Helm-ets Deep.

So, one day I thought I felt that my helmet had become noisier. Weird, because I have a deflector on my windsheld AND I’m quite short. When I stopped to refuel I realized that the bluetooth plug had fallen off:

I thought that replacements might be avaliable, but having a 3D printer and skills, it was just easier to take some measurements and make a new one.

That turned into a downward spiral of creativity I hadn’t planned at all… :033:

The thing is, I have an internal bluetooth (Just Speak) because I hate the bulkyness of the external ones. The only drawback is that for charging I have to fully open the helmet and remove a foam flap to access the microUSB port, wich is slightly annoying.

As you can guess, while working on the plug I wondered…”Can I add a microUSB port to the plug and connect it to the inside of the helmet?”
Well…it seems I can.

So I proceeded to design a flexible PCB to connect it to the inside.



A few weeks later:

This was my first flexy pcb, so I messed slightly. Especially by not optimizing the connector position (vertical instead of horizontal) so the pcb was more expensive that needed. It also looked a bit weird, with a forced bend and such.

In any case, the thing worked, but then I realized that I would not be able to check the status light/charging, so a wild idea came to my mind…What if I put some fiber optics in there?

So I modified the design to include a 1mm PMMA fiber in there. Interestingly enough, I already had to add a spacer in the inside connector anyways, because the male part was 2mm longer than the socket.

And the spacer:

And also, redesigned the pcb:


Meanwhile I waited for the pieces, I realized that the endcap didn’t had any form of retention, and altough that wasn’t a problem per se, I knew it would be lost at some point. So…

Yeah this had to be done. And with that, when all the pieces arrived:

Fucken awesome!



Damn it looks cool. Also, the insides are prety clean now:


Btw…I opened a Tindie shop, and this is for sale (this is only for CABERG DUKE SMART helmet  + CABERG JustSpeak bluetooth:







Yup, I’m still here, just got lost into sideprojects and jobfinding. Long and amusing posts await.

Semiconductor building will resume soon too. Pieces and kit tools have been gathered and should be arriving at some point by mail.

Vidicon tubes have been gathered to start electron-beam tests:

A curve tracer kit has been bought, because I’m a lazy bastard and I didn’t want to botch one in the workshop. :P

More news soon!



The Project is finished! A sort-of-proof has been made:

(Diode-ish behaviour in a home doped silicon shard)

The documentation is done. Two books have been written. (well, more like one book and a phamphlet):

Semiconductors @ Home – Compendium!

(a knowledge gathering on all the machines and accesories built for the project)


Semiconductors @ Home – Cookbook!

(a step by step guide to use said machines, or similar, to make the semiconductors. A work in progress, updated often.

A video resume for the project has also been made:

I will be attending the Hackaday Superconference in November 2-5, and will be at the Poster sessions (think of a grown-up science fair) on Friday 2nd, in some obscure corner I pressume.

I will sit beside this poster and bore people to death about all the tooling.

And that’s it for now. Once I come back from the Superconference, posts should resume as “normal”.
See ya!

The wafer in the PMMA mask.

So, while waiting for the turbopump to arrive, my mind was left meandering around, and thinking about the PMMA masking, and the difficulty to obtain very low molecular weight masking liquid…

And I thought…If Silicon is sort of transparent to 10600nm laser light…but PMMA is not…can’t I just use laser etching to patern low resolution features on my test wafers?

With that thought, I prepared a test vector file with lines separated 100µm – 200µm – 300µm – etc… for the laser cutter:

Then proceeded to engrave some acrylic I had around, and McGyvered the shitty microscope we had at home:

That is nice!

That looks very consistent to me! Also, linewidth seems pretty constant (no micro power fluctuations in the laser supply)

For scale, a 110µm copper wire was placed in one trench:

The process idea is as follows:

First etch the PMMA with the laser, but not trying to go all the way, just to the top of the silicon wafer. Then, using PMMA solvant, you eat away some thickness from the leftover PMMA, revealing the silicon on the bottom of the trenches.
After that, an anneal step and you can etch the wafer. This should enable 100µm features, with 100µm spacing.

You can’t cheat physics…

…and neither can I.

So, where have I been? Up to no good, apparently.

