Dave walks around the Electronex 2014 electronics exhibition at the Australian Technology Park, after hours when no one is there, and takes a peek at every stand.

**Electronex 2014 – Walkaround -** [Link]

A tutorial on feedback resistors in DC-DC converters and how to build a high current adjustable power supply using an LM2678.

**Build a 2.5V to 14V 3A adjustable power supply! -** [Link]

What’s inside a dial-in pacemaker monitor system?

**EEVblog #656 – Pacemaker Monitor Teardown -** [Link]

by mjlorton:

In this series of video I want to take a look at what the industry has to offer in terms of DC Power and Energy Measurement Meters / Analyzers (Analysers). There seems to be a distinct lack of affordable instrumentation in this area.

**DC Power and Energy Measurement Meters – Pt 1 -** [Link]

This video describes how a classic double-balanced diode-ring mixer operates. Very basic mixer theory is quickly reviewed, which describes how the sum and difference of the LO (local oscillator) and RF (Radio Frequency) inputs are generated at the IF (intermediate frequency) output. It is also noted that the sum and differences of the harmonics of the LO and RF are also present at the IF output. Math waveforms on the oscilloscope are used to illustrate the operation of the mixer, and the actual waveforms from the mixer are compared to the math waveforms and the differences are discussed. A detailed description of the operation of the mixer is presented, including the switching action of the diodes. Finally, the frequency components are are expected from the mixer are shown on the spectrum analyzer.

**How a Diode Ring Mixer works | Mixer operation theory and measurement -** [Link]

Dave explains a big trap in high frequency measurement with your oscilloscope. Based on a viewer request, Dave demonstrates how to incorrectly and then correctly measure the signal output level over frequency of your function generator using your oscilloscope. Some whiteboard transmission line theory is thrown in as well.

**EEVblog #652 – Oscilloscope & Function Generator Measurement Trap -** [Link]

TheSignalPathBlog writes:

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 from The Signal Path website.

**Theory, Design and Characterization of Delta-Sigma Analog to Digital Converters -** [Link]

by limpkin @ limpkin.fr:

During the month of July I was visiting Beijing and had an extra 10 days to spare. What to do? Well it took me less than a few minutes to decide to go the wonderful city that is Shenzhen…

**Video Series – Touring Factories in Shenzhen -** [Link]