Circuits & Schematics - Measurement

The circuit uses a very inexpensive C-MOS IC that is connected to a small photodiode. Using a unique inductive feedback network, the circuit provides high sensitivity under high ambient light conditions. It is a great circuit when you want to ...

A DC load is an essential testing tool for any electronic enthusiast, especially for testing and repairing power supplies. An adjustable DC load can limit the current at any desired level, which makes it suitable to perform various tests because ...

Recently, frequent and favorite contributor Nick Cornford gave us a cool and novel acoustic-interface design for a super sub-ohmmeter capable of audibly sniffing out defects in PWBs: “Tuneful track-tracing” ( Ref. 1 ). Figure 1’s ...

A topic that has recently drawn a lot of interest (!) and no fewer than four separate design articles (!!) here in Design Ideas, is the conversion of 0 to 20 mA current sources into industrial standard 4 mA to 20 mA current loop signals. ...

A recent Design Idea (DI), “Silly simple precision 0/20 mA to 4/20 mA converter,” ( Ref. 1 ) by prolific DI contributor Stephen Woodward uses the venerable LM337 regulator in a creative configuration along with a few passive components, ...

Commercially available IR distance rangers typically handle a 3- to 30-in. detection distance. Many times, it is necessary to determine smaller distances. The circuit in Figure 1 is useful for measuring small distances to reflective surfaces. Its ...

An important figure of merit for all precision constant current sources is their active impedance. Which is to say, just how “constant” is their output held against changes in applied voltage? Frequent and expert Design Idea (DI) ...

The circuit in this Design Idea detects short-circuit faults or excess-current conditions in line-operated equipment, such as a UPS (uninterruptible power supply), across an isolation boundary. If the load current rises higher than a predetermined ...

Unless you add a measurement instrument to your computer, you have only the sound card as an analog I/O port. You can use the sound card to digitize ac analog voltages but only within a limited range. You can, however, add some signal processing ...

Another day, another dodgy device. This time, it was the continuity beeper on my second-best DMM. Being bored with just open/short indications, I pondered making something a little more informative. Perhaps it could have an input stage to amplify ...