In the first part ( Ref. 1 ) of this Design Idea, we saw how a cheap op-amp can give remarkably precise readings from an RTD. We also found that it was a false economy, owing to incurable thermal drift. This concluding part fixes that problem by ...
In process industries, field contacts from pressure, temperature, flow switches, limit switches, push buttons, etc., are read by programmable logic controllers and/or distributed control systems (PLC/DCS) through digital input modules. They are ...
For decades, I’ve had a fascination with voltage-to-frequency converters and the 555 analog timer chip, and therefore a double obsession with VFCs based on the 555. In fact, my first Design Ideas (DI) submission (in 1974) was for a 555 VFC. ...
This project is an ultrasonic range finder built using the RP2040 Zero board and a 3.2-inch TFT display. It utilizes the RCWL-1655 sensor, which operates similarly to the popular HC-SR04, to measure distances ranging from 20 cm to 300 cm. The ...
This two-part Design Idea (DI) follows on from a couple of previous articles relating to 100-Ω platinum resistance temperature detectors (Pt100 RTDs). The first of those (which we’ll call Ref 1 ) used a simple current-driven bridge to give an ...
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 ...
My recent DI contribution (Another silly simple precision 0/20 mA to 4/20 mA converter, Ref. 1 ) used the LM337 regulator in a novel circuit arrangement to translate an input 0-20 mA current source into a 4-20 mA two-wire transmitter current loop ...
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. ...