Circuits & Schematics

The iconic LM2917 tackles frequency-to-current conversion with (very) few externals. Almost exactly 50 years ago in June 1976, to be precise National Semiconductor introduced the LM29x7 series, offering deceptively simple monolithic solutions to a ...

There are many applications when a remote switch’s on/off status needs to be monitored. Reed relay sensors, toggle control switches and security alarms contacts are just a few examples. Routing a switch directly to a computer system hundreds ...

A self-heated Darlington transistor pair makes a simple, sensitive, and sturdy airflow sensor. But first an annoying non-linearity needs unbending. If you take a self-heated transistor in a TO-92 package and force it to hold a constant temperature ...

Converting frequency signals to loop current signals creates an economical result for process industry applications. Process industry applications commonly employ multiple motors. Their speeds are monitored by tachometers using magnetic pickups ...

A linearized output is a useful elaboration of a capacitive sensor design. But what if the circuit is located a significant distance from the control electronics? Recently, Design Ideas included a circuit ( Ref. 1 ) that comprised a simple analog ...

This page provides a detailed explanation of how the modified cascode light receiver circuit operates. The cascode technique in conjunction with an inductive load provides very high current to voltage conversion as well as very high speed. Upper ...

An only slightly less simple followup circuit also ratios sensor capacitance to a reference capacitor to measure micrometers this time linearly. A few weeks ago, Design Ideas published a simple circuit of mine that provides an analog interface to ...

The circuit shown in Figure 1 is a complete microphone signal conditioning system based on a single SSM2166 integrated circuit. Designed primarily for voiceband applications, this integrated circuit provides amplification, RMS detection, limiting, ...

Here’s a neat and novel way of using a long-tailed pair to drive not just two but three LEDs. As everyone knows, rainbows always have pots of gold at their ends. This Design Idea reverses that, starting with a pot (no gold, alas) and ending ...

Circuits for converting 4 to 20 mA analog current loop signals to 0 to 20 mA may be hot topics, but hot implementations of those circuits are not. Circuit designs for conversion of 4 to 20 mA analog current loop signals, which are ubiquitous in ...