Do you think this is ok?

Hi,

Couple of weeks ago I ordered ‘Constant Current LED Driver Board - 3 Modes,5.5-12v,3.0A,P7,MCE

From here: http://www.lck-led.com/constant-current-driver-board-modes-p-501.html?cPath=37_135

It’s arrived, but it looks different to the webpage.

This is what I’ve got:

And this is what the picture on the website looks like:

Do you think it’s the same driver? The invoice included in the package has the correct description but there was nothing printed on the anti-static bag it was in so I don’t know how to ID it otherwise.

Thanks for your help.

From my understanding of driver boards, the driver you received is not going to be constant current. I say this because of the large MOSFET on top. Current controlled driver boards don’t have that but instead use several 7135 chips, like this;

I’d say its a newer revision of the same board, I think I have the same one and a u2 awaiting me turning up a mag heatsink to upgrade my 3d Maglite.

As for constant current boards, an ld25 does not have a load of 7135’s, they just seem to allow the maximum current, then for lower modes, the led is flashed on and off very quickly - pwm. That type of board is only constant current on high.

Constant current is one thing and current controlled is another thing.

If that driver is buck on 2-3cells will most like to be constant current output, that means constant brightness.

7135 boards will be constant current as long as the input voltage is over the forward voltage, they are linear constant current.

As for that advertisement of Truely 1500mA constant current output, it's 1400mA and that refers to the current input.

7135 drivers have pwm even on high, I measured 4700Hz on Nanjg 105C. But pwm does not mean it's a problem and should be really reconsidered as being an issue, it's low frequencies pwm that bother.

ok. So do you think I’ve received what I ordered, or do you think it’s a different driver? I suppose am I asking, do you think I should contact the seller or am I making a fuss about nothing?

Ta. :slight_smile:

Question: what is the large coil for?

Could it be that an impedance is used to smooth the spikes of pwm after the fet, resulting in a non visible light pulsation?

If I'm saying something stupid please correct me, my electronic knowledge is really poor and homemade

Most Buck or Boost drivers use inductor to work. My knowledge of driver and stuff is very basic (not a EE). The inductor is used to store energy and resist energy, which is then supplied to the LED.

In one (initial, power connected) state, the inductor acts as a resistor and lowers the voltage to the LED. Even though the inductor is acting as a resistor, the energy is stored instead of dissipated as heat. After a certain point, the power from the battery is switched off, and to resist the change of current, the inductor now releases the power it stored to power the LED. This happens many times a second when the driver is turned on and that is how buck converters work.

Wikipedia is pretty good on explaining how buck and boost converters work, since the above paragraph is pretty confusing.

Hi Chicken, saw This and the top side of the board looks very similar…

Woody

That board has been around for several years and I’ve never seen one with that metal cased capacitor even though that’s the photo used. It is a buck driver hence the inductor. 7135 drivers aren’t buck, more like burn as they waste excess voltage as heat whereas buck drivers convert excess voltage to current. QC is a common problem with this driver but it is cheap.

Chicken Drumstick,

I've ordered a few of these drivers over the past year and a half and have had great success with them (Yes, look exactly like the one you recieved). I wouldn't worry about it.

-Match

That totally depends upon the driver design. Almost every one that I’ve seen don’t PWM the chips on high (aka direct drive, turbo). If they do, then it’s not really high. The ones that do are trying to limit the current to something below what the driver can actually deliver.

Thanks Match. Hopefully put it to the test this weekend. :slight_smile:

Here I mean the Nanjg 105C and 101-AK-A1 (4*7135). Do you have these drivers?

If I measure the frequency with the DMM I measure 4700Hz for the 105C, if I use the "Selfbuilt technique" (Sound card oscilloscope with the LED connected on the mic input in front of the flashlight) I get the same frequency.

I have just measured the 101-AK-A1 (4*7135) with the DMM and I see 4400Hz on each mode, however this time I have checked the duty cycle and I cannot measure anything on High compared to Medium and Low.

I've seen another member here posting frequencies for 7315 drivers on High mode.