Circuits & Schematics

Ordinary bipolar junction transistors can sometimes be precision sensors. When you think of precision components, you usually don’t (and probably shouldn’t) think of general-purpose bipolar junction transistors. Are GP BJTs cheap and ...

The circuit is powered for years by a single 3 volt lithium battery. It sounds an alarm when the temperature exceeds a certain point. With some minor changes the circuit could also be configured for an under temperature (freeze) alarm. The circuit ...

A subtle change to a standard circuit can enhance its usefulness and even save a resistor. If there were a prize for the most trivial Design Idea (DI) of the year, this one would likely be high on the shortlist (if not at the top). Most DIs involve ...

Simple analog circuits manage multi-PSU powerup and shutdown sequences In projects containing digital and/or analog circuits, multiple power supplies are used, generally 5 V DC for digital circuits and 15 V DC for analog circuits. Some projects ...

This circuit uses a flat piezoelectric wafer, glued inside a plastic box, as a finger tap sensor. With each tap of a finger to the box holding the wafer, the circuit turns on and off AC or DC power to an external device. The circuit is powered by a ...

Story Infrared remote controllers are everywhere around us. The majority of home appliances are controlled using infrared remote controls. In this article, we learn to build a device that can decode (almost) any IR remote control and use the ...

Op amps tend to make analog design easy. Maybe sometimes too easy? Don’t get me wrong. I like operational amplifiers. Some of my best friends are op amps. They embrace such a wide range of varied capabilities, including low noise, high power, ...

Class D amplifier with a good performance and better sound quality. We can call it a Class D with Class A specs. Story I am a fan of audio technology as it is cleared from most of my articles. I always try some new ICs or audio related things here. ...

Combining an accurate temperature sensor with a standard digital multimeter can make an inexpensive, accurate, and useful thermometer. A recent Design Idea, BJT is accurate sensor for absolute temperature in Kelvin and Rankine ( Ref. 1 ), was based ...

Simple math implemented in a (very) simple circuit. What’s not to like? A very cool (also warm!) property of the base-emitter junction of (most) small signal BJTs is the ΔV BE temperature-sensing effect. ΔV BE temperature ...