LED Grow Light Station for Chilis and Tomatos

Days are getting longer, and in the afternoons the temperature rises above 10¬įC… but if I’ve learned a lesson the last two years then that growing chilis and tomatos in our living room (although located on the south side of our house) is still far from enough for these seedlings…

So I’ve taken a few hours and built an LED grow light station for them. ūüėÄ

Two LED panels (bought on Amazon for ~ 23 ‚ā¨ each, hanging above two tubs with seedlings.
These photos show the seedlings two weeks after sowing the tomato and chili seeds.

Jupiter Moon photo taken with a regular DSLR and Zoom lens

Yesterday evening I spontaneously made¬†a photo of Jupiter with my Canon DSLR, a¬†(300 mm) zoom lens, and a tripod. ūüôā¬†I was really surprised that I was¬†able to identify the four¬†Galilean moons Europa, Io, Ganymed, and Callisto.DSLR Photo Jupiter Europa Io Ganymed Callisto

I did not expect much as I made the¬†shot from my balcony with room and street lights on. Here in Munich we have¬†a lot of¬†light pollution. At first I thought the small spots were lens flares. Also chromatic aberration is pretty visible due to the manual focus, but I’m still proud of¬†the photo¬†because I did not expect anything special:¬†I first had to compare it¬†with the¬†software-rendered constellation of the moons around¬†the time the photo was taken (see below) to be sure.

Jupiter Moon Constellation 2016-05-28 2100

30th Anniversary of the Chernobyl Tragedy – or – Building a PIN Diode Geiger Counter

Exactly 30 years ago a great disaster struck the region of Chernobyl: a nuclear accident occurred that released a large quantity of radioactive particles into the atmosphere. And it is only five years ago that, with the Fukushima Daiichi nuclear disaster, a second similar catastrophic event has taken place.

These anniversaries¬†did not directly let me build a PIN Photodiode based Geiger Counter, it is more or less¬†a coincidence.¬†The main drive to build such a device was my curiosity and (please forgive me)¬†a fascinating green glow I’ve seen on various fluorescent Uranium minerals under UV light.¬†But in this context it should not be forgotten that at present there still is a significant increase in background radiation in some regions and some agricultural products due to these events.

There are lots of descriptions¬†of how to build such a device; even cheap commercial products (e.g. the Smart Geiger) use such a¬†design.¬†Especially two sites caught my attention: OpenGeiger.de¬†and Das Gammastrahlen-Mikrofon¬†(German).¬†The design I’ve chosen is based on these sources but I’ve begun to further modify it. In this post I’m showing the design I’ve started with. It mainly relies on two BPW34 (Vishay Datasheet) photodiodes connected in parallel, and two transistors¬†to amplify the voltage fluctuations of beta and/or gamma¬†rays striking the diodes. A 9 Volt battery was added to increase the pulse height.

The common approach to protect the photodiodes from light is to use one layer of tin foil and connect it to ground. This should also protect the circuit¬†against electromagnetic radiation.¬†I’ve started with¬†something different and dipped the¬†diodes three times¬†into liquid rubber (Plasti Dip). My hope was to at least allow some beta particles to reach the semiconductor material.

Photodiode with Liquid Rubber Coating

So far I’ve tested the basic design shown above and had mostly noise on my microphone input. I’d say that sporadic crackling has more to do with the 1 hour hacked together design than beta or gamma rays. The liquid rubber seems to block of light, but the simple design is sensitive to electromagnetic radiation. Waving your hand or even movements in about 1 m distance is visible in the sound profile.¬†An additional tin foil shield connected to ground did not change the noise profile, although the EMR influence¬†was reduced. I’ve tested it with two different sound cards (microphone inputs).

I’m currently redesigning the whole approach¬†and expect better results. So stay tuned…

Home-grown Arabidopsis thaliana

Started to grow my own Arabidopsis thaliana (Columbia-0) plants, just for fun. Or maybe a bit out of curiousity as I’m working with its¬†genome sequence datasets… The following fotos were taken about 2 months after sowing…

I did not apply any special treatment, just used simple flower soil with about 20% perlite content and watered them every now and then. For the macro pictures of the blooms I used an adapter (retroadapter) to reversely attach a lens to my camera.