Hi all, my apologies if this is a redundant post. I couldn’t really find what I was looking for by searching so I’ll pick your brains a bit. I’m looking for a 17mm 6V driver with LVP. It also needs to be a single PCB (more than likely… 8-| ). So far, the only one I’ve been able to nail down is Richard’s FET with the zener mod. If that is all that is out there it will do, however, a FET is a little much for a MT-G2 methinks. That’s what I’m planning to use, and was hoping for around 5 amps. If only the LVP worked on the zener mods on the Qlites…
Any ideas? The reason I’m insistent about LVP is because most lights I built I end up selling or giving away, and I can only imagine that some folks that see how impressive the MT-G2 is in say, a Convoy M1 or something will want that light. I’d be fine without the LVP myself, but if it gets into someone else’s hand it must be there. I just don’t want any nasty stories coming back to be about exploding cells because of over discharge or such the like.
And, don’t forget to put your MT-G2 on a Noctigon. IMHO, a zener modded FET w/LVP with a Noctigoned MT-G2 would be a perfect match. Those MT-G2’s on Noctigons are safe up to 10 or more amps. Again, only limited by your choice of battery. To be safe, have the fet built with a 30 to 45 second turbo ramp down to high.
Many buck drivers based on QX9920 should handle 2s powering an MT-G2. Some of them have LVP.
The current-version LD-29 buck driver (available from FT/MTN and probably others) can provide 3A output and should work with those input and output voltages, although I haven’t seen any tests of this version in this configuration. It’s got LVP.
Thanks wight! That’s what I’m hoping to do in the future. At this point I don’t have all the goodies required to flash firmware but it is definitely on the horizon. I thought LVP didn’t work after the zener mod because that bridged a capacitor which made the LVP work. Are you saying LVP is configurable in the firmware?
Also in Richard’s store, the LVP with zener mod isn’t an option with the Qlite, only with the FET driver.
Woops! You are correct, an unmodified Qlite never has LVP after the Zener mod.
Drivers like RMM’s Moonlight Special… hmm, I forgot it doesn’t have a Zener option. So much for that. OK, starting over… drivers like my A17-PZL and A17-L81 should have LVP if setup correctly. Only the A17-PZL actually has pads for the Zener and those are for an SOD-123 Zener so the smaller SOD-323 Zener diodes we use now may be a bit of a stretch across those pads - using an SOD-123 sized Zener is the easy solution to that. “Correctly” at this point means building the driver with proper divider resistors to get <1.1v throughout the input voltage range (using a voltage divider calc like the one from Raltron) and then using ToyKeeper’s battcheck test firmware to determine values to plug into the firmware… and then punching those into a real firmware and compiling that and flashing it.
Modifying a Qlite or Nanjg-105c/d to include LVP after a Zener mod is a much bigger pain than just building the A17-PZL from scratch.
EDIT: I failed to point out that if the Moonlight Special takes voltage measurements before the diode AND has C1 after the diode then it would easy to do a Zener mod on that. Even in that case… with that much effort it’s easier and cheaper to build a driver on a fresh PCB.
A bit more info… R1/R2 comprise a voltage divider that compares the voltage read after R1 with an internal reference voltage. Normally a Zener mod fixes the voltage so that pin 7 no longer sees the changing voltage drop after R1 but some newer board designs have R1 connected to B+ before D1 to address this. Some of Rich’s boards as well as some of the oshpark DIY boards include this change in layout. The Zener mod can be done without reflashing the mcu but as wight says, it requires more soldering and recalculating the value(s) of R1/R2.