Up until now, I have skipped altogether the way I was going to pattern the chips. The thing is, you can either have not super expensive paterning tools and expensive resists, or expensive tools and cheap resists.
Obtaining the expensive resists is, well…expensive, plus they are very especialized and sensitive. Also, the optical setup needed is not an easy task either. While looking into it, I found out that acrylic (PMMA) can be used as resist, however, it requires e-beam paterning, wich in turn means you need an electron microscope, wich is not cheap.

Some countries have kind of a market for secondhand electron microscopes, however mine doesn’t. The thing is, if you don’t actually need to scan the thing, but just to shoot electrons at it, could you use any other electron gun?

In theory, you could. It is not a question of voltage (this paper talks about very low voltage PMMA paterning) but to get the assembly to the adequate vacuum conditions. It is not enough to have a good mechanical vacuum pump.

In case you don’t believe me, here’s what a CRT tube does in 40 microns of Argon vacuum:

Here’s the setup:

Having proven that I needed a High vacuum pump, I started working on an oil diffusion pump.

However, the pieces I practiced on where 0,5mm stainless, wich proven trycky, but doable. The final pieces where only 0,25mm thick, wich, unfortunately, altough possible in short runs, it did pierce the sheet on start, wich left the pieces unusable. Shame, they where looking gorgeous:

Now that I had to start again and spend more money on it, a consensus was reached between me and an expert (to be mentioned when, if he, permits it) to try to go for a turbomolecular pump, wich are quicker to reach and stop vacuum, clean in their operation and they look like miniature turbines, wich, to be frank, turns me on. XD


This Boring Company II


Finally got to install the temperature probes. I began by drilling/reaming a vertical hole from the heat face, so even if it was crooked, the start point was correct.

After that, a bigger hole was drilled on the other side to accept a ceramic separator that came with the probe:

To make space for the probe dome and cables, a sharp scrapper was used:

And it looks like this:

The ceramic retainer is attached to the metal plate with screws, with their head on the inside, so they can’t work loose. Also, dual nuts where used:

Now looks like a partial eclipse:

In the meantime, the plasma cutter arrived, and made my life much easier by allowing me to cut simple shapes with zero effort. So, a 3D model of what I wanted was made:

That was transferred to CAD, and then lasercut some MDF stencils to gide the plasma torch:

Other project stencils, but you get the point.

And panels where made.
Plasma cutting by hand (with stencils) is tricky for internal shapes, and thus, all holes had to be tweaked with a file for the modules to fit.

I am slowly getting better at welding (and thick sheet metal helps):

After power sanding:

First test fit alongside the oven:

The control box is upside down. xD

Nuts where welded to hold the cover:

And tabs where added to hold the box away enough from the oven side:

And then the integration began:

Power cabling:

A quick note on fiberglass covered power cable. You MUST crimp the ends before cutting the fiberglass, or it will unravel and create isolation issues. I did mine with some brass tube and parallel pliers:

Since I was not in the mood to make more holes in the box, I opted for the easy cable routing:

And no, the heatsinks can’t get hot enough to damage the fiberglass cable or the silicone cable, altough the second one might get sleeved up to the probes at some point. Let’s say it is workshop friendly as long as there are no kids around. XD

When you want a compact unit, things like this happen:

Testing the power section to ensure everything is ok:

I left it cooling overnight and then installed the timer. It is NOT connected to the power section, it’s just a convenient place to have a programable clock/alarm.

The controller also has a double circuit switch to deactivate the SSR’s, so the oven power is OFF but I can still monitor the temperature.
The oven now just requires some external quartz tube supports, but it can be used as is for now.

See ya!

The hunt for Pump October.

If not for the help of Niklas Fauth the race for the turbopump wouldn’t have happened. (all turbo maintenance and repair performed by him too)

As the building of the diffusion pump came to a screetching halt because my TIG welder can’t weld 0,25mm stainless steel, a brainstorming session was held, to decide if further continue with the diffusion pump, or employ the money and time to try to obtain a turbopump.

This model was found on ebay, bid on it and obtained at an amazing price. The ad mentioned it was removed working, and had a return guarantee of 30 days, so we had nothing to loose.

Upon arrival tough, The serial comunications controller was fried, so the driver had to be hacked, altough all monitoring of the pump was lost.

Furthermore, it did not reach full speed, so a dissasemble was in order:

This pump had obviously had a crash. The blades where dented and:

That amount of gunk should not be in a turbo…

After cleaning tough, the pump worked as well as a dented turbo can do (wich should suffice for my needs).

And this, kids, is how I got a turbopump.