Circuits & Schematics - Analogue Design

Recently (5/21/25), I published a Design Idea (DI) describing a bidirectional current mirror using just two transistors and a diode, “A two-way mirror current mirror that is” ( Ref. 1 ). That circuit works well in some applications, ...

In the first part ( Ref. 1 ) of this Design Idea (DI), we saw how to use the TDA7052A (or similar) power amp to build a minimalist siren-type power oscillator, and also, having looked at that device’s distortion characteristics under various ...

When audio power amplifiers oscillate, the result is often smoke, perhaps with a well-cooked PCB and a side order of fried tweeter. This two-part Design Idea (DI) shows some interesting ways of (mis-)using a common power amp to produce deliberate ...

Designing an analog circuit can be a frustrating experience, as noted by Nick Cornford in his Design Idea (DI), “DIY RTD for a DMM” ( Ref. 1 ). With a fortnight’s struggle, I completed the design of 4 mA to 20 mA, two-wire ...

The TL431 has been around for nearly 50 years. During those decades, while primarily marketed as a precision adjustable shunt regulator, this legacy device also found its way into alternative applications. These include voltage comparators, audio ...

One classic set you’ll see in most гvintage mystery movies is an interrogation room with a “two-way” mirror in one wall. This cool gadget lets the witnesses see the suspects from another room while the suspects can see only ...

In Part 1 of this Design Idea [ 1 ], we saw how a standard electret microphone capsule can be persuaded to detect infrasonic signals down to a fraction of a Hertz by adding some fairly simple equalization. In this second and concluding part, we ...

Electrets aren’t only used as audio pickups. For decades, they have been employed in security systems to detect unexpected changes of air pressure within rooms, while more recently they can be found in vapes as suck-sensors (or, more ...

In April 2012, EDN published a circuit by John Fattaruso ( Ref. 1 ) that lets you quickly measure the drain-source saturation current and the pinch-off voltage of both an N-JFET and a P-JFET. The pinch-off voltage (V P ) is measured by inserting a ...

Figure 1’s negative constant current source has been a textbook application for the LM337 regulator forever (or thereabouts). It precisely maintains a constant output current (I OUT ) by forcing the OUTPUT pin to be the negative V ADJ ...