Warren Young of Tangentsoft writes:
Experienced audio DIYers are familiar with monolithic linear regulators like the 78xx series and the LM317. Here’s a simplified block diagram of a standard linear regulator, from National Semiconductor’s Application Note 1148
Let’s see… We have an op-amp, a couple of transistors, a voltage reference, and a few resistors. Can we build a linear regulator from these individual components? Yes, we can!
Rupert Hirst writes:
A long awaited refresh, to my previous “Anti Thump” headphone output delay circuit, designed back in 2011.
The Idea behind the circuit is to introduce a small delay, during initial power up, to electrically isolate and protect equipment connected directly to an amplifier. Often, during power up, amplifiers can produce an audible thump, through speakers or headphones. This can lead to damage of the connected equipment over time.
Thumps and clicks will occur when the supply rails voltages are too low to allow the amplifier to control its output voltage.
As the circuit has an immediate disconnect when powered off, most instances of turn off thump are also dealt with, such as output capacitor discharges.
Parallax has released the zip file containing the SPIN source code for the Parallax Propeller based DEFCON 22 badge. As noted in a previous post, the links to the schematics are also available on the Parallax website.
ReturnZero published a stroboscope build:
At its heart, a stroboscope is just a rectangular wave generator hooked up to a light source. I wanted a few extra features to make it nice to use:
- Ability to set flash rate by either frequency or RPM
- Set duty cycle of output without affecting flash rate
- LCD display
– 2×16 for displaying RPM, frequency and duty (one per line, so one will be hidden at any time)
- Rotary encoder (with button) for main interface
– When button is not pressed, knob will increase/decrease the value of the selected digit
– When button is pressed, rotating knob will scroll through display digits
- Buttons for quickly halfing/doubling thirding/trebling the flash rate
– This is useful for checking that you haven’t hit on a multiple of the rotation rate
- Nice beefy output stage for switch big sets of LEDs
OSHWA recently opened registrations for the Open Hardware Summit 2014! The Summit is Free for all and will happen in Rome in the same week of the Maker Faire:
The 2014 Open Hardware Summit will take place on September 30, 2014 and October 1, 2014 at the Rome Auditorium. This annual conference is organized by the Open Source Hardware Association. This year Open Hardware Summit is part of Rome Innovation Week.
The 2014 Summit is a two day event featuring speakers, keynotes, and workshops centered on the topic of the Open Source movement. This is the fifth year of the Summit and the first time it will be held outside the USA.
Visit OSHWA page for more information and to register.
herpderp shares his waveform generator in the project log forum:
Here is my last project, a tiny waveform generator based on my previous project and some components:
– An AD9834 (DDS chip with sinus/triangle output)
– 2 x AD5310 (10bit DAC: one for the Vpp control, another one the offset control)
– 3 x LM7171 (Fast OPA)
– 3 x LT1616 (switching regulator: +5V, +7V, -7V)This waveform generator is directly powered by a standard 12V jack and is capable of outputting a 10Vpp signal at 1MHz (between -5V and +5V, sinus waveform, no load). Above 1MHz, the output starts fading, reaching only 9Vpp at 4MHz (maximal frequency). Frequency, amplitude and offset are digitally controlled through the smart TFT.
Three “basic” waveforms are provided: sinus and triangle, coming from the DDS chip (0.1Hz to 4MHz, 0.1Hz step), and PWM coming from the microcontroller (0.1Hz to 1MHz, variable steps).
Check out the video after the break. Continue reading “Tiny waveform generator”
Prior to delivering a presentation at today’s DEFCON, hardware hacking guru Joe Grand gave this talk at BSidesLV held August 5-6, 2014 in Las Vegas. Joe describes, “[s]uperpowers, normally used by superheroes in the battle of good versus evil, are also accessible to engineers and hackers in equipment used for failure analysis and verification of PCB fabrication and component assembly processes. This presentation examines the use of lasers, X-rays, and sound waves to aid in the reverse engineering of electronic products and circuit boards.”
A 33 page PDF of the slides is available for download.
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:
Power sequencing from Analog Devices using their ADP5134 sequencer IC. App note here (PDF)
Power supply sequencing is required for microcontrollers, field programmable gate arrays (FPGAs), digital signal processors(DSPs), analog-to-digital converters (ADCs), and other devices that operate from multiple voltage rails. These applications typically require that the core and analog blocks be powered up before the digital input/output (I/O)rails, although some designs may require other sequences. Proper power-up and power-down sequencing can prevent both immediate damage from latch-up and long-term damage from electrostatic discharge (ESD). In addition, sequencing the supplies staggers the inrush current during power-up, an especially helpful technique in applications operating from current-limited supplies.
A battery monitoring chip STC3100 from STMicroelectronics tells you voltage, current, battery temperature and additionally coulomb counter for gas gauge. App note here (PDF)
The STC3100 battery monitoring function includes the measurement of the battery voltage and current, measurement of the IC’s die temperature and computation of the battery charge variation (Coulomb counter). An external sense resistor is used in series with the battery to adapt the current measurement to the application requirements.
Solutions for radio frequency electromagnetic interference in amplifier circuits from Microchip, app note can be found here:
EMI is a real problem today and it can affect most electronic devices, including medical and avionics equipment. Modern devices include EMI filters to ensure the proper operation of equipment in harsh EMI environments.
This application note demonstrates that the EMI-hardened op amps are more efficient in rejecting high-frequency EMI than standard op amps. It also shows how standard op amps can reject EMI using external filters.
