I have a question about a MR16 LED bulb.

On the MR16 LED bulb I have it is listed as using 50/60hz, and that it is working with input of 12v DC and 12v AC. So it seems like designed for the AC power grid, but would also work on 12v DC battery.

I wonder if I power up a MR16 LED bulb with a 12v DC Lead/Acid battery, would the bulb itself still give off/emit 50/60hz or would the input power of 12v DC change the hz inside the bulb to other/lower hz?

 

If you feed it with DC you will not get any 50/60Hz effect in the light output.

 

I wonder if I power up a MR16 LED bulb with a 12v DC Lead/Acid battery, would the bulb itself still give off/emit 50/60hz or would the input power of 12v DC change the hz inside the bulb to other/lower hz?

Neither. The current through the bulb will be DC, not AC.

 

Thanks for the replies guys!

So even if the MR16 is listed as a 12v AC bulb, it would not emit 12v AC current if it is feeded by 12v DC?

Reason I wonder is that they are possible to dim, and inside many of the MR16 bulbs I have read that they have like a switch that puts them into AC mode by default. Since they can light up with both a 12v AC or 12v DC source, they just go into AC output by standard. Is this a misunderstanding?

Please help explain a little more detail if you are able to?

 

inside many of the MR16 bulbs I have read that they have like a switch that puts them into AC mode by default.

Where did you read that?

 

Probably confusing the operating frequency of the power supply with the line supply. 12 volts AC or DC is just what the bulb wants as a source. From there it goes through a power supply that PROBABLY oscillates at some much higher frequency like maybe 1KHz. I said "Probably" and "Maybe". Meaning I don't know for sure. The end result is a voltage that is sufficient to drive the LED segments in whatever configuration they are in. The frequency of the power source does not dictate the rate at which the LED's may flash. You'd need a scope to be able to detect the frequency - if any - the LED is flashing at. Just so happens I have a failed LED on my bench right now. It's final output is buffered with a 330 µF 80 V capacitor. So the LED on my bench had a constant output of light. No Hertz whatsoever.

I believe you're going on a wrong premises that somehow, 50 or 60 Hz means anything more than what the power supply board inside the LED bulb is designed to accept. Just about all homes US or Abroad operate either on a 50 Hz circuit or on a 60 Hz circuit. What the appliance does with it after it arrives solely depends on the appliance itself. Some clocks designed specifically for a 60 Hz system use the 60 Hz as a counting source for keeping time. If you plug them into a 50 Hz system with a transformer to adjust for voltage, they will keep poor time. However, your computer is operating on whatever voltage and Hz your system supplies. The power supply inside that is called a Switch Mode Power Supply (or SMPS). It turns on and off very fast. The voltage is governed by the amount of time it spends ON versus the time it spends OFF. If you're familiar with PWM (Pulse Width Modulation) then you can understand how a modulation time of 50% will give you 50% of whatever power is coming in. So if you have 120 coming in, the SMPS gives you 10% on time and 90% off time. The result is 10% of 120 volts, giving you 12 volts. The supply also rectifies the voltage so you get a steady 12 volts DC. Capacitors help smooth out the on and off times so that you get a smooth output. Your LED is similar to that. Only, it's designed so that you can operate it on 12 volts AC or DC. Since it's able to work on DC voltages I'll assume (I said "Assume") it rectifies the incoming voltage from AC to DC. So if you put DC in only the associated rectifiers are conducting the voltage and current.

the MR16 bulbs I have read that they have like a switch that puts them into AC mode

Not entirely true. Again, they use the supply power to drive some sort of conditioner that operates at a very high frequency. On and Off. Not Alternating Current. Goes back to the PWM thing I told you about. I think you've just gotten confused a little by something you may have misread. Or something that was told you by someone who didn't know what they were talking about. And sometimes that can even be me. I try to be accurate, but if I've said anything wrong here - there are several people who will point out my error and give you corrected information. I'd listen to what they say here, these guys are pretty dang smart when it comes to electronics and understanding how they work.