Circuits & Schematics - Measurement - 14

By combining the responses of AD590 temperature sensor and a HS1101 humidity sensor, you can generate a single TTL-level signal containing information from both sensors (Figure 1). This design uses a 74HC123 monostable multivibrator, IC 1 , to form ...

This self-heated constant-temperature-delta transistor anemometer is cheap, rugged, and sensitive. It relies on the relationship between airspeed (A F ) and thermal impedance (Z T = C/W) of a heated air flow sensor as shown in the formula below for ...

In some applications of capacitive sensors, the instrument’s front end must be small enough to fit into a narrow space. Figure 1 shows a precision capacitive-sensor interface for such use. The square-wave output from a low-voltage 555 timer, ...

This Design Idea builds on a previous one ( Reference 1 ) to realize a precision peak detector with a bandwidth of 15 to 30 MHz or more, depending on the maximum input-signal level of your application. The crucial feature of this Design Idea is an ...

Amplification of sub-picoamp signal currents is always a design challenge, especially when gain adjustment is required that spans multiple decades. A straightforward approach to the design task would normally involve potentiometers and teraohm ...

Before running a formal test with multiple resistance temperature detector (RTD) sensors, it is often necessary to calibrate and debug a data-acquisition system to verify basic functionality. The brute-force approach would be to wire all the ...

A 4- to 20-mA current loop consists of a power source and a current-measuring device at the control end and a field transmitter that senses process-variable information, such as temperature or pressure, and converts it to a current (Figure 1). Most ...

You can remotely measure temperature using a 4- to 20-mA current loop as long as 4000 feet and a battery-powered, white-light LED driver. You usually configure this equipment to provide a programmable, constant current to an LED from a battery ...

Among the many methods available for air flow detection, self-heated thermal flow sensors are simple, cheap, rugged, and sensitive. They rely on the relationship between airspeed (V F ) and thermal impedance (Z T = C/W) of a heated sensor as shown ...

Passive current shunts for measuring the value of current flowing through a relatively small-value resistor often have a full-scale voltage drop of 60 mV for higher-power equipment and 200 mV for electronic instruments. Similarly, simple ...