipQuik.
This sms-to-LED tutorial shows how to automate the manual button input on this $13 scrolling LED belt buckle with an arduino, and then how to pass SMS messages through it. A USB Host shield connects an android phone that passes SMS messages on. Full code is on the tutorial page.
The Scanalog 2 is a great inexpensive tool for hobbyists looking to debug digital issues, especially if they can’t afford an oscilloscope. Debug SPI, I2C, Serial UART, 1-Wire, Maple Bus (more to come with software updates). You can even inspect that PWM or RC servo signal to make sure your arduino is outputting what you think it should.
- 20Msps on 4 channels
- 1.8V – 5V level detection
- 256k samples of storage on each line
- Playback on all 4 lines, or just 2 while reading from other 2
- Better Triggering
- More flexible output–static pwm to control RC servos, for instance, or just for a clock generator.
Here’s a quick video of drag soldering–a technique that enables you to quickly solder entire sides of ICs by simply dragging the iron across all the pins. The key is starting with the right amount of solder, and adding generous flux. The results are often better and more uniform than individual pin soldering.
A common mistake we’ve seen in our classes–as well as from experienced ‘solderers’–is to clean the tip before putting the iron back in its stand. This habit leaves the tip exposed to oxygen in the air which works quickly to oxidize (basically rusting) the end of the tip. Almost all metals oxidize in air, and they do so much faster at higher temperatures. When your tip is thoroughly oxidized, it will look burnt, and no solder will stick to it. And if solder won’t stick to it, you won’t be able to create a “heat bridge” of solder between the iron and part, and very little heat will transfer.
To avoid this, coat the tip with a large blob of solder every time before returning it to its stand. While flux in the solder gradually eats away at the tip, oxidation will cause problems much faster.
You may notice that new tips actually come coated with solder. We’ve seen manufacturer documentation recommending that you hold solder against a new tip the first time you heat it up so that the tip gets coated as soon as it’s hot enough to melt solder.
Cleaning tip: If your tip is starting to look brown, and won’t ‘hold’ solder, or the solder acts like water on a freshly waxed car, you can help restore it by repeatedly applying solder and wiping it off. The flux in the solder acts like a cleaning against against the built up oxides. It may take 20 or more cycles of this to get the tip back into shape.
Here’s an instructable showing how to Control a Hand Drill with an Arduino / roboduino to spool solder. This may not be on the top of everyone’s project list, but a hand drill is strong enough to do a lot of tasks, so we hope this will be helpful to someone with another project idea,… maybe spooling guitar pickups.
Rather than use TRIACs to mess with the 120VAC, we found a servo was an easy and safe way to control the drill’s trigger / throttle. The setup also uses a home made optical encoder that triggers an interrupt in the arduino code. The code is available Solder_spooler_v3_pde, and contains some useful bits like lookup-table speed control, state machine menu system, and interrupt based speed sensing.
While SMT leds typically have a dot or small green line indicating their cathode, it can be hard to remember. A quick way to test a LED is by touching the ends with a multimeter in ‘Continuity Test’ mode. The multimeter generates a small voltage in order to detect a closed circuit, and this is enough to light the LED. Although we couldn’t burn out any LEDs with this Fluke, there’s no guarantee your meter won’t over-do the current, so we recommend doing just a quick touch, or putting a resistor in line.