The Type 1531-AB Strobotac is a versatile flashing light source that is used to measure the speed of rotating objects or to produce the optical effect of stopping or slowing down high-speed motion for observation, analysis, or high-speed photography. When the approximate speed of a motor is known, an operator can accurately measure the speed of motors quickly and with confidence.

POWER switch. Turns power ON and OFF

R.P.M. control. Controls flashing rate of light by rotating fluted rim; the dial is calibrated directly in r/m (r.p.m.).

RANGE switch. Selects any of three r/m ranges (internal oscillator)

There are three external input positions.

CALIBRATION indicator light. Indicates correct setting of calibration adjustments and calibrates R.P.M. dial to power line frequency

HIGH CAL and LOW CAL adjustment screws

Calibration adjustments for calibrating R.P.M. dial

OUTPUT trigger jack. Trigger pulse is available at this jack for triggering Strobotac Types 1531 and 1538.

INPUT jack. Used for connecting Strobotac to external synchronizing signal from electrical device or mechanical contactor

Reflector lamp assembly. Produces and aims flashing light

Power cord. Permanently attached 6-foot power cord

Holder pin. Holds the plug end of the power cord when the Strobotac is to be stored in its case.

Strobotac setup and preparation

Set the Strobotac on a flat surface so it rests on its rubber feet. Unlock the case by sliding the slide locks (one on each side) away from the handle.

Use the palm of one hand to push the handle down as far as possible. With the other hand, swing the Strobotac to the desired position. Slowly release the handle to lower the Strobotac onto the rubber gasket.

Before plugging the power cord into the receptacle, ensure that the power matches the data on the plate next to the power cord on the panel.

The power plug has three terminals; two are for power, one is a ground. The third terminal must be grounded.

Plug the Strobotac into the power supply, pivot the reflector lamp to an upright position, and turn the power switch to the ON position.

Position the Strobotac. The light beam can be pointed in almost any direction by the swivel arm and the rotating reflector.

Calibrating the Strobotac

Allow the Strobotac to warm up for 10 minutes. Refer to the calibration chart in the cover of the Strobotac for the HIGH CAL and LOW CAL R.P.M. dial settings indicated for the power line frequency being used.

Turn the RANGE switch to the range required to make these settings. Set the R.P.M. dial to the exact HIGH CAL R.P.M. dial setting called for in the calibration chart.

The CALIBRATION light does not have to be completely off.

Adjust the HIGH CAL screw until the on-off pattern of the neon CALIBRATION indicator light stops or nearly stops. Set the R.P.M. dial at the exact LOW CAL R.P.M. dial setting indicated on the calibration chart.

The CALIBRATION light does not have to be completely off.

Adjust the LOW CAL screw until the on-off pattern of the neon CALIBRATION light stops or nearly stops. Return the R.P.M. dial to the HIGH CAL R.P.M. dial setting. If the neon CALIBRATION light blinks on and off too quickly, repeat above steps.

The R.P.M. dial is now calibrated to within one percent on all scales.

Operating the Strobotac

Never leave the Strobotac unattended while in use. Since the Strobotac makes a moving object appear to be standing still, someone could be injured by a "stationary" object.

Because a motor may run at a slightly different speed than nameplate data indicates, set the R.P.M. dial at a higher flashing rate than the speed of the motor.

Select the range needed on the range selector switch. The speed limits for each range are marked near the appropriate window.

Take care to observe that the image (see below) reflected by the light is truly stationary.

Slowly reduce the flashing rate until the first single image is observed. At this point, the flashing rate of the Strobotac will be equal to the speed of the motor and can be read directly from the R.P.M. dial.

Note the indicated motor r/m and enter the reading in the appropriate section of the motor data sheet (electrical).

When using low or midspeed ranges, switch to the next higher range without moving the R.P.M. dial setting. Check if the Strobotac is flashing at the fundamental speed of the object being measured.

Since the ratio between ranges is six to one, six images will appear at the next higher range if the Strobotac has been set to the fundamental speed. Oddly shaped objects are usually easy to measure, but round objects, such as motor shafts, must be marked with a piece of tape or a grease pencil to provide a visible reference point.

Securing the Strobotac

Secure the Strobotac after use. Push the reflector down against the panel. Keep the reflector cover up to avoid damage to the reflector.

Turn the RANGE switch to the 4,000 to 25,000 R.P.M. scale. Wrap the power cord clockwise around the RANGE switch and reflector. Secure the power cord plug by sliding the ground terminal of the plug onto the holder pin.

Lift the Strobotac until it is free to pivot on the handle. Lower it into the case.

Unless the locks are in place, the Strobotac case will fall open.