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, ...
This Design Idea (DI) offers an alternative solution for an application borrowed from frequent DI contributor R. Jayapal, presented in: “A 0-20 mA source current to 4-20 mA loop current converter” ( Ref. 1 ). It converts a 0/20 mA ...
A 4 to 20 mA loop current is a popular terminology with Instrumentation/Electronics engineers in process industries. Field transmitters like pressure, temperature, flow, etc., give out 4 to 20 mA current signals corresponding to the respective ...
I recently published a simple design ( Ref. 1 ) for a platinum resistance detector (PRTD) 4 to 20 mA transmitter circuit, illustrated in Figure 1. Figure 1. The PRTD 4 to 20 mA loop transmitter with constant current PRTD excitation that relies on ...
Accurate, inexpensive, and mature platinum resistance temperature detectors (PRTDs) with an operating range extending from the cryogenic to the incendiary are a gold (no! platinum! ) standard for temperature measurement. Similarly, the 4 to 20 mA ...
In the early days of personal computers, incorporation of one or two (or more) RS-232 serial ports as general purpose I/O adaptors was common practice. Recently, this “vintage” standard has been largely replaced (after all, it is 64 ...
A high-side current-sense amplifier, IC 1 , offers a simple method of combining low-speed clocks or other signals with dc power in cables between subsystems (Figure 1). Designed for monitoring charge and discharge current in secondary batteries, IC ...
The 0- to 20-mA current loop is a reliable means of data communication in industrial applications. These circuits use a precision shunt in the receiver to convert the current signal into a voltage signal. Accidentally connecting the precision ...
Systems using line receivers for differential input signals require an adequate self-test capability. Using an LM339 (a quad differential comparator), you can provide this capability by constructing the configuration shown in the Figure 1. ...