Articles and news - 7

A while ago, I needed (or wanted) a pocket-sized audio sine-wave generator: simple, stable, repeatable, single-gang control pot, 9 V battery-powered. A “squashed tri-wave” approach looked appropriate...

The control circuit isenses a given load and automatically soft-starts the load by synchronously adjusting the power to that load. You can also manually adjust the power delivered to the load by controlling the phase angle of the line voltage across the load...

To control their brightness, LEDs need a constant current; this can be done with a resistor placed in series with the LED string. Both the LED-string voltage and the supply voltage can vary, so a dedicated LED driver is a must to guarantee the current accuracy...

Intrinsically capacitive transducers and other high-impedance signal sources usually require ac coupling and a buffer amplifier to condition the signal for further processing. Buffers take many forms...

Digital gates are fundamentally analog in nature. They use transistors. Sure, these transistors are operated at their conduction extremes (which is why they are called “digital”), but during the logic state transition they're pure analog...

This Design Idea describes a new class of logic gates, which we have named resistor-FET-logic, aka “RFL.”...

A classic analog application is the full-wave precision rectifier (absolute value) function. Many variations exist on this theme, each with its own supposed (often rather minor and sometimes downright dubious) advantages compared to competing topologies...

Brushless DC motors transform electrical power into mechanical power. However, there’s no such thing as a perfect motor; there are always losses in the transformation...

It was a no brainer – at first. Circa 1985 equipment still in use by telcos, the DUT was a remote-operated twisted-pair telephone cable analyzer. We had extensively reverse-engineered and repaired several of these a couple years ago, the OEM was defunct...

While choosing an op-amp buffer, some sources of negative supply were considered, because the buffer op-amp had to provide true zero voltage on its output...