LED's and rotating objects

[justanotherguy]

I use my light at work alot, and frequently check motors for rotation.
Is it worth worrying about a stroboscopic effect?
My coworker thought the motor looked 'awful slow' but
then it looked the sametwhen he checked the other motor.
Then I got to wondering if the LED might give some sort
of strobe effect...........and what the chances would be where I
Might perceive the rotation incorrectly..........?
T

 

[Ualnosaj]

What light are you using? Perhaps it's the effect of PWM (as my uneducated opinion).

 

[justanotherguy]

Today it was a p- rocket X-ML....usually it's a ZL SC60w....

 

[oKtosiTe]

What light are you using? Perhaps it's the effect of PWM (as my uneducated opinion).

I believe PWM can indeed be hazardous in certain work environments. Many fluorescent lights blink a 100/120hz (double of mains frequency) which may cause one to mistake rotating objects to be motionless or move at reduced/reversed speed. I don't see why PWM wouldn't have the same effect.

 

[awenta]

Try an incan and see if it's any different.

 

[Hondo]

Both of those lights use PWM (pulse width modulation) for lower modes. Not all of the SC60 modes are PWM, if I recall, it is like the L2 and M2 that do, and not the higher options. Since this is essentially a high-frequency strobe, it will give the effect you saw. Just try turning them to max brightness, and the problem should go away, the highest modes never use it. And yes, of course an incandescent light won't do it either.

 

[harro]

Point your flashlight in question at a running fan and cycle through the modes. That will soon show you what modes are current controlled and which are PWM controlled.

 

[Swedpat]

PWM will cause a stroboscopic effekt on fast moving objects. An LED without PWM will not cause that effect.