Electric engineer in the house?

[Ponce]

I have a question, I have a new LED light that I can adjust the power with........I pointed it to my overhead fan and lowered the light wayyyyyyyyyy down and found out that it works like the timing light that you use in a car............does the LED light has some kind of frequency that adjust itself depending on how bright it is?, I can stop the overhead fan or make go slow of fast according as to how bright the LED is...........anyway..........just wondering.

[skid]

Yeah, 60 Hertz....

[skid]

Is it a battery or mains powered LED?

[Ponce]

Two double AA's.........it has a remote to control it with.........CostCo for $19.99 = 3 of them.

[Gaillo]

I'm an EE, among other things.
Most cheap LED lights regulate their brightness using something called PWM (pulse width modulation) - they turn the LED emitter on and off using a fixed time "on" pulse, and a variable "off" time (the greater the off time, the dimmer the light will appear). This, of course, will change the frequency of "flashes", causing the effect you are describing if the frequency is low enough - and "in sync" with a moving mechanical object.

[Ponce]

Thanks Gaillo........that was the answer that I was looking for, now I have to find a use for it.

[Awoke]

LED's are a PN junction, and they require at least 1.7 volts to convert the negative material into positive material, or vice-versa, before they will illuminate.

The voltage is DC, so there is no frequency adjustment. You could use and oscillator to make it flash on and off, if that is what you want to do with it.

As far as light intensity goes, I could be wrong about this, but I think it would depend on the construction of the LED. I think some will glow brighter with more voltage applied, and some will just burn out.

[Low_five]

Theres a little jewish gnome inside the led whose job is to spread confusion inside the house of ponce

[Ponce]

Awoke? I like Gaillo's.... answer better, is simple to understand.......to much info clutters my mind.

Low-five? took care of him......went into my microwave oven......this is now modern times.

[vacuum]

Gaillo is right...they are likely just changing the duty cycle from 100% (max brightness) to something lower like 10%. With an LED you could also vary the brightness by adjusting the voltage on it (and hence the current) but you'd have to have very fine control over your power source because an LED has an exponential IR curve, unlike a resistive light like an incandescent.

Just because it has a frequency doesn't mean its AC...its just on/off as opposed to positive/negative.

[Ponce]

I was plying around with it and I lower the speed of the fan, it works better at high speed and it tell me a lot about it.....still thinking how to use it, many inventions and ideas comes about by accident.

This LED light has a hand held controller that will make the brightness go up or down as you want it to.