James Coxon writes: The aim was to use ESP8266 and reflash the onboard processor with the Arduino development environment to allow easy porting of the current UKHASnet code. The ESP would act as the main microprocessor and control the RFM69 over SPI. Any packets received by the RFM69 would then be uploaded by the ESP […]
Author Archives: DP
Contactless transit card teardown
A RFID transit pass teardown from Electronupdate: Here is the die photo: super tiny. I bet they get thousands of dice off of each wafer. The chip appears to be part of the MIFARE protocol, commonly used for contactless smart cards. The vendor of these chips is NXP, and based on the size and features, […]
Homebrew Raspberry pi shutdown button
Facelesstech made his own Raspberry pi shutdown button and wrote a post on his blog detailing its assembly: One thing I learn from my last shut down button was that the raspberry pi has internal pull up resistors so I didn’t need a 10k and a 1k pull up resistor on this design. This would save me a […]
Free PCB Sunday: Pick your PCB
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 […]
App note: Flow sensing in tankless water heaters
Contactless reed switches from Littelfuse provides flow and water presence monitoring. Link here (PDF) Reed switches and sensors are highly effective solutions for flow sensing applications that can be used for detecting the presence of fluid flow in a system or even measure the rate of fluid flow. Tankless water heaters are becoming a widely […]
App note: Circuit protection technology application matrix application guide
Here’s an application matrix of Littelfuse’s circuit protections, Link here (PDF)
App note: Creating a custom flash-based bootstrap loader (BSL)
An application note (PDF!) from TI on creating a custom flash-based bootstrap loader (BSL): MSP430F5xx and MSP430F6xx devices have the ability to locate their bootstrap loader (BSL) in a protected location of flash memory. Although all devices ship with a standard TI BSL, this can be erased,and a custom made BSL can be programmed in its […]
Inverter crystal oscillator
Vasily Ivanenko writes: In numerous RF synthesizer chips lies an inverter with input and output pins for making a reference crystal oscillator clock. I built some discrete chip inverter xtal oscillators with 74HC series logic gates to better examine them. You’ll quickly recognize the oft-used Pierce oscillator topology with 1 trimmer capacitor to tweak the […]
Free PCB coupon via Facebook to 2 random commenters
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. The coupon code usually go to Facebook ‘Other’ Messages Folder . More PCBs via Twitter on Tuesday and the blog every Sunday. Don’t forget there’s free PCBs three […]
Tote – Quadruped robot
Radomir Dopieralski has a nice build log on his quadruped robot – Tote: Tote is a small (fits inside your palm), four-legged, walking robot, with three degrees of freedom per leg, Arduino for its brains and controlled either with a TV remote, or by additional electronics added on top of it. It is very simple, cheap […]
TV Tuner IR remote with a PIC16F684
Tahmid built a TV tuner IR remote with a PIC16F684: I then proceeded to write an IR transmitter using the PIC16F684 (using the MPLAB X IDE and XC8 compiler), following the timing information from the extended NEC protocol. In order to connect all the keys, I connected them in matrix keypad form. In order to power the […]
Homebrew Multimode Digital Voice Modem (MMDVM) adapter
Florian Wolters made his own version of MMDVM adapter: During experiments with digital voice mode in hamradio I discovered a nice project describing an adapter for D-Star, DMR and other digital modes based on an Arduino Due and a little PCB to be put on top. This unit is called the Multimode Digital Voice Modem […]
ESP8266 temperature logger
A ESP8266 temperature logger project from Facelesstech: I decided to use the esp-01 module because I only need 2 GPIO pins since I was using the DS18B20 temp sensor and the WS2812 LED. This made the hardware really cheap and easy to reproduce too. I normally use FTDI boards when it comes to the USB to […]
9V/1kV DC/DC converter
Robert Gawron’s home insect electrocution project: Currently I’m working on a device to electrocute home insects like cockroaches, progress is small because they are smarter than I thought, but that’s a different story. For that project I had to find a source of sufficient high voltage and output power. Presented in previous post 5V/400V converter […]
#FreePCB via Twitter to 2 random RTs
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: Hate Twitter and Facebook? Free PCB Sunday is the classic PCB giveaway. Catch […]
AD9834 and the IoT beacon
m0xpd writes: I’ve been playing with a new RF generator for the IoT beacon… Actually, I do myself a disservice, because I’ve done rather more than just play with the RF generator. First, I’ve replaced the little USB to serial dongle which I used to program the original system and built a complete interface, using the […]
VXO – based PLL frequency synthesizer for 7 MHz
Vasily Ivanenko made a VXO-based synthesizer: To make a VXO to mix with a ~7 MHz VCO, you’ll need a crystal that is higher in frequency than the highest frequency you want to synthesize. Some rummaging revealed a bag of 21.4773 MHz crystals that I could divide by 3 to garner 7.159 MHz. To afford a […]
App note: Parallel configuration of H-bridges featuring the MC33932 and MC34932 ICs
Old application note from ON Semiconductors on getting increased power capability by paralleling H-bridges and overcoming current limit imbalance between the two drivers by properly designing the board layout. Link here (PDF) Two or more H-bridges can be operated in parallel to increase the current handling capacity of the circuit. In this application note, paralleling […]
Free PCB Sunday: Pick your PCB
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 […]
App note: Duty cycle and power optimization
Power saving specially on battery operated devices need to be kept, in this application note from ON Semiconductors discussed how to keep duty cycle in which a wireless RF device is operated at a minimum time. Link here (PDF) Consider a battery powered device (target), which should receive data from a second device (initiator) from […]