neilhao – Page 2 – Unit Engineering

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 of the toothbrush head, therefore toothbrush head will be oscillated if the permanent magnet is […]

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Preamplifier 30 MHz to 6 GHz

Hardware Notes / neilhao

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 in the Figure 2. Figure 1: Schematic of the Preamplifier (ADL5544 for fixed gain of

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Channel power measurements

Hardware Notes / neilhao

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 be changed by the user [2]. For example, the Figure 1 shows the Spectrum of

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Electromagnetic Shielding

Hardware Notes, Projects / neilhao

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 current density has fallen to 1/e (about 0.37) of its surface current density[2]. It is

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1.8 Inch TFT Screen for Raspberry Pi

Hardware Notes / neilhao

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 RaspberryPi, RaspberryPi Universal Expansion Board and the ST7735R Controller based TFT screen as Figure 1. Figure

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Measuring EMI with Homemade Magnetic Field Probe

Hardware Notes, Projects / neilhao

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 Field Probe. I implemented the design 2(a) which mentioned in the Roy Ediss's article. I

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Peripheral Boards

Hardware Notes, Projects / neilhao

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 ADXL345 & HMC5883 Module (3-axis accelerometer & 3-Axis Digital Compass) Schematics MAX3232 Module Schematics PGA112

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Raspberry Pi with Relay I/O Board

Hardware Notes, Software Notes / neilhao

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 diagrams used in this article was listed at the end of this article. Part I:

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Smart Home Portal

Projects / neilhao

– Smart home application framework Application Notes Overview Smart home portal is a web-based smart home application framework which is optimized for smartphone. Refer to the flowing system diagram, the Arm based embedded system (Raspberry Pi with add on boards) should be placed in the home which runs Web server with PHP and CGI/FastCGI supports.

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Accessing serial port via CGI script

Hardware Notes, Software Notes / neilhao

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 pySerial cd pyserial-2.5 sudo python setup.py install 2.Testing Saving following python CGI scripts to your

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