[WIP] 17mm DD+single-7135 driver / single sided / Dual-PWM

People might be surprised by an infrared flashlight with good throw doing that.

Okay, that would indeed be a fun project… infrared laser programmed to play music on objects in the distance. :slight_smile:

I’m not aware of whether lasers can turn on and off fast enough, but otherwise it seems like it should work. Maybe I should ask over at the laser forums. A quick wikipedia scan suggests it should be feasible though.

You can’t do it with a laser, because it might hurt people’s eyes. It takes a good deal of power.

Perhaps a wide-beam laser instead of a narrow beam? Like, more focused than a SK-68 but not as much as a typical laser pointer? It’d be really cool to be able to trigger the effect from across a room.

Do different fabrics create different “songs”?

At a party, people could walk into the projected wide beam laser that is creating the disco ball effect and have their shirt/jacket/dress/chest hair/whatever sing their own specific pattern. :slight_smile:

So let’s just say I do want to stack a zener. Can you extrapolate on the above? It’s my first time messing with a zener.

The Zener is really actually pretty easy. There’s a “limiting” or “load” resistor, that’s the 100 ohm or 200 ohm or whatever resistor that’s placed on D1’s normal location. So one end of that resistor is wired directly to the MCU’s Vcc. The Zener is also wired directly to the MCU’s Vcc as well as GND. The cathode (striped end) goes towards Vcc, the other end goes to GND.

The Zener will self destruct without a current limiting resistor. It behaves sort of like a low-resistance short to GND. That’s why we add the resistor between Vin (BAT+) and the Zener, it prevents things from getting out of control and allows the Zener to pull Vcc down to the desired voltage.

I’d either put mine diagonally across D1 and R2 (from Vcc to GND) or horizontally from D1 across to FET pins 1-3 (GND).

Post a picture with the Zener laying in place and I’ll verify whether it’s correct.

EDIT: please try and fix the strike-through in your quote of the OP. For whatever reason it’s not working and I’d rather not have anyone get confused. Stacking on C1 is not acceptable for this driver.

Which FET Pins are 1-3? the outboard pins? or from the inner pad of D1 to the outer pad of R2?

Look at the PCB. Zoom in on OSH Park images if you need to.

I couldn’t get a good picture of the real thing, so this will have to suffice.

Looks fine.

Wight, any chance you could stretch this out to 20mm?

Yes, I will stretch this soon.

noob question: If I have no modes, only on/off, what did I do wrong? I’m assuming I have a short somewhere, but what is the most common place to look?

LED- to ground. Reflector is the most common, but I would also look at the connection point on the back of the FET.

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You can also double check that the black lead contact is clear on the star. I’ve seen that either touch the copper star or the side of the pill and give that result.

Check like Richard said that the lead on the mosfet isn’t touching the pill when it’s installed. The black lead from the driver, grounded out, bypasses the driver and goes direct drive.

Just ordered some of these to play! Thanks for putting this out there.

If the solder on the mcpcb sticks up you can carve it off with a knife or cover it with kapton tape(RMM sells thus stuff too).

Hmm, can i use that led - straight to the ground to get a stronger connection to my advantage if i want to do a DD build? So i connect the led - directly to bare aluminum in the pill/shelf instead of first down through the wire through the bare driver board like usual. Or would i get an even lower resistance circuit if i connect the led - to the copper DTP? If i use an conductive heatpaste like arctic silver.

Even better is if you solder the copper star to the brass pill and remove the dielectric layer under led- on the star. No modes, no low voltage protection, no brakes, really bright.