A letter to the editor

The goal of this letter is to point out that the fastest way to weaken any society and its business model, including the IEEE and its reader-pays stance, is to lose your professional integrity

The engineers that time forgot

You and I, dear reader of IEEE Microwave Magazine, are set to become more valuable day by day. Let me see if I can paint a picture of why

Electronics: A potted history and a glimpse of the future

Keynote Speech. New Zealand has a thriving electronics industry with a long history. The renowned Kiwi ingenuity fits in well with the creative, understanding-based aspects of electronics, a discipline that is both an art and a science. However, the face of electronics is changing with the passing decades

3D-printed Acoustic Directional Couplers

Acoustic Directional Couplers permit separation of forward and reverse sound pressure waves. This separation opens the way to traceable precision acoustic reflection measurements. In order to span the audio frequency range, multiple couplers will be required, as each operates over a frequency range of slightly more than one octave. To reach 20kHz or above requires vary small, mechanically precise construction. We achieve this by 3D printing techniques. We manufactured two otherwise-identical couplers, one made with a powder-type 3D printer with photopolymer support structure, the other made with an ABS-filament thermoplastic-type 3D printer. We compare the measured acoustic performance of these two couplers. The wavelength of sound at 20 kHz is comparable to that encountered at a microwave frequency of 18 GHz. We expect to be able to fabricate couplers that reach 55 kHz where the wavelength is 6 mm, corresponding to a frequency of 50 GHz in the electromagnetic spectrum

The slot car stig: Performance and consistency of a slot car driven by a heuristic algorithm in an embedded microcontroller

We present theory and measured performance of an autonomous slot car driven by a heuristic algorithm on a typical track. The hardware consists of a PIC 8-bit single-chip microcontroller with various sensors driving a standard permanent-magnet (PM) brushed dc (BDC) motor in a mechanically-standard Scalextric platform. We present some interesting results concerning the relative difficulty of apparently-balanced lanes on a track. The car achieves optimum lap times with high consistency. Measured performance agrees with theoretical expectation. The consistency of performance allows the impact of experimental changes to be reliably assessed

Failure analysis of some Toyota Prius battery packs and potential for recovery

The Toyota Prius battery pack consists of 38 individual battery blades, each blade contains 6 NiMH cells in series. This means that each pack contains 228 NiMH cells. Each cell has the potential to fail. This report investigates the mode of failure of Prius battery packs by first analysing a number of packs in the lab, and then road testing them in a Toyota Prius. The analysis of the battery packs shows that some packs had aged “linearly”, that is in a balanced manner, such that the state of health of all blades remained similar. However, in other packs discrete blades had significantly different states of health. A pack that consists of cells that are matched in both state of health and state of charge delivers the best performance. The research also showed that the worst cell in the pack determines the overall pack performance. This was demonstrated by substituting reducedcapacity or short-circuited blades into a functioning battery pack. A vehicle with a pack consisting of 37 2400 mAh battery blades and one 1200 mAh battery blade was only able to drive 1.3 km in Electric Vehicle mode, as opposed to 2.6 km with a pack consisting of 38 2400 mAh battery blades

Identification of threshold concepts involved in early electronics: Some new methods and results

This manuscript reports the threshold concepts identified over a two-year study in early circuits and electronics courses. Some novel methods have been used to improve confidence in the identification process. We also identify some concepts, potentially threshold, that ought to have been mastered in high-school physics courses but that are often absent from student repertoires. Weak understanding of these underlying concepts may be a confusing factor for researchers in their search for threshold concepts as well as an additional source of trouble for students of electronics

Acoustic tamper detection sensor with very low false alarm rate

We describe a device designed to detect interference (vandalism or tampering) by acoustic means. The design employs both a piezoelectric vibration transducer and a common microphone in a novel mechanical arrangement. In contrast to conventional acoustic sensors that simply respond to vibrations above a threshold, this design analyses the outputs of the two to trigger an alarm. The method confers a near-zero susceptibility to triggering by external loud noises. No complex calculations are required so that only a low-cost, embedded microcontroller is required and the whole sensor can be very cheap. Extreme sensitivity can be achieved with little risk of false alarms

Compact nonlinear model of an implantable electrode array for spinal cord stimulation (SCS)

We describe the construction of a model of the electrode-electrolyte interface and surrounding electrolyte in the case of a platinum-electrode array intended for spinal-cord stimulation (SCS) application. We show that a finite, two dimensional, resistor array provides a satisfactory model of the bulk electrolyte, and we identify the complexity required of that resistor array. The electrode-electrolyte interface is modelled in a fashion suitable for commonly-available, compact simulators using a nonlinear extension of the model of Franks et al. that incorporates diodes and a memristor. The electrode-electrolyte interface model accounts for the nonlinear current-overpotential characteristic and diffusion-limiting effects. We characterise a commercial, implantable, electrode array, fit the model to it, and show that the model successfully predicts subtle operational characteristics

Group-delay measurement of frequency-converting devices using a comb generator

We propose a new method for the measurement of (group) delay from the radio-frequency (RF) input to the intermediate-frequency (IF) output of a mixer or a receiver. The method is particularly convenient for measuring the change in group delay with the local-oscillator (LO) tuning frequency of the receiver since the method does not require access to, or even knowledge of, the LO signal. The method employs a calibrated comb (impulse) generator. Other required equipment is limited to a reference signal generator and a digitizer of modest bandwidth, allowing the measurement to rely on a low-frequency generator and an oscilloscope. Simulated and measured data are presented to verify the approach