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Philips Sonicare Electric Toothbrush Measurements without Teardown
Part I: Sonicare Electric Toothbrush Architecture Figure 1: Sonicare Electric Toothbrush Architecture This electric toothbrush is a water-resistant design, thus it adopts wireless charging technology. Coil 2 is the wireless charging receiver. A permanent magnet is attached to the trail…
Preamplifier 30 MHz to 6 GHz
Part I: Introduction I designed two preamplifiers which can be added to any application needs additional gain. The two designs have the same PCB layout but different IC U1 which is shown in the Figure 1. The PCB is shown…
Channel power measurements
Part I: Understanding the RF Spectrum Measurements The Spectrum Analyzer has a bandpass filter (IF filter) which is used as the "window" for detecting signals. The bandpass filter's bandwidth is also called the resolution bandwidth(RBW) of the analyzer and can…
Electromagnetic Shielding
Part I: Selecting the Proper Shielding Materials At first, we need to introduce a physics concept Skin Depth, before discussing the shielding materials. The Skin Depth δ is defined as the depth below the surface of the conductor at which the…
1.8 Inch TFT Screen for Raspberry Pi
This is a short Application Note about how to use ST7735R Controller based TFT screen with RaspberryPi Universal Expansion Board and RaspberryPi. More information about the screen can be found in the list of my Peripheral Boards. Part I: Hardware Connect…
Measuring EMI with Homemade Magnetic Field Probe
Part I: Magnetic Field Probe The theories behind the Magnetic Field Probe (Near Field Probe) is not very complex. Roy Ediss well stated the theories and the various designs of the Magnetic Field Probes in his article, Probing the Magnetic…
Peripheral Boards
The Peripheral Boards which are designed by myself will be listed in this page. Pmod-Compatible Modules (Designed for Xilinx ZedBoard, Altera DE2-70, etc.) Application Notes Altera DE2-70 FPGA Development Board to Pmod Converter Schematics AD5623 & AD7274 Module (ADC/DAC) Schematics…
Raspberry Pi with Relay I/O Board
Relay I/O Board is widely used in applications of smart home project. In this article, I will detail how to control the Relay I/O board using Raspberry Pi with Raspberry Pi Universal Expansion Board via internet. The codes and schematic…
Accessing serial port via CGI script
Prerequisites: Part 3: Using Serial Port on Universal Expansion Board Python CGI script with lighttpd (Root privileges are required) 1. Install pyserial on RaspberryPi a. Download pyserial-2.5.tar.gz (106.3 kB) b. unzipping and untaring gunzip pyserial-2.5.tar.gz tar -xvf pyserial-2.5.tar c. Install…