Thermal laser head for 3D printer? - and sonic screwdriver!!

It's easy (and cheap) to buy thermal lasers for DIY engravers these days. If you head over to AliExpress or Banggood, you can pick them up for peanuts.

I noticed Marco Reps' post on the matter, not long after I got the Cetus 3D printer and had a spot of bother with my finger when I was on Banggood and before I knew it, I had a 300mW blue / violet laser module on its way to me. Including the discount vouchers and the 10% off for using my iPhone, it worked out quite reasonably.

Here's what turned up about a week later, although the guts are only hanging out because I wasted no time getting inside it:

There's some sort of driver board which I guessed was a constant current regulator:

Strangely, it has a bridge rectifier on the input, so is capable of being driven from an AC source:

You can pretty much see what's there without getting too carried away. In fact, it's a 2 stage design: firstly a voltage regulator, then a constant current regulator. I'd been hoping to find some means of PWMing the output but there is none.

Couldn't help sketching out the schematic. Note that the voltage across the LED is about 6V at the rated current, so even without any external components, it would struggle to run at full power directly from a 5V source, which is how Marco Reps used it. Good enough for proof of concept I suppose.

Finally, another moment of profligate indulgence. The ES121 screwdriver is a rather bizarre invention that could only appeal to gadgetboys and armchair engineers. 

It's by e-design, who make some technically interesting stuff. Have a look.

It's not quite so ridiculous if you get it at a promotion price and combine that with vouchers and mobile app discount but it's still completely unnecessary and extravagant. So here it is:

It was the fault of that same bloody mad German, damn him! Take a look and see if YOU can resist.....

Seems to use an accelerometer and DSP (actually, it says it's an STM32) to sense when and how to spin the motor. There's also a tiny epicyclic reduction gearbox in there, presumably multistage. It says it uses "open source application layer" but nothing about the electronics. You can probably guess for yourself - accelerometer, microcontroller, simple H bridge and motor. There's a small display and a USB interface for flashing the firmware and recharging the battery.

There.