Archive for Projects

Tutorial on Programming a Waveshare 7.5-Inch Multi-Color e-Paper Display & Info-Frame

In this episode Shahriar demonstrates the capabilities of a Waveshare 7.5-Inch tricolor e-Paper display. By combining the display with a Raspberry Pi Zero, the SPI interface of the mini-computer can be used to program and configure the e-Paper display using Python scripts. Furthermore, the Python script takes advantage of the available API of a few website to provide relevant information such as the current date, calendar, task list with due-dates as well as the current weather and weather forecast all in a clean user interface.

The complete Python code is presented and analyzed and the principle operation of the display is also presented. Do not forget to check Applied Science’s video on this topic as well. Finally, the individual pixels are examined under the microscope while the screen undergoes a refresh which demonstrated how various colors are displayed.

The complete code can be downloaded here. You can also buy the e-Paper display here and the Raspberry Pi Zero kit here. If you are interested in using an ESP WiFi module with Arduino to interface with the e-Paper display, it can be found here. You can chose any picture frame to complete the project. The Task Manager and Weather APIs can be found here and here.

Quest for mm-Wave Capability: Teardown, Analysis & Experiments on Generation & Detection

In this episode Shahriar demonstrates the effort for collecting affordable components and instruments in the past year to be able to generate mm-wave frequencies in the lab. The main goal is to generate synthesized CW signals beyond 26.5GHz and to be able to analyze them on the Keysight MXA Spectrum Analyzer.

Several instruments and components are which include the HP 83752B Synthesized Sweeper, HP 83556A mm-Wave Source Modules between 26.5-40GHz and 40-60GHz using doubler and trippler architectures, HP 8349B 2.0-20GHz amplifier, HP 11970 series harmonic mixers and OML DPL313B diplexer. Combining all these instruments along with various waveguide to coax converters mm-wave generation and detection is successfully demonstrated.

Finally, a full teardown of the mm-wave source module is presented which includes the preamplifier as well the waveguide module with very interesting design architecture.

Noise & Performance Considerations of the DPH3205 Buck-Boost DC/DC Converter Module

In this episode Shahriar investigates the noise generated from the DPH3205 Buck-Boost DC/DC Converter Module. This module is part of a family of affordable devices which can be purchased online. The particular model (DPH3205) shown in this video can be purchased from here. The Keysight S-Scope in conjunction with the N7020 power probe is used to measure the noise behavior of the circuit. It can be observed that the module produces many harmonics of noise spanning up to and beyond 1MHz.

A power operational amplifier is used in conjunction with a 4V Zener diode to produce a crude voltage follower. The PSRR of the operational amplifier can filter the noise from the DC/DC converter. This is verified by measuring the noise coming from the operational amplifier. The noise is significantly reduced. This circuit is not entirely practical and is used for demonstration purposes only.

Teardown & Repair of an Agilent 54845A 1.5GHz 8GS/s Infinium Oscilloscope

In this episode Shahriar repairs an Agilent 54845A oscilloscope with an intermittent failure. The instrument occasionally fails self-calibration and the displayed waveform shows undesired spurious activities. The teardown of the instrument reveals customized front-end section coupled into a ceramic-substrate ADC ASIC designed by Agilent. The packaged ADCs are placed in sockets. The ICs are removed and the ceramic carrier is cleaned; this resolves the intermittent problem with the channels. The architecture of the scope is also presented. The functionality of the scope is verified through self-calibration, self-test and measurement of various waveform.

Tutorial on the Theory, Design and Characterization of a CMOS Transimpedance Amplifier

In this episode, Shahriar and Shayan discuss the design and characterization of a deceptively simple CMOS inverter-based transimpedance amplifier. The the large and small signal behavior of the CMOS inverter is discussed and measured using the Keithley 2450 and 2460 source meters. The transient response is also measured using a Keysight MSO-S series oscilloscope.

The small signal gain of the circuit is calculated from small signal parameters which are extracted directly by measuring the devices I/V characteristics. The NMOS/PMOS devices used are from an ADL1105 quad-discrete transistor IC. Through the use of a shunt-shunt feedback, the CMOS amplifiers is converted to a transimpedance amplifier which is capable of amplifying the current from a photo-detector diode by a gain of 30kV/A. The feedback theory is used to calculate the gain of the amplifier. The slides for this tutorial can be downloaded here.

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