[Oshpark] Hexagon HQ4D Driver Board - 17mm, 4x 7135, dual-channel, single-sided, OTC

Single-sided dual-channel driver board for 4x 7135 and OTC.
Q1 is connected to Pin5, Q2-4 are connected to Pin6. See here for the single-channel version HQ4S.

This driver replaces the Nanjg101 and NanjgAK47 driver, removing the stars, but allowing dual channel and an OTC that does not obstruct the ATtiny13A. Greatest advantage is the Oshpark option of 0.8mm PCB, giving extra room in tight lights.

The board is slightly oversized (17.6mm) to compensate for the 0.3mm missing copper on the edge of Oshpark boards. The result now is a 17.6mm PCB with a copper GND ring of 17.0mm (and the need to file down the board in most cases).

Oshpark Link





MCU: ATtiny13a-SSU
Q1-Q4: AMC7135
D1: Schottky ~0.25V, SOD-323
C1: 4.7µF, X5R or X7R, 0805
OTC: 1µF, X5R or X7R, 0603
R1: 19.1k, 0603, (see comment)
R2: 4.7k, 0603, (see comment)



The circuit follows the Nanjg drivers, so the resistors for low voltage protection and C1 are behind the diode. A Nanjg can be used for harvesting parts, although R1 and R2 in my board have a 0603 footprint, but the stock Nanjg105 resistors (0805) do fit if soldered carefully.

Other combinations of R1/R2 should work, if you either keep the ratio of ~4.06 (I use 33k and 8.2k) or adapt the LVP values in the firmware.

The AMC7135 #1 (Q1) has a large solder pad under the GND connector for better heat-sinking to further minimize the risk of a flickering Moon mode.

You can use either 350mA or 380mA current regulators (Q1-Q4), but I recommend 350mA at least for Q1, as these seem to be more reliable in low PWM modes.
The 7135s that you can buy or harvest can behave quite differently at low PWM levels. I get consistent results for a chosen combination of frequency/PWM-level when I use regulators as identical as possible. I already stock a certain batch seperately only to use them as Q1 in dual-channel drivers.



Back and Front:



Size comparison of the 0.8mm PCB with a 1.6mm board (earlier version):

Now that is a pretty sharp driver! Would make a great nightstand light with a 4c or 5d XM-L2!

Can we talk about making shapes like that in Eagle? I could not do it on my D01 driver, really wanted to for the locking tabs on 2 sides!

Let’s talk shapes. Please explain a bit more what you mean, which shapes, which tabs?
(found your D01 thread)

Ok, so I made the diameter to large by about 3 mm, if I remember correctly with a heavy copper ground ring. I had to do that because the original driver has 2 littl half circle ears that prevent the driver from moving when the batteries are tightened down. This left me with a fair amount of board to dremel and file off for a good fit. I could not figure out how to get Eagle to do the irregular shape of the half circles on 2 opposing sides.

In this pic you can see what I had to file into place…


On second thought I think it’s appropriate to answer in your build thread.

Just seen this driver, it looks very good!

What firmware are you using for it?

I use JohnnyC’s STAR firmware, slightly adapted for my needs.
But there are quite some newer firmwares out there already, which can make use of dual channel drivers. They are best to be found in Toykeeper’s firmware repository.

To make those lobes on a circle I would draw the main circle and the two smaller circles on a layer other than milling with a fine line then zoom in and use the line(arc, milling) to draw them on the milling layer from intersection to intersection and then delete the circles. Basically using overlapping circles to give the outer shape in the one layer and tracing it in the milling layer. I found that to get the arc to land just right I had to initiate on one intersect and size it to a spot diametrically opposed then back off to the next consecutive intersect. For this board it would take 4 such arcs, two for the big circle and two for the lobes. There are other ways but that’s what I do.