Hello! Any update with regards to the supposed PWM MOSFET switching driver? I'm really interested in knowing what PWM frequency it uses, hope it is very high, and some oscilloscope graph impressions. :-)
I am quite pleased with the way it works. There are a couple solderable track pair jumpers on the back, one of which comes soldered. I guess that has something to do with the driver modes.
Today I used VISO Systems Flicker Tester application, calibrated with an incandescent bulb light source with a 100Hz reference value, to measure the flicker output of a torch I have with such driver. Gave me 10.13µs, which corresponds to 98716.68Hz, ≈98.7KHz … a bad result, pretty sure.
Waiting for confirmation, looks great.
Cheers :-)
Originally posted on Mon, 08/20/2018 - 14:39. Edited for a fix.
Don't wanna sound tiresome but, now that I'm sure my flicker tester measurements weren't right, could you please HKJ plug the FastTech's driver in an oscilloscope and measure its PWM frequency? Thanks.
I don't get it. Uses a very powerful AON7520 MOSFET plus what seems to be a current sense resistor in series with it and the emitter, right? If so, it must be using PWM to adjust output current. Either this, or am I missing something?
The mosfet is the linear regulator, a linear driver needs a current sensor, a pwm driver do not. I have written the review now, I do not know when I will publish it.
It was some work, because I had to locate my test fixtures for led drivers and modify my script to use my current test equipment (Everything has been replaced since I last did driver tests).
As far as I understand, a MOSFET is a sort of high current solid state switch operated by driving its gate with voltage.
So that thing is a current adjustable linear design. This means unless you've found something wrong with it, far superior to the still predominant AMC7135 setups it must be.
It can work as a switch, but also as a linear regulator, you just have to use lower gate voltages.
There is also another issue, not all mosfets works well in linear mode (Nearly none do), this means they cannot handle full power, but only a fraction of their rated power.
I did not see anything wrong with it, except the mosfet gets rather hot at full power.
They are still waiting for time on my test stations.
With my current queue I will soon get to them, but if I get large collection of batteries from some of the usual suppliers, they will probably be discarded (They will get too old). There is no indication that I will get a large collection of batteries at the current time.
Do you believe, HKJ, a proper high power linear driver could be implemented with a powerful high switching speed MOSFET used as a switch, plus a high power LC filter to smooth out the output? Sensing Vdrop at the coil would allow obtaining a reference voltage which, after the corresponding high/low comparison, would serve to dynamically adjust duty cycle to maintain constant current at the output for as long as high enough input voltage. I did not formally studied electronics, as you may guess, but the above sounds senseful to me.
I would be interested in a test of Klarus 18GT-36UR.
This is a high-capacity 18700 with a built-in charger. What is special about it is that Klarus claims 10A discharge. So it should have lower IR than other batteries with built-in chargers…but does it really?
I don’t see any source for it yet.
HKJ, if you’re interested in testing it, I can write an update when I find it available.