In this episode Shahriar takes a close look at an HP/Agilent 5347A 20GHz Frequency Counter and Power Meter. This defective unit does not provide any frequency information from Input 2 which is rated to operate up to 20GHz. Before the teardown and repair attempts, the principle operation of the instrument is reviewed.
The properties of a Step Recovery Diode (SRD) is presented along with the theory and practical aspects of generating a frequency comb. The heterodyne architecture of the frequency counter is explained in detail with the mechanism of detection and calculation of the input frequency.
During the teardown of the unit the synthesizer board, motherboard, power meter reference board and the main RF assembly are shown. The schematic of the synthesizer board and the RF board are also described. The defective component is identified and examined under the microscope. The slides for this episode can be found here.
In this episode Shahriar explores the world of Delta-Sigma modulators with emphasis on a Delta-Sigma Analog to Digital Converter (ADC). The basic concepts of analog to digital conversion is presented, particularly with respect to quantization noise spectral shape and power density. Next, oversampling ADCs are presented to demonstrate the possibility of increasing SQNR (ENOB) through manipulation of quantization noise spectrum.
Due to the practical limitations of high oversampling ratios, delta-sigma modulations is explored. The principle operation behind delta-sigma ADCs is presented with detailed explanation on noise shaping, filtering and decimation. The signal and noise transfer functions for a 1st order and 2nd order delta-sigma ADC are derived. Finally, as a practical example, a 2nd order delta-sigma ADC based on a 1-bit quantizer is presented. The ADC uses two Miller integrator op-amps, one comparator and a D-Type flip-flop. The complete measurement of this delta-sigma ADC is presented. The impact of over sampling ration, op-amp linearity and input signal bandwidth is presented. The slides for this video can be downloaded here.
In this episode Shahriar takes a close look at programming the popular NeoPixel RGB LEDs using a PIC microcontroller and C-language. A close-up of the NeoPixel (WS2812) LED is shown with attention to identifying various semiconductor elements inside the package. The principle operation of the LED is the described along with a detailed explanation of the pins and the one-wire communication protocol.
A simple evaluation board for the PIC18F4550 is used to drive a circular array of 60 NeoPixel LEDs from Adafruit. After presenting the difficulties of providing an accurate pulse-shape using the C-language, the measured waveform is shown on a Tektronix MDO4000B. Finally, the code for a circular color rotating pattern is presented and demoed. The code for the experiment can be downloaded here.
There is also equipment giveaway! A TPI Scope Plus 440 and a Tektronix TDS2232 are being given away at no charge! Please leave a comment on the video or on the website. You must be a resident of the USA to receive the giveaway. A winner will be chosen at a later date and notified via email.
In this episode Shahriar demonstrates the functionality and applications of an Agilent 11896A Polarization Controller. Various fiber optic communication methods are presented. This includes the use of complex modulation schemes (such as PAM and QAM for coherent receivers), polarization division multiplexing (PDM), wavelength division multiplexing (WDM), and spatial division multiplexing (SDM). The concept of light polarization is demonstrated by using a pair lenses from a consumer theater 3D glasses and two blue LEDs with uncorrelated lighting patterns.
In order to test the polarization controller, a solid-state laser source, SMF fiber with APC/PC connectors as well as a polarization beam splitter is presented. By using a pair of optical power sensors, the functionality of the polarization controller is verified. Finally, the teardown of the unit is presented and the method to achieve polarization control is observed.
The fiber optic communication overview document can be downloaded here. I’d also like to acknowledge my colleague and friend Dr. Timo Pfau for his expertise and consult on fiber optic communication methods.
In this episode Shahriar investigates some state-of-the-art energy harvesting ICs from Linear Technology. The LTC3105 is a highly efficient 400mA Step-Up DC/DC Converter with Maximum Power Point Control and 250mV Start-Up. After exploring the IC’s internal block diagram, the evaluation board for this energy harvesting chip is presented. Various experiments, including the calculation of efficiency, maximum power delivery, start-up behavior and MPPC are presented. As a last experiment, a two stage energy harvesting setup using a solar panel and a super-capacitor capable of charging an iPhone is demonstrated.
The second IC of interest is the LTC3109 which is an Auto-Polarity, Ultralow Voltage Step-Up Converter and Power Manager Energy Harvesting chip. The block diagram and the evaluation board of this IC is presented. The ultra-low voltage capability of the circuit is demonstrated through the use of a Peltier cooler thermo-electric component to generate a 5V output voltage. As a final experiment, several ice cubes are used in conjunction with the thermo-electric generator in order to harvest enough energy to charge an iPhone for 30 seconds.
The Signal Path (TSP) is an electrical engineering video blog for industry professionals, students and hobbyists. TSP is a non-for-profit website dedicated to provide free education spanning a wide range of electrical engineering topics. Equipment review, tutorials and repair videos are posted regularly.