The OpenServo Project

When it comes to using servos in projects, there is a definite distinction between the cheap ones and the expensive high power and precision models. The OpenServo project gives you a couple options for enhancing your servo experience. By replacing the control board with a new one based on a familiar microcontroller, a whole new set of features can be attained. For those of you out there with a need for servos like these, you can buy the pre-built replacement board (unfortunately sold out right now), or build your own from the provided schematic, BOM, and source code.

Lessons In Electric Circuits

Are you looking for a good source of information to get started into making and hacking electric circuits? We would like to refer you to Lessons in Electric Circuits. Even if you have good knowledge of electronics, this is another tool you can use. The book is a work in progress and will have some incomplete and pending areas, but the basic theory parts to get started are all there. It has six volumes: DC, AC, Semiconductors, Digital, Reference, and Experiments. The DC and AC volumes are the most complete. If your eyes are already glazing over thinking you already know all of this stuff, then the most interesting volume for you may be the Experiments, which contains a number of sample circuits like transistor amplifiers and 555 timer circuits. The best part of this book it that it is free, but as with most free things, you can make it better by contributing.

Via Adafruit Industries.

Beginner Concepts: LEDs And Laws

Adafruit has a new LED tutorial for people wanting to get started with electronics. It is full of useful diagrams, pictures, and quizzes to help make sure you are understanding the concepts. This is the real basic stuff here: LEDs, resistors, and the laws from Kirchhoff, and Ohm. It starts out explaining the parts of an LED. Then variations of LEDs: illumination versus indication, clear versus diffused, brightness, color, and size. The mass of the tutorial covers how and why an LED’s brightness can be changed by a resistor and why a resistor is needed to keep an LED from burning out. Such as how Kirchhoff’s Voltage Law works with Ohm’s Law to help you determine the proper resistor for an LED. If you found useful the other beginner concepts posts about Analog Circuits and Electronics basics from the Giz, you should find this tutorial to be useful.

Making Point Contact Transistors

[youtube=http://www.youtube.com/watch?v=vmotkjMSKnI&w=470]

[Jeri Ellsworth] is back at it again. We seem to cover her work a lot here. Her latest video above covers how she created a point contact transistor from a 1N34 germanium cat whisker diode. After opening the glass casing on the diode, she uses sharpened phosphor bronze metal from common electrical connectors as the collector and emitter. A 330 microfarad capacitor charged to 20 volts and then discharged though a 680 ohm resistor to the base and collector leads forms the collector region. Her test jig is a simple oscillator circuit such that a properly formed transistor will start the circuit oscillating and make and audible sound. We look forward to more esoteric knowledge of electronic devices being brought to our attention.

How To Design Your Gears

[Dustyn Roberts] takes us through the process of designing gears for a specific application. Using Inkscape and Ponoko.com [Dustyn] takes us from equation to physical gear. While there is a plugin for Inkscape that allows you to basically drag and drop gears, this writeup will take you through the math to get exactly what you need. Those laser cut wooden gears are pretty cool looking too.

Parallax RFID Reader For Ten Bucks

We  received a tip about Radio Shack putting Parallax’s RFID reader on clearance for around $10. The only reference we could find that indicated Radio Shack sold the reader was a review page. The reader originally sold for around $50 in the stores, so getting it for $10 made it worth a curiosity trip to a local Radio Shack. The store we visited did not have the reader marked down in the drawer, but it rang up for $9.97. It is too bad that the reader was so expensive in the first place, otherwise Radio Shack might still be selling them at full price. This is by no means a promotion, we just though we would share the information in case you were interested in getting one yourself. If Radio Shack is out, you could always build your own reader.

The reader we purchased only came with one tag, perhaps that is why the they have been on clearance. Hooked up to an FTDI USB to serial cable, it would repeatedly send out the tag’s number whenever it was in range. We tried an HID-labeled card and a tag of the kind that can be found in books and DVD cases. Neither worked with the reader, but we’ll keep looking.

Thanks to [bluewraith] for the tip.

DB9 Form Factor USB-RS232 Replacement

If you’re attached to that favorite DB-9 interfaced device you should look into this part. FTDI is selling a USB-RS232 adapter as a replacement for DB-9 connectors. They come with USB male or female connections depending on the application and have the same serial footprint and pinout to which you’re accustomed. Using converter cables is just fine but this simplicity requires a few minutes of desoldering, rather than redesigning, etching, and populating a board in order to give that older design built-in USB connectivity.

[Thanks Juan]