Florian Wolters wrote an article on automated channel switching for POCSAG/DAPNET transmissions on MMDVM system: With the integration of POCSAG/DAPNET features into the MMDVM/MMDVMHost I came to think about if it would be possible to combine an MMDVM repeater/HotSpot with a DAPNET tranmitter. The advantage in Germany is that there is a single coordinated frequency […]
Author Archives: DP
#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 […]
Yet another Masterplay clone
Dr. Scott M. Baker made a Masterplay clone: The Masterplay was originally a device that allowed Atari 2600 digital joysticks to be used with the Atari 5200. In this post, I describe a masterplay clone that I created. The analog controllers for the Atari 5200 are (in)famous for their poor feel and performance. The analog […]
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: Power battery charger application guidelines
App note from Holtek on smart battery chargers. Link here (PDF) Battery chargers usually are products which transfer alternating currents to low voltage direct currents and which are widely applied in various rechargeable battery application fields. According to different applications, battery chargers can be divided into two types, namely digital chargers and power battery chargers. […]
App note: I/O emulated UART baud rate calibration
Software/bitbang method of baud rate calibration for micro without built-in UART, App note from Holtek. Link here (PDF) Not every HOLTEK MCU contains a Universal Asynchronous Receiver/Transmitter function, otherwise known as a UART. If this function is required, it can be emulated using software. However, the software accuracy will change according to the system frequency […]
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 […]
ESP32 AM radio transmitter
A how-to on making a simple AM radio transmitter using the ESP32 microcontroller by Bitluni: AM Radio transmissions are based on a carrier signal which is modulated by the audio signal. It’s a very basic principle but prone to noise from the environment. Using the ESP32 it is really simple to generate an analog signal […]
Project PITA: Build a mini mass deauther using Bettercap and a Raspberry Pi Zero W
evilsocket shared a how-to on making a mini WiFi deauthenticator using Bettercap and a Raspberry Pi Zero W: A few days ago I started playing with some idea I had from a few weeks already, using a Raspberry Pi Zero W to make a mini WiFi deauthenticator: something in my pocket that periodically jumps on […]
#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 […]
Inside a two-quadrant power supply – Agilent 66312A teardown and experiment
Kerry Wong did a teardown of an Agilent 66312A dynamic measurement DC source: Typically, a lab power supply can only operate within a single quadrant. Take a positive voltage power supply for example, it can only output or source current. If any attempt is made trying to sink current into the power supply by connecting […]
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: Minimizing light flicker in LED lighting applications
Another application notes from Richtek this time on LED lamps flickering. Link here Applying LEDs in offline retrofit lamps seems straightforward, but should be done with care to achieve similar light quality as the conventional lamp that the user is trying to replace. Light flicker is one of the aspects that need to be considered […]
App note: Li-ion battery and gauge introduction
Richtek app note for Li-ion battery definitions and gauge introduction. Link here SOC is defined as the status of available energy in the battery and usually expressed as percentages. Because the available energy change depends on different charging/discharging currents, temperatures and aging effects, the SOC could be defined more clearly as ASOC (Absolute State-Of-Charge) and […]
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 […]
Pocket high voltage generator quick build
Aki made this DIY pocket HV generator: There are times you find yourself looking for a relatively high voltage (100V to 200V often in my case) but low current DC power supply. I have zener diodes that are higher than 30V, which makes the lab supply useless, and filament LEDs with forward voltage over 60V. […]
Two bits per transistor: high-density ROM in Intel’s 8087 floating point chip
Ken Shirriff has a great write-up about the multi-level ROM in Intel’s 8087 floating point chip: The 8087 chip provided fast floating point arithmetic for the original IBM PC and became part of the x86 architecture used today. One unusual feature of the 8087 is it contained a multi-level ROM (Read-Only Memory) that stored two […]
#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 […]
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: Light guides
Light guide basics app note from OSRAM. Link here (PDF) Light Guides are used wherever the light of a light source should be distributed homogeneously over a particular area, when there is a spatial distance between light source and the area which is to be illuminated.