Monarch Instrument Stroboscopes
In 1982, Monarch Instrument was established to manufacture and market the first microprocessor-based portable tachometers. With the growth of this product line, and the introduction of the Nova-Strobe Series of portable stroboscopes, Monarch rapidly became the world’s largest supplier of rotational speed measuring instrumentation and stroboscopic inspection equipment.
The company’s design philiosophy — “Innovation in Instrumentation” — has led it through the development of numerous other devices, including the Palm Strobe, with its removable, rechargeable battery pack, and the Phaser-Strobe, with its outstanding range of features and flash rate up to 50,000 per minute. These instruments, along with the updated Nova-Strobe models, serve as powerful diagnostic tools used in maintenance, quality and process control, and R & D.
Specifying and selecting the Monarch strobe for your application is based on a few simple questions.
First, is your only requirement to check RPM? If so, you may wish to consider one of Monarch’s tachometers instead of a stroboscope. If you need slow motion or stop action visual inspection of rotating, linear, or reciprocating objects, a stroboscope is indicated.
Second, do you need cord-free use? If so, one of the rechargeable models will be the obvious choice. If not, you may still prefer the utility of a battery-powered unit due to its ease of use. Generally, we would recommend the AC (line) powered units for permanent or semi-permanent use in one process location, and the battery powered units for use in multiple locations, even if AC power is readily available at all of them. Remember that the Phaser-Strobe pbx can be run from batteries, or directly from AC through its recharger.
Third, what is the maximum flash rate you will require? The models shown below have maximum flash rates varying from 10,000 to 50,000 FPM (flashes per minute). The minimum rate will not usually be a factor, as human perception is not readily fooled into “freeze mode” at flash rates of under about 300 per minute.
Fourth, how bright an output do you need from the flash? The 13 watt L-1903 xenon lamp offers outstanding output, which is a real benefit in brightly lit environments, while the 7.9 watt L-1905 xenon lamp used in the Palm Strobe will be adequate for many applications.
Fifth, will you need external input or output triggering? If so, be sure to choose one of the models with TTL compatible 1/8" phone plug inputs and outputs. These options would often be used to “daisy chain” a number of strobes for larger area illumination, or to allow control of flash rate from a remote sensor, thus ensuring exact synchronization from signals whose frequency may change.
Finally, the ability to rapidly double or halve the flash rate, show slow motion, phase shift, retain memory settings, operate in a moist or dirty environment (the battery powered Nova-Strobes and Phaser-Strobe can be supplied with a clear vinyl cover, which will keep foreign material from affecting performance), and the need for a certificate of calibration traceable to N.I.S.T. may affect your final choice.
The Monarch family of stroboscopes offers a wide array of features to suit almost any application. Please review the following table, which should help you narrow your choice to the one most appropriate model. Click to view (Will open a new window).
NOTES: (1) "x" = yes; "-" = no; (2) Accomodates 115Vac at 60 Hz or 230Vac at 50 Hz, and includes adaptor plugs for U.S., U.K., Australian or Euro receptacles; (3) rapid doubling and halving of the flash rate facilitates determination of the fundamental operating frequency of the process you wish to evaluate; (4) Using optional external trigger.
Freezing Action: Allowing the human eye to see “stopped action” is the primary use for a stroboscope. This simple technique can be used in a myriad of applications, including product inspection and process control in printing, coating, rotary diecutting, textile processing and finishing, papermaking, embossing, and other high-speed operations. Maintenance diagnostics can also be performed without machine shutdown.
To freeze action, simply start at the maximum flash rate, and gradually slow the flash until you reach a speed at which the illuminated image stops moving. If you are observing a fixed-rate process, no further adjustment will be necessary, though you may wish to halve the flash rate progressively to save on flash life. In the example of a printing press, halving the flash rate will result in illuminating only every other impression; halving it again would show only every fourth impression, etc. Your inspection needs and image quality will determine the optimal flash rate for each application.
Determining Fundamental Operating Frequency and RPM Measurement: The method in the preceding paragraph describes how to determine the fundamental operating frequency for any process which is slower than the maximum flash rate of the instrument. This operating frequency, measured in flashes per minute, is equivalent to the RPM of a rotating object. Note that the object being measured should be visible for all 360 degrees of rotation, and that the rotating object must have some distinguishing feature or mark on which to focus. If the process runs faster than the strobe's maximum flash rate, an analysis of harmonics, as explained in the Monarch operating manuals, will be required.
Phase Shifting: Internal phase shifting allows the user to visually shift a reference mark to a different viewing position. This technique is useful when the reference mark is hidden or obstructed. Moving the reference mark is accomplished via a jog button which relocates the image.
External phase shifting allows the tracking of variable speed machinery. External phase shift also allows a fixed delay in rotational degrees or time, with the stroboscope flash being delayed from an external trigger signal. This feature is used to look at an instant of a cyclical operation that differs from the timing (location) of the trigger signal. For instance, you may wish to observe an engine at bottom dead center (BDC — valves closed), but need to use a mark at top dead center as a trigger. You would simply shift the phase 180 degrees through the electronics of the strobe.