Boris Landoni from Open Electronics has written an article about the design of a microphone preamplifier:
This Mini Microphone Preamplifier could be used as the first stage to amplify any audio signal. The device is equipped with a microphone plus clips to be connected to a 9V battery. Amplification is achieved by using an operational LM741 amplifier. The volume level could be adjusted via a trimmer.
Ed informs us that there have been a number of improvements on the OLED backpack from Fried Circuits! It’s turning into a fairly complete logging tool, now including multiscreen support (cycle between six screens with various readings), energy measurement (measuring charge in Wh and Ah), and interrupt-based reading.
You can find details and updated information at Ed’s Aerodynes site.
Via the contact form.
Dobrica wrote a post on his blog detailing the build of his simple temperature monitor using Arduino Nano:
For a last few months, I have been playing around with Arduino and collecting useful parts for my first real project. Last week we purchased Mitsubishi air condition with super-invertor and I wasn’t totally happy with the way it operated so I took several afternoons and tried to understand how temperature in my room was varying depending on it’s settings. To do that, I built simple temperature monitor using Arduino Nano, two temperature sensors and Nokia 5110 screen. This post tries to document my journey…
Using the Maxim/Dallas 1307 RTC that runs at 5V with the Arduino Due that runs at 3V. FETs are used for bidirectional level shifter per a Philips app note. All built on a Freetronics ProtoShield of course!
Via the forum.
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:
Joe Desbonnet acquired a Silvercrest (Lidl) TwinTalker 4810 PMR radio and decided to explore under the hood. PMR radios are a European equivalent of low power Family Radio Service and General Mobile Radio Service walkie-talkies used in the USA, but operate on the 446 MHz frequency band. Most use analog FM, though commercially targeted models use a dPMR digital modulation technique. Joe posted this article outlining his findings.
Here’s an application note from Maxim describing hot-swap circuits, and the advantages of dedicated hot-swap ICs over discrete component circuits:
There are many approaches for protecting a system against electrostatic discharge (ESD), surge current, overcurrent, undervoltage, overvoltage, and other disruptions to power. Industry, company, or regulatory standards such as UL®, USB, IEEE®, CSA, or IEC often require circuit protection. This application note discusses hot-swap ICs. Typical hot-swap circuits are described and the advantages of different hot-swap circuits are explained.
Stephen Ong previously released this video demonstrating the use of RTL-SDR dongle with the BeagleBone dev board to function as a spectrum analyzer. The software making this possible is known as ViewRF and Stephen has now released the instructions and code links for this project.
Here is an app note from Maxim describing the various SMPS regulator topologies for battery powered systems:
This tutorial presents an overview of regulator topologies for battery-powered equipment. The discussion covers linear regulators, charge pumps, buck and boost regulators, inverters, and flyback designs. The importance of peak current is explained, and schematics of each topology are shown.
Radio Shack and Popular Mechanics are sponsoring a Hackerspace Challenge designed to determine which of two competing finalists best exemplifies the theme ” From something old, make something new.”
The contest pits the Milwaukee Makerspace Morgifying Marble Manipulation Machine (aka: M6) against Inspiration Labs’ Police Callbox Lander (a Biofeedback-Controlled Game) with the winner taking a $1000 prize. The winner will be decided by popular votes cast on the Hackerspace Challenge site and will be announced in the December/January issue of Popular Mechanics magazine. The contest organizers will also award a $1000 Radio Shack gift card to one randomly drawn voter!
For videos of the competing projects or to cast your vote visit Popmechnow.
Viktor blogged about his bipolar stepper motor driver based on Texas Instuments’ LMD18245 build:
After extensive research on the internet I decided to make a bipolar stepper motor driver based on Texas Instuments’ LMD18245, which is a 3A, 55V DMOS Full-Bridge Motor Driver. It incorporates all the circuit blocks required to drive and control current in a bipolar stepper motor.
Mats has amazed us with his board a week projects, and now one of them could be yours! Today Mats is giving away three TraId kits – Transistor type & pinout identifier. All parts included except for a CR2032 battery that needs to be sourced locally due to postage regulations:
TraId is a really low cost version of the Part Ninja. It’s made to only identify the pinout and type (NPN/PNP) of a transistor and display the results on eight LEDs. Currently the firmware only handles BJTs but I think FETs should be possible as well.
He’ll give these away to 3 random commenters, just leave a comment on this post.
Firmware and other files can be found on Github. For more information visit the project’s Tindie site.
Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. More PCBs via Twitter on Tuesday and the blog every Sunday.
Don’t forget there’s free PCBs three times every week:
Continue reading “Free PCB coupon via Facebook to 2 random commenters”
Mats continues his challenge of designing one PCB every week. In week 22 he came up with TraId – Transistor type & pinout identifier:
TraId is a really low cost version of the Part Ninja. It’s made to only identify the pinout and type (NPN/PNP) of a transistor and display the results on eight LEDs. Currently the firmware only handles BJTs but I think FETs should be possible as well.
TraId-kits giveaway coming up soon! Stay tuned!!
Here’s a summary of major developments over the last week. Free PCB Friday is coming up soon.
Coming up:
Here’s another cool acrylic case for the ATX Breakout board bench power supply by Phenoptix:
A rather handsome pair of acrylic plates, just a bit bigger than the ATX Breakout boards from Dangerous Prototypes. The design is heavily influenced by Seeed Studios product but we couldn’t find the files to just copy it directly. Our files are on Thingiverse.
You can get ATX breakout board bench power supply for $14 at Seeed.
Here’s a DIY laser cut cable carrier chain project by Martin Raynsford:
I’ve been looking at cheap laser cutters quite a bit recently. Most of them are missing air assist and red dot positioning, these features require wires to be run up to the laser head which means running cables around the moving parts. These drag chains can route cables safely through the machine and are usually made of plastic. Having a laser though everything looks like it can have a laser cut solution so I made my temporary ones from 2mm mdf.
Via Hacked Gadgets.
Check out the video after the break. Continue reading “DIY laser cut cable carrier chain”
Tsvetan reports some good news for the open source community:
a group of hackers (jemk, wingrime, nove) worked on the reverse engineering of CedarX and an open source driver for Allwinner chips is on the way!
Details on these efforts and links can be found at Olimex.
Via the contact form.
Alvaro wrote a post on his blog detailing how to debug LPC1769 with the Bus Blaster:
After getting the gcc-arm compiler working with the mbed, I decided to take a look at my LPCXpresso LPC1769 development board. The mbed is really easy to program. It mounts as a flash drive and you just drag and drop the binary file onto it. Unfortunately, that’s it. There is no way to get any debug information out of it. The LPCXpresso, on the other hand, comes with a nice LPC-link board attached just for this purpose. Unfortunately(again), it only works with certain IDE’s, like code_red. I cut the lpc-link board off and instead used a BusBlaster from Dangerous Prototypes along with OpenOCD.
