A 7135 does not use pwm, but most drivers using a 7135 adds pwm. The pwm can be anywhere from 100Hz up to above 10kHz.Using a high pwm frequency with the 7135 do have some problems, because the 7135 is not that fast to turn on, especially not when driving a pack of them from a single microprocessor output pin.
Here is an example from one of my driver tests:
The microprocessor has its output on for nearly 2us, but the led is only on for about 0.1us. The rest of the time is used for the 7135 to turn on.
Really?
So, just to verify, a 7135 just burns off excess voltage?
Like when you run a LED on 3 Volts, from 6 Volts battery, with one 7135, the 7135 uses as much power as the LED??
:^\
I wouldn’t trust a DMM’s view on the average voltage.
For the rest this is all a bit over my head…
I find it hard to believe though that a, say, 100kHz PWM-ed power supply can’t be smoothed to its average with a coil and a capacitor, like a class-D amp loaded with a speaker.
How about this cute thingy to modify into a driver?
Probly not, but it’s tiny enough!
I cant tell you how many times Ive torn apart budget flashlights and thought the exact same thing about the chimps that must have put them together. Its sad that so many people have absolutely no pride in their work or such justifiable disdain for their sweat-shop employers.
As always, thanks for the excellent review. I almost purchased one of these cursed drivers but didnt when lck-led’s customer service refused to answer my email questions.
That is correct, but not all manufacturers stays completely within the regulations. With a loose circuit board you do not even need to, because you can just say that the filter must be added to the finished product.
Dang that was quick. Disregard my pm. Well that sucks. I was hoping to get rid of it. Now my light only runs on high for about 20 minutes. If I got rid of that it would go for over an hour.
There’s probably a voltage divider circuit in that mess somewhere. If you can find the right one, removing a resistor could effectively disable lvp by tricking it.