In this episode Shahriar takes a close look at an EG&G DSP-Based Lock-In Amplifier. This instrument provides excellent sensitivity for both voltage and current inputs and is based on a fully digital architecture. The instrument’s LCD screen is dim and unreadable. Furthermore, a few lines are missing from the LCD pointing to a failed zebra strip.
The instrument’s block diagram is examined and explained. The teardown reveals the structure of the LCD screen, front-end blocks and internal PLL. The CCFL back-light inverter is located and replaced with a low-voltage DC-DC converter for use with an LED strip. The instrument’s functionality is verified through a few experiments including measuring the 3dB bandwidth of an RC filter as well as measuring the photo-current induced in an LED using a synchronized infrared light source.
In this episode Shahriar reviews his new 3D Printer Sindoh 3DWOX 1. This printer offers several attractive features. The fully enclosed design is quiet and equipped with a HEPA filter. The unit is also equipped with a webcam and internal lighting. The printer has several automatic capabilities such as auto filament load from a cartridge, bed-leveling and print parameter optimization. The printer is also completely compatible with off-the-shelf filaments.
This comprehensive review is organized as follows:
01:57 – Model comparison and Sindoh website
02:26 – Printer design and overview
04:16 – Internal construction and features
07:03 – Cartridge design and filament auto-load
09:31 – Printing bed auto-leveling procedure
11:53 – 3DWOX desktop software overview and features
16:32 – First print example and procedure
17:53 – Mobile app and remote camera monitoring capability
18:51 – Print example: Objects with extreme aspect ratios
22:03 – Print example: Objects with moving parts and joints
25:27 – Print example: Objects with many holes and thin features
28:24 – Print example: Large objects with >24 hour print time
30:12 – Analyzing internal print features using an X-ray machine
32:46 – Printing microwave and mm-wave components and filters
38:27 – Concluding remarks
In this episode Shahriar repairs an Agilent N9020A MAX Spectrum Analyzer. The instrument is well equipped with real-time capability and direct I/Q input ports on the front panel. The instrument does not show the correct signal levels and fails internal calibration.
After a brief teardown, the block diagram of the instrument is carefully examined for potential failure points. It is determined that front-end switch and mechanical attenuator is likely faulty. Teardown of the unit reveals significant damage to the attenuator due to some high-power at the input. Unfortunately, this also implies that the front-end RF selector and pre-amplifier modules are also damaged. In the second repair video, the front-end module is disassembled and damage to the dies can be observed.
Luckily, a relatively inexpensive front-end (SSLAM) unit is sourced from eBay and the repair is completed. The performance of the unit is verified after the repair and the front-end I/Q input functionality is demonstrated.
In this episode Shahriar presents a meticulously prepared set of educational lab kits on Power Conversion by Texas Instruments. These kits include Buck, Boost, LDO and Buck-Boost power conversion courses complete with a beautiful set of lab instructions and PCBs. Each kit describes up to 7 different exercises which demonstrates various aspects of power conversion characterization and design challenge.
In particular the Buck Lab kit is examined. The PCB is populated with two different Buck DC-DC converters which are carefully described in the lab kit. The first experiment of the lab kit is performed which involves measuring system efficiency under various load conditions and switching frequency. The inductor current, MOSFET switching voltage and output waveform are examined on the oscilloscope.
In this episode Shahriar demonstrates the principle of operation of a purely passive Weston watt-meter manufactured in the 1950’s in Newark, NJ, USA. This watt-meter makes no use of active devices (tube or solid-state) and yet is able to measure real-power both at DC and AC.
The teardown of the unit shows the construction of two coils interacting to advance the needle on the display. One coil produces a magnetic flux proportional to the current input and the other coil produces a magnetic flux propositional to the voltage. The interaction of the flux moves the needle proportional to the total power which is the product of current and voltage. The instrument is then used in conjunction with a power supply and electronic DC load to verify its functionality.
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 reviews, tutorials and repair videos are posted regularly.