GenRad 1538-A Stroboscope

  • The highest flashing rates for a stroboscope-up to 150,000 Flashes per mn,
  • Flash duration from 0.5 μs to 3.0 μs for clear, crisp images.
  • Accessory energy-storage capacitor 1538-P4 for very short single flashes.
  • High accuracy stroboscope — rpm measurements can be made to ± 1%
  • 0.5 μs— "stops" rapid motion and permits ultra-high-speed photography.
  • Can be battery operated
  • Convenience — small Flip-Tilt case and swivel-mounted lamp.
Priced at
The GenRad 1538 Stroboscope is a more versatile instrument then the GenRad 1531-AB Strobotac. In addition to providing a much higher maximum flashing rate, the GenRad 1538-A Stroboscope also incorporates many features and user conveniences. It can be operated from a power line, or, if there is no power outlet nearby, from the 1538-P3 rechargeable battery pack.
The 1538-P2, accessory extension lamp is useful in illuminating hard-to-reach areas.
The 1538 stroboscope is ideally suited for applications requiring a high light intensity. With the GenRad 1538-P4 Energy-Storage Capacitor, it is possible to produce very short flashes of light of 44 millionbeam candles at one meter distance.


  • 1. Observation and speed measurement of gears,cams, linkages, shuttles, spindles, motor rotors, and any other elements having repetitive motion.
  • 2. Observation of vibrating members, fuel-nozzle spray patterns, and vibrations of components under test in wind tunnels.
  • 3. High-speed photography of repetitive or non repetitive motion

The circuitry and mechanical design of the GenRad 1538-A Strobotac electronic stroboscope are similar to those used in the Type 1531-A. The flashing rate is controlled by an internal calibrated generator and is adjustable from 110 to 150,000 flashes per minute. This over-all range is divided into four direct reading ranges on the large, illuminated range-control knob. To avoid reading errors, only the range in use is illuminated. A large-diameter flashing-rate control, concentric with the range knob, provides precise setting of the flashing rate.
A variety of trigger inputs can be used for flash synchronization. Contact closures, pulses, or sinewave signals will trigger the flash and an output trigger is provided so the stroboscope, in turn, can trigger another device. A 1536 Photoelectric Pickoff can be used with a 1531-P2 Flash Delay to provide an adjustable delay between the time a selected point on a moving object passes the pickoff and the time the strobe flashes. Single-flash photographs of high-speed motion are a snap with any still camera when the 1531-P2 is used.

GENRAD 1538 STROBOSCOPE BASIC SPECIFICATIONS (Full specifications can be found on the datasheet)

Calibration: Accurately calibrated flash rates to 150,000 per minute,accessories for brighter light, extension lamp, and battery operation.

Flash Rate 110 to 150,000 in 4 ranges: speeds to 1,000,000 rpm can be measured.

Accuracy: 1% of of reading after calibration on 670-to-4170 rpm range against 50-to-60 Hz line frequency.

External Trigger: Input and output connections via phone jacks

Input: Contact closure, pulse 5; +1 V pk-pk, or sinewave 3: 0.35 V rms for f > 100 Hz (3.5 V at 10 Hz).

Output:: +6 V behind 400 Ω

  Duration  Energy watt-seconds  Beam Intensity candela 
at 690 fpm 
3 µs 
at 4170 fpm 
1.2 µs 
at 25,000 fpm 
0.8 µs 
at 150,000 fpm
0.5 µs