Archive for General

Tutorial, Teardown & Experiments with Stanford Research SR530 Lock-in Amplifier

In this episode Shahriar goes over the operation and principle theory behind Lock-in Amplifiers. The SRS SR530 is one of the most iconic lock-in amplifiers ever made and since it offers two channels it can be used to perform very interesting experiments across many domains. After reviewing the block diagram and equations governing the theory of operation, a brief instrument teardown is presented.

Two unique and interesting experiments are also presented. In the first experiment the instrument is used to measure the speed of light. This is accomplished by measuring the wavelength of sound at 20kHz using a pair of speakers and a function generator. The distance between the speakers can be carefully adjusted and the relative signal strength from each lock-in channel is measured and thus the wavelength can also be measured.

In the second experiment the sensitivity of a red LED to blue laser light is measured. Due to the semiconductor composition of the red LED as well as its red plastic casing, the responsibility of the LED to blue light is extremely low. A chopper is therefore used to lock the light to the lock-in amplifier’s reference input. The measured induced current is measured down to very low optical level in the order of hundreds of fempto (10^-15) amps.

Overview of the Tektronix MSO58 8-Channel 6.25GS/s 2GHz Mixed-Signal Oscilloscope

In this short episode Shahriar demonstrates an overview of the new Tektronix MSO58 8-Channel 6.25GS/s 2GHz Mixed-Signal Oscilloscope with up to 64-Bits of digital channels. The scope features independent ADC, data acquisition and memory per channel as well as FlexChannel architecture which allows each channel to act as either a 2GHz analog channel or an 8-Bit digital channel. The scope also features a brand new GUI interface on an HD 15.6″ display with significant performance enhancement and touch interface optimizations. A full review of the instrument will be provided in the future.

The Signal Path Giveaway & Q/A Request (March 2017)

In this short episode Shahriar shows a few items to give away! Please leave a comment and a person at random will be chosen. There will also be a Q/A session sometime in the future, please also leave your questions in the comment section.

The winners of the draw will be notified at a later date.

The Future of The Signal Path, Patreon & Q/A

Since the creation of The Signal Path video blog in May of 2011 I have focused on producing the type content which is either difficult to find or difficult to learn. Despite being the foundation of human communication, RF and microwave electronics often seem like magic and my goal has been to demystify these concepts. The Signal Path blog provides a rich depth and breadth of electrical engineering topics and experiments. Equipment reviews and repairs are always accompanied with research and industry relevant experiments and tutorials. The aim of The Signal Path is to provide free education to everyone across the world, possibly the greatest gift from a human to another.

Any support you offer to The Signal Path will be put back into lab maintenance, improving the quality and frequency of video production and acquiring components to further diversify content production. As of August 2016, The Signal Path has produced over 66 hour of original material.

On behalf of all viewers from around the world I want to thank you for supporting The Signal Path.

Shahriar Shahramian, Ph.D. Owner & Host
The Signal Path

Tutorial and Experiments with ESP8266 SoC, Blynk App, Arduino and Internet of Things (IoT)

In this episode Shahriar explores the functionality of the popular ESP8266 SoC chip. This IC incorporates a full ISM radio as well as the physical/MAC layer for 802.11b/g/n network communication. Furthermore it includes a uC core for code execution making it a low-cost candidate for Internet of Thing applications. This video uses a Sparkfun Thing evaluation board which also includes a LiPo batter charger, voltage regular, flash memory and all the I/O pins which are accessible to the user. The block diagram of the ESP8266 is reviewed as well as the schematic of the complete Sparkfun Thing board.

By using an Arduino library and the Blynk iOS application, a cell phone and the ESP8266 can simultaneously communicate with a server running the Blynk application and transfer data between the application and the module. In this demo various components such as NeoPixel (WS2812), OneWire temperature sensor and battery monitoring functionality are implemented. The code is available here.

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