AC-in, DC-out Baristors

In industrial and consumer electronics, the use of thyristors and triacs is known to corrupt the AC grid voltage to a degree due to harmonics, noise, bursts and transients being superimposed on what you thought was a clean sinewave from the power outlet. A newly developed composite electronic device called the baristor can help to keep the line voltage clean yet offer good regulating properties. This article describes the baristor’s functionality as well as three practical AC-in, DC-out incarnations, on circuit boards.

Inherent to their elementary design, thyristors and triacs acting as load switches are characterized by high cathode-anode voltage drop in the ‘open’ state, and “much left to desire” in terms their switching performance. Consequently these ‘SCR’ devices are prone to high power dissipation, occasionally causing overheating and eventual failure of the complete semiconductor device. At the same time, the very heating of a traditional thyristor equals electric power wasted, leading to considerable losses when scaled up to mass industrial and household use across the globe. High time for a ‘greener’ device, and here it is.

Developing a frequency divider with an adjustable division factor is often said to be a complex assignment. In response to that “challenge”, we developed a circuit that although rudimentary, still allows you to divide the frequency of a digital signal by a factor n.

In the past, rheostats (today also called potentiometers) were connected in series with a load to control the current owing through the load. Although simple, this technique has some disadvantages.

Complex electrical wiring is required if a single load like hallway or corridor lighting is to be switched on and off by any one of a large number of switches. Here we propose a workaround using a DIY thyristor.

This night light has two power sources: a solar cell with a peak output voltage of about 6 V, and a Li-Ion cell with a voltage between 3.7 V and 4.2 V. Three (of four) electronic switches in a 74HC4066N (IC1) control the device operation. The battery charging rate as well as the intensity of the LEDs may be adjusted.

In radios designed for long distance communication, a notch filter is used to suppress or hopefully wipe out noise, whistles, buzzes, static, chirps, woodpeckers and what have you that persistently degrade the wanted signal. In this article we cover simple LC and RC notch filters for use in the radio’s intermediate frequency (IF) section.