Buck and Boost Drivers, Testing, Modding, and Discussion (Pic Heavy)

I’m trying to understand these drivers, I don’t quite understand what the Opamp is doing in this?

The opamp is part of the current regulation and control function. It compares the voltage drop across the R7 sense resistor with the voltage signal that represents the commanded or set-point current.

When the sense voltage is below the command voltage, then the opamp output signal provides feedback to the driver that more current is needed, i.e. to increase the current.

Once the sense voltage equals or slightly exceeds the command voltage, then the opamp output signal provides feedback to the driver to hold or slightly reduce the current.


Μmm, seems I've managed to slightly fLIck-up my modified TA13's H2-C driver after a reassembly in which I clumsily wetted with solder one side of the legs of the integrated circuit closest to the output+ pin, can be seen at half past seven in the following KD's shot:

(picture from Kaidomain was removed)

I've done my best to clean the IC's pins off excess solder, it looks clean and the thing works. However, it now has some weird oddities: sometimes it may not power up, requiring an additional switch cycle, or it may enter an unexpected early low voltage warning which resets after a half-press… Oddity frequency is uncommon, fortunately.

Oh! What chip is that? LoL!

Cheers ^:)

Sat, 03/31/2018 - 04:13

“FWIW an Eagle Eye A6 can also (with a little work) accommodate an H1-A and still use its retaining ring”

This is a very interesting revelation that I’ve never known about, I’ve been studying options for building a tube light similar Jensen567’s mod, and with this it sounds like the A6 would serve for a better host.

A quick look inside my BLF A6 revealed why: With the built in shelf design the retaining ring is wider, threading to the body tube itself vs the inside of the S2+ removable pill. Although the A6 has a slightly smaller tube I.D., being able to use the ring would solve a lot of issues for this mod.

Since the Eagle Eye A6 is no longer available I’m wondering if their X2 would offer the same benefit of fitting the retaining ring, Not sure if they’re the same bodies? I think they are but I couldn’t even find a review of the EE X2 (only X2R)

Another option that I’m thinking now is the Convoy S3, since it has also has the pill-less design. but I’m not sure how the threading in it’s head compares to the A6.

One more idea came to mind as well for the S2+, I could get an 18350 tube (around $2.00) and cut off a short ring from the end of the threaded portion, make a few tool notches in it (for installation/removal) and use that as a retaining ring, it would be way thinner than the A6 brass ring, which is rather thick, so it may work better to clear any components near the edge of the driver.

(I also posted this idea in another thread that’s dedicated to the H1-A in an S2+)

Now that we're here…

Baby, this is because the tailcap switch is screwed.

Cheers ^:)

Hi, I have problem with H2-C, only has one mode, the lowest: [HELP] H2-C modes. Any ideas?

Question for Jensen567: did you tried any lighted tailcap mod with the H1-A?

Just seen the latest full copper body Convoy S2+ limited edition and was wondering if the lighted tailcap option would work without major issues with an H1-A.

Cheers ^:)

Another little question: Jensen567 I see you boosted H1-A driving current up to 3.75A (R025 + R100 = R020), do you believe it could be reasonable to pump it up a little bit higher? Like for example R025 + R050 = <R017 (4.5A, 16.67mΩ) or maybe R025 + R100 + 2(R330) = <R018 (≈4.2A, ≈17.84mΩ).

I wonder if heat could be a problem.

Cheers ^:)

This is the only real info I’ve found on modding the H1-A sense resistor for increased current. What size is the resistor? I’m looking to order some R100s and very unfamiliar with SMD resistor sizing. So exactly what kind of resistor should I be ordering? Will 1206 1% SMD 0.1 Ohm work?

Measured mine: slightly above 3mm in lenght and about half of that in width, I guess that means it is a 1206 imperial.

Cheers ^:)

Did someone noticed the H1-A's layout is somewhat different from what is show in the product pictures?

I was yesterday playing with one of them and somehow messed up with the capacitors by the inductor's lead, lost one of them and the other is damaged I believe (don't ask me how that could happen, but it gave me reason to send a m@r@n where he belongs). Measured such capacitance (2x capacitors) in a brand new driver and got ≈120µF which is a lot. Gotta have to measure another unit I have at hand unpackaged. Biggest 3.5 × 2.8mm size 16V SMD caps I've found on AliExpress are 47µF each.

May someone confirm such capacitance stack size?

Cheers :-)

According to the above picture the capacitor stack I messed up is at the left side of the inductor. As previously said, I measure either ≈120µF or ≈50µF for that stack. I know this sounds weird but…

Bought these 16V 47µF tantalum capacitors to fix it. They're polarized, this means likely it is that the non-polarized capacitors I am replacing probably were 2x 22µF units.

Mmm, this means just one would do.

Cheers ^:)

Tantalum caps have higher ESR, so there is good chance they will release some smoke.

Ah tantalum caps.

The bane of many Macbooks since 3 generations.

You mean increased blow up chance?

Well, if that is so I'll install capacitors on both PCB “slots” and hope for the best (even if this means capacitance is gonna be about twice).

Cheers :-)

KD has changed some things on the H1-A. Mainly resistor values.

I have read along Jensen567 following all your mods, thanks for posting by the way.
What I’m trying to achieve is about 12v out at about 2 amps driving a triple series Seoul Viosys UV emitters.

I reflowed the leds on to a series 20mm board encase you are wonder about that link.
The R1 resistor is now a 01D (factory) 100k (at least I think its R1) so I assumed the driver works around the 12.6v limit now. So I hooked ever thing up on my power supply and bam the driver works with the series triple Seoul but I can only get about 500 ma output. I thought the sense resistor determined the output current. I had not changed it and was going to limit the power supply current to keep from damaging the emitters, just testing.
I haven’t changed anything on the board yet, looking for advice as what I do need to change on this new revised board. I also want to change the LVP to 2.75v but I would like to get close with output working first. Any advice is appreciated.
Datasheet here: http://www.ti.com/lit/ds/symlink/tps61088.pdf

Now that we're here…

Repaired my driver. Ended up buying ceramic capacitors, a size bigger :-) but made them fit. Bought 'em of 22µF capacity and my guess was right.

I noticed the differences moderator007 describe too.

Cheers :-)

I just fired this thing back up again, this time I hooked up a second meter to monitor voltage to the emitter. I got 11.25V to the emitter’s and at .971ma of current across the emitter. The input voltage was at 4.1V and about 3.25 amps in.
I’m thinking maybe the 100k resistor is still to small to get to the 12.6V limit. 120k or 150k might get there.

Jennsen, while deciding on which 1s boost driver I want to use in my Convoy L6 I saw all your posts regarding the KX70 driver from kaidomain. Thanks a lot for all that data! I also want to do your ldo+cap mod.

What current rating does the 2.8V LDO need? I found some with 150mA for example.

I want to have a max of 4A. The ldo mod shouldn’t change that? What I don’t understand is how your ldo mod changes the lower modes?

From what I see and fathom here, LVP condition is when voltage at pin 3 goes down to 1.5V. If so, replacing R11 with an 8KΩ resistor results in 2.7V LVP, or changing R12 by a 12KΩ one does 2.75V LVP.


For the love of God, may someone point out what/where are the 10KΩ “01C” resistors pertaining to the MCU's pin 3 battery input divider? Seems like that 01C below the MCU in the picture could be R12, but where the @#$% is R11? May someone confirm? I can't figure out if something else has changed from here, may have to peek at my drivers.

Cheers ^:)