Archive for General

Tutorial on Microwave and mm-Wave Components and Modules


In this episode Shahriar demos various microwave and mm-wave connectors, components and modules. The purpose of this video is to help new engineers become familiarized with microwave components and help reduce the chance of component damage and failure.

This video demonstrates microwave connectors (BNC, SMA, 3.5mm, 2.92mm (K), 2.4mm, 1.85mm (V), 1.0mm), interfacing instructions, attenuators, power splitters (both resistive and reactive), phase shifters, mm-wave cables, AC coupling caps, Bias-Ts and their principle of operation, mixers, tuning stubs, couplers, switched attenuators, microwave filters, multipliers, amplifiers, coaxial to waveguide converters, waveguide components including horn antennas, and directional couplers. The video also demonstrates Cascade GSG probes and GGB custom composite RF probes. The documents for this video can be downloaded from here.


Teardown and Repair of an Agilent E4421A Synthesized Signal Generator


In this episode Shahriar repairs an Agilent E4421A synthesized signal generator purchased from eBay. The unit displays the error messages “UNLOCK” and “UNLEVEL”. The cause of failure is investigated and traced. Alongside the repair efforts, the internal construction and components of the synthesizer are also presented. A short tutorial on the advantages and disadvantages of using a Darlington transistor is also presented as well as the schematic of a simple Darlington based voltage regulator. The documents for this tutorial can be found here.


Tutorial and Experiments on Magnetic Levitation


In this episode Shahriar demonstrates one of the simplest magnetic levitation circuits. First, the basic concept of magnetic levitation is examined. Two different methods of detecting the location of the levitating object is presented and the Hall effect sensor method is chosen. A semi-digital overall system is implemented where a PWM control IC is employed to control the magnetic field strength. The block diagram and functionality of this IC is presented. Finally, the schematic of a dual-Hall effect sensor solution is presented. The circuit is built and tested in both open-loop and close-loop configuration. Magnetic levitation is demonstrated with the capability of adjusting the levitation location. The schematic of circuit can be downloaded here and the electromagnet can be purchased from here.


Tutorial and Experiments on Energy Harvesting ICs

Energy Harvesting Tree

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.

Cryogenic Experiments on Passive and Active Electronic Components


In this episode, Shahriar investigates the theory and experimental results of the impact of extreme low temperatures on passive and active components. Liquid Nitrogen in used in a transparent glass Dewar where different components can be fully submerged in the liquid.  Various types of resistors are compared for their temperature stability. An electromagnet which uses Copper coils is used to generate a magnetic field at a constant power consumption at both extreme temperatures. The impact of liquid nitrogen on the junction voltage of an NPN device is measured as well as the frequency shift of a CMOS ring oscillator. Finally, the wavelength shift of an LED submerged in liquid nitrogen is studied. There is a puzzle at the end of this video, please share your thoughts in the comments section. All documents can be downloaded from here.