KF5OBS writes:
This video briefly explains how to influence a crystal oscillator’s frequency by introducing reactive elements such as trim capacitors and inductors. This example uses a very simplistic Pierce oscillator and a crystal ins series resonance.
Andrew Rohne blogged about his free Bus Pirate Demo board build:
After building my first PCB a while back and starting to attempt to use it, I decided that the smart thing to do would be to finish build #2, which is a Bus Pirate Demo Board. This demo board has a handful of chips that can be used to test a Bus Pirate (or in my case, a Bus Pirate Shield): 5 EEPROMs, a temperature sensor, a digital-analog converter, and a real-time clock.
If you build a free PCB we’ll send you another one! Blog about it, post a picture on Flicker, whatever – we’ll send you a coupon code for the free PCB drawer.
@FrozenElecBlog tweeted, “Just published a video about the Bus Pirate — love this thing!!!”
VFD clock with SNMP and NTP by Pyrofer:
It sets itself via NTP and adjusts for daylight savings time so no buttons and it never needs adjusting. It can be monitored via SNMP for logging the temperature and checking system uptime. The entire SNTP stack was written from scratch and it all fits in one AVR 328P.
For a screen I am using a salvaged VFD from an old Fruit Machine. 16 character 14 segment display with serial input.
Main control board is an ardiuno clone from eBay.
Connectivity is via a WizNet5100 board. There is also a Dallas 1-wire Temperature probe because why not?
Via Hacked Gadgets.
Boris of Open Electronics wrote an article on his stand-alone access control with RFID project:
RFID Tags are increasingly used for many applications such as identifying objects by means of a code or access control. In logistics RFIDs allows asset tracking, or monitoring conveyor belts; in shops tags are often used as anti theft. RFIDs are also used for presence detection and security, with several use cases, for example in computer and appliance access and user identification. Due to the importance of RFIDs we propose today a simple, stand-alone project, which is basically a simple transponder enabled lock. This lock is equipped with a relay to be used to control an electric gate opener or a simple lamp.
Our friends over at 2600 are once again offering a discount on tickets to their 2014 conference:
In case you weren’t one of the lucky ones who managed to snag a discounted ticket in November, we’re having a special $99 ticket offer this Wednesday (December 11, 2013) at 2 pm ET.
HOPE-X will be taking place on July 18, 19, and 20, 2014 at the
Hotel Pennsylvania in New York City. Preregistration will begin in
January at the normal price. We’re only offering 100 tickets at the $99 level on Wednesday with a maximum of four tickets per order. We sold out in under two minutes last month, so be sure to practice your quick typing skills so you can improve your chances. Remember, the order is only complete when you click the final button after entering payment info and get a confirmation message.Our website has two addresses: the super-cool HOPE X address located at xxx.xxxxxxxxxxxxxxxxxx.xxx and for those who find that difficult to remember or for whom the .xxx domain is blocked, x.hope.net.
We look forward to seeing you at HOPE-X – our tenth conference, HOPE’s
twentieth anniversary, and 2600’s thirtieth anniversary!
Ivan writes to inform us of his new site, www.info-transistor.info. “It allows you to find the technical specs of transistors (bjt, mosfet and igbt) and even put this information here in the forum with the BBCODE export option!”
Via the contact form.
Ethan Zonca of Protofusion writes:
The PogoProg is a small open source hardware pogo pin programming solution. The PogoProg does not need a physical connector on the board, it uses surface-mount pads for signals and thru-holes for alignment. Two standard footprints are available, the smallest of which takes up very little space–only 7.6mm x 1.2mm!
The PogoProg was originally designed for use with AVR microcontroller programming (using 6 pins), but this design can easily be repurposed for other programmers. Several footprints are available for this programming connector as shown on the test PCB above, but only two are recommended for real-world use: J1 (PogoProg Standard), J4 (PogoProg Micro)
Every Tuesday we give away two coupons for the free PCB drawer via Twitter. This post was announced on Twitter, and in 24 hours we’ll send coupon codes to two random retweeters.
Don’t forget there’s free PCBs three times a every week:
Some stuff:
We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.
fowkc has just published his latest project the mains frequency display:
I wanted to make a display that could show the mains frequency to 3 decimal places. I’d be using the same seven-segment display modules that I used in my UNIX clock, so all I had to do was design the part that would work out the frequency.
Ethan Zonca of Protofusion writes:
While developing the Luma RS485-networked LED driver we discovered a need for a small and inexpensive USB to RS485 adapter. We designed an adapter with a FTDI basic UART chip (FT230XS) and an inexpensive TI differential receiver (SN75176). Our small selection of parts brings the cost down to just over $5 for one adapter.
Raj did a review of Dorji’s DSTH01 digital temperature and humidity sensor module:
The DSTH01 module is smaller than 0.4″X0.4″ in dimension and operates at 2.1-3.6V power supply. The pull-up resistors for I2C lines are available on board. I tested this sensor module with Crowduino (an Arduino Duemilanove clone with Atmega328) using Jonas Bo Jalling’s Si7005 Arduino library, and worked like a charm. Crowduino has an on-board power select switch to chose the supply voltage for operation between 3.3V and 5.0V. I chose it to operate at 3.3V (although it should not matter too much as I2C lines are already pulled-up to 3.3V from the sensor module). Since the DSTH01 module interface pins are not 0.1″ standard, I soldered the pins onto a small general purpose prototyping board and made the pins accessible through a 0.1″ male header pins
Kevin Rye designed a simple LED tester:
I decide to put together a small LED Tester board. It’ll be powered by a small coin cell battery. I can pick up an LED with a pair of tweezers and just simply tap it to the solder pads. If it lights up, I know I’m holding it the right way, or not.
