Tachometer Measurements

A tachometer is an instrument that measures the rate of rotation on a gasoline engine, electric motor, disk drive, or other spinning mechanism. The reading is usually displayed as revolutions per minute (RPM) in either analog or digital format. (more…)

analog synchroscope

What is a Synchroscope?

For two AC power systems to be interconnected (paralleled), they must be synchronized. This means they must be operating at the same voltage, the same frequency, and the same phase angle. Only when all three parameters match is it safe to connect the two systems. Paralleling two unsynchronized AC systems will cause a sudden current surge and mechanical stress on rotating equipment. This can disturb or severely damage one or both systems. (more…)

Frequency Meter

Line Frequency Measurements

Frequency is an important parameter for an ac waveform. The frequency, in Hertz, is defined as the number of cycles per second. It can also be expressed as 1/T, where T is the time for one cycle. One period is the duration of one complete cycle, in seconds. (more…)


Bluetooth for Instrumentation

Most of us are familiar with Bluetooth as the connection from a cell phone to wireless earbuds or a remote speaker. This low-power communication protocol is simple to set up and use. It operates in the globally unlicensed industrial, scientific and medical (ISM) band from 2.40-2.48 GHz. (more…)

4-20mA Loop

Reducing Burden in a 4-20mA Loop

Current loops are a popular method for monitoring equipment and processes in industrial environments. Some of their advantages were discussed in an earlier posting. Additional advantages of the 4-20mA loop are:
– easy detection of an open loop, since the signal zero is represented by 4mA.
– the offset zero allows use of loop-powered devices that don’t require a separate power connection. (more…)