Several examples have been used to demonstrate the EMI performance of Microchip amplifiers, and to discuss how EMIRR is measured and characterized.
An app note (PDF!) from Freescale Semiconductor providing a complete solution to demodulating communication signals from power wave with MC56F8006 DSC:
This application note aims to describe the Qi communication data demodulation design for wireless charger transmitter with MC56F8006 digital signal controller (DSC) including Qi communication interface, demodulation circuits design, and demodulation software design.
Wanted a LTE SIM card for Hong Kong so ran up to Aplui street. There’s a few electronics stores here but it’s pretty tame. Once a someone said their factory contacts always brought them from China to Hong Kong to buy components, once they experienced Huaqiangbei they felt duped.
If you’re in Hong Kong on the way to Shenzhen and need a SIM, Aplui Street at Sham Shui Po stop is a good bet.
You’ll see tables of SIM cards like this. All with a value like 98HKD marked down to like 45HKD ($6).
We’ve used One2Free for years now. It seems like a good mix of speed and cost. Recently, while setting up a new account, I came across an interesting discussion about 온라인 슬롯 and how these online games have grown in popularity due to their accessibility and engaging features. After you buy the card, you have to send an SMS or make a call to activate it. That might be difficult if you don’t know anyone, but the stand will usually help.
The package may or may not reveal that you can dial certainly codes to activate data bundles. My favorite is 300MB for 30days costing around 38HKD ($5). The codes I know are:
*101*833*2# 38HKD 300MB for 30days
*101*833*3# 88HKD 1GB for 30days
*101*832*3# 28HKD Unlimited for 1day
*101*832*4# 78HKD Unlimited for 1week
There is also an annoying interactive SMS menu available at #109# with all the current options.
Spacewrench over at Dorkbotpdx writes:
I had some spare 4-digit 7-segment LED displays and some AT90USB82s, and I’d always intended to do something with them. This was probably the easiest thing! It’s just the AT90 driving the display, with a(t least) 4 wires controlling it: Vcc, GND, MOSI and SCK. (
I haven’t written the code yet, but my plan is to makethe display accepts characters via SPI and then spends the rest of the time displaying them).
The board has footprints for a 16MHz crystal and USB connector, so you could make it a USB-enabled 7-segment display as well. I stuffed those parts on my test board, but I’m not sure whether the USB actually works. You can power the display from USB, at least, although the video shows it being powered over SPI (which is the same connection I use to flash code).
Check out the video after the break. Continue reading “Standalone SPI 7-segment display”
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”
Parallax has announced the details on the DEFCON 22 badge. “The badge is based around the Propeller P8X32A 32-bit Multicore Microcontroller. The circuit consists of a Propeller (microcontroller, EEPROM, clock), an infrared LED and receiver for badge-to-badge communication, a bank of eight LEDs for visual feedback, four button touch pads and a USB circuit for data access and programming. Most importantly, this badge is useful well beyond DEFCON because it’s a complete Propeller development board. All I/Os, Vss, Gnd connections are clearly ported to the side of the badge so you can solder directly to the I/O pins or jump them off to a breadboard.”
Visit the Parallax DEFCON badge forum page for links to Badge Schematics, DipTrace Layout, as well as all related Propeller software tools. (After the con, they will release a zip file containing the Spin/ASM Badge Firmware.)
This is the second time DEFCON has based a badge on the Propeller, the first being DEFCON 20 in 2012. (We hope there will be an official sale of DEFCON 22 badges to hackers post con, as there was with the 2012 edition.)
Here’s a summary of major developments over the last week. Free PCB Friday is coming up soon.
Coming up:
Here’s a voltmeter clock project based on a multimeter clock design by Alan Parekh:
I have used three voltmeters and mounted them on a wooden plinth with a clear Perspex cover to give the clock an industrial look.
I have modified Alan’s code to run on PICBasic Pro version 3. I have also added the following.
Switched display On and Off (keeping battery backup as per Alan’s design) but also allows me to turn meters Off in full power mode.
Synchronization to my Master Clock every 30 seconds
Synchronized LED & Re-Synch LED
Synchronization On & Off
Transistor meter drivers
Separate hourly Chime Circuit
Pulsed “tick tock” seconds sound.
Via Hacked Gadgets.
SkinnySatan writes:
I had this one project where the device was supposed to speak out the output. And I was too Lazy to actually go and build a PC based application and not that lazy to make it on a micro controller. So here is some of my research where i am gonna show you how to do speech synthesis for your Embedded Project.
Why I am Implementing it on a Microcontroller?
-Its Cheap
-Its Portable
-Its Fun
-Its Easy ( Yes! Once you Port it on your platform, it is)
What do we need here.
-A low power Speaker (8 Ohm one will match the impedence)
-A Micro controller with PWM generation possible and lots of memory ( We are using Atmega128)
-A low pass filter adjusted on 8Khz Band.
DEFCON badge master Ryan Clarke has revealed the design for this upcoming weekend’s DEFCON 22 conference credentials. “The badge features a circuit board and several LEDs. Buried within it, however, are crypto-puzzles, electronic Easter eggs, and a backstory about things that aren’t what they seem. The underlying theme riffs on John Carpenter’s 1988 sci-fi cult classic They Live about a shaggy-haired drifter named John Nada who stumbles upon a box of mysterious sunglasses.”
While hardware details have not yet been revealed, we expect to find them online within the next few days.
Via WIRED.