As far as a PCB, I want it to be super simple and super cheap. I really don’t want to spend $10 bucks on something so simple. However, I don’t want it to be a one-trick pony either. Ideally, it should work for through-hole LEDs as well, as 1206s and whatever other sizes I can’t think of right now. Do SMD LEDs come in an 0805 package? I’ve never seen one, but it’s probably a good idea to place some large pads on it so that it’ll work for anything.
SUF shared his voltage reference project in the forum:
To achieve the things above I designed a small battery good indicator circuit with a zener an opamp two LEDs and a few resistors. If you switch it on and the battery fall below 8V the red LED will lit instead of the green.
I wanted to have a SOB style case. I designed a new one with a trick on it. I used a third acrylic plate what has a hole inside. The hole can accommodate the battery and the battery clip. This setup keeps the battery in place.
Petros Koutoupis at Linux Journal posted detailed information regarding hard drive caching techniques. Users of traditional hard drives who’ve been considering a switch to a solid state drive (SSD) should find this particularly interesting. Petros describes,
Even today, the consumer SSD cannot compare to the capacities provided by the magnetic hard disk drive (or HDD), which is why in this article I intend to introduce readers to proven methods for obtaining near SSD performance with the traditional HDD. Multiple open-source projects exist that can achieve this, all but one of which utilizes an SSD as a caching node, and the other caches to RAM. The device drivers I cover here are dm-cache, FlashCache and the RapidDisk/RapidCache suite; I also briefly discuss bcache and EnhanceIO.
We go through a lot of prototype PCBs, and end up with lots of extras that we’ll never use. Every Sunday we give away a few PCBs from one of our past or future projects, or a related prototype. Our PCBs are made through Seeed Studio’s Fusion board service.
This week two random commenters will get a coupon code for the free PCB drawer tomorrow morning. Pick your own PCB.
You get unlimited free PCBs now – finish one and we’ll send you another!
Don’t forget there’s free PCBs three times every week:
Ever wonder why your project acts funny and sometimes causes unexpected outcome then one of these reasons are interference and how they inject into or emit from your designs. Learn more about EMC from Atmel’s design consideration notes.
The electromagnetic environment is getting tougher. High-frequency radio transmitters, like mobile telephones, are found everywhere. More and more systems are using switching power supplies in the power circuit, and the overall number of electronic appliances is increasing every year.
Electronic circuits are becoming more and more sensitive.
Power supply voltages are decreasing, reducing the noise margin of input pins. Circuit geometries get smaller and smaller, reducing the amount of energy required to change a logic level, and at the same time reducing the amount of noise required to alter the logic values of signals.
This application manual from Murata packs a lot of information about noises generated from most electronics equipment and what are the right filters to suppress these.
To make effective noise suppression in electronic equipment it is necessary for design engineers to have a good understanding of the various types of EMI suppression filters available and the characteristics so that they can use suitable components. Because filtering characteristics of EMI suppression filters depend significantly on the construction, a wide variety of products are available in the market, it is difficult to understand all of them.
This brochure provides an overview of EMI suppression filters by classifying them into several groups and describing the characteristics of each group along with a brief summary for the engineers.
This publication is intended to help readers to make correct selection of EMI suppression filters for their applications.
SamyKamkar developed this seriously cool project to wrest control of civilian drones away from their owners.
SkyJack is a drone engineered to autonomously seek out, hack, and wirelessly take full control over any other drones within wireless or flying distance, creating an army of zombie drones under your control.
Using a Parrot AR.Drone 2, a Raspberry Pi, a USB battery, an Alfa AWUS036H wireless transmitter, aircrack-ng, node-ar-drone, node.js, and my SkyJack software, I developed a drone that flies around, seeks the wireless signal of any other drone in the area, forcefully disconnects the wireless connection of the true owner of the target drone, then authenticates with the target drone pretending to be its owner, then feeds commands to it and all other possessed zombie drones at my will.
SkyJack also works when grounded as well, no drone is necessary on your end for it to work. You can simply run it from your own Linux machine/Raspberry Pi/laptop/etc and jack drones straight out of the sky.
You can get more details and download the code on Samy’s GitHub page.
The second type of optical sensor, here’s Vishay app note on how do they operate and their considerations when using one of these on your projects.
These sensors integrate an infrared emitter and photo detector in a single package. The most common types of optical sensors are transmissive and reflective sensors. Both types detect the presence of an object without any mechanical or electrical contact. The output signal of the sensor is used to control various functions of an application
Reflective sensors incorporate an infrared emitter and photo detector adjacent to each other. When an object is in the sensing area, the emitted light is reflected back towards the photo detector, the amount of light energy reaching the detector increases. This change in light energy or photo current is similarly usedan input signal in the
application.
