accomplished

Mushroom Cloning – Part 1

Owen — Tue, 13 Jul 2010 00:33:03 +0000

9 days of growth

I’ve begun some experiments in mushroom growing recently. My first step is trying to clone supermarket bought gourmet mushrooms, such as Oyster and Shiitake.

The main motivation behind this started out as an effort to save money, but as is often the case with these things, I’ll probably end up spending way more than I can hope to save on various bits of equipment and massive cock-ups. Either way, I’ll be documenting my progress here.

Sharing shelf space with my homebrew

The first step I took was to do a fair bit of reading on the matter of growing mushrooms. A good source of info was the book Growing Gourmet and Medicinal Mushrooms by Paul Stamets. The book is mostly aimed at a commercial audience, so it goes a bit heavy on the expensive kit and clean room talk for the average hobby grower, but generally the advice seems top notch.

A couple of shroom growing websites also had a lot of useful advice, they were the forums over at Mycotopia and the Shroomery. Both sites are mostly about growing magic mushrooms, but have great tips on growing gourmet shrooms and mostly from the point of view of someone without much money or space, which is perfect for the likes of me.

Stack of agar dishes and 2 growing on cardboard

Next up I ordered some petri dishes and agar. I’ll go into the specifics of making up a nutrient agar in the next post when I have a chance to take some pics of the process, it’s quite straightforward stuff though. I used a malt extract and yeast agar, which is essentially just malt extract, yeast extract, water and agar (to gel everything) mixed together, pressure cooked for 45mins and then poured into petri dishes.

After the dishes were poured and cooled I chopped some tissue out of the middle of some Oyster/Shiitake shrooms that I’d bought at the supermarket, using a heat sterilised scalpel and then burried it in the middle of the solidified agar jelly.

The dishes were sealed up using cling-film to stop any nasties getting in and the whole stack was sealed in a thick plastic sandwich bag and dropped in the airing cupboard to grow. The whole process needs to be kept very clean, but as with the agar, I’ll address that in another post.

That's a mold spot at the bottom

So far only the dish pictured above has grown any mold, which means my obsessive washing during the agar pouring/tissue extraction stages must have paid off. The next step will be to transfer the mycelium from the plates that do well into sterilised jars of Rye grain, but that’s a topic for another day…

Oyster mushrooms cloned onto cardboard instead of agar - 7 days of growth

Dr Who Tardis Mini Garden

Greg — Mon, 12 Jul 2010 19:10:12 +0000

This Display, based on my previous mini Dino gardens, materialised over the past weekend. We’re all big fans of Dr Who in my household. My daughter knew of Daleks and Tardi (i assume that’s the plural) from a very early age.

Back to the project, as before, the base is an 80mm saucer that cost 25p from a DIY shop, the landscape is polymer clay, work in progress shots available here and here. Finally it was painted in acrylics and finished with model railway scatter material.

To hide the gap between the base of the Tardis and the ground I glued a layer of grass around its base, allowing it to be positioned anywhere on the display

Like this? Check out the other dino gardens and our Dalek garlic bread

Mini Dino Garden 2

Greg — Thu, 08 Jul 2010 20:32:20 +0000

Mk 2 of the dino garden. Clay dish (25p @ B& Q) approx 75mm diameter. Polymer clay, scatter material and acrylic paints.

Dinosaur from the Early Learning Centre as before.

Solar pendulum

Owen — Wed, 02 Jun 2010 17:54:37 +0000

A little solar powered pendulum that I made a few years back. It uses a very simple circuit with just 2 transistors, a couple of resistors, a diode and some capacitors. Power is supplied by a two calculator solar panels wired in parallel for faster charging. The power is dumped into a coil which repels a magnet (disguised by some old brass gears) hanging from some fishing line. As the magnet swings back towards the coil the EMF generated lights a red LED in the top post and the power from the capacitors is dumped into the coil again giving the pendulum a little kick, forcing it higher.

Video, more pics and the schematic after the jump.

Pendulum swinging past the driving coil

The frame is made of brass tubing that I soldered together, then threaded the wires for the solar panel and LED through into the box. The box is an old one that I had. It needs some glue on the seams as the constant rocking motion tends to pull it apart slightly. The other little brass bits are from a box of watch parts that I got cheap off ebay and the magnet hidden under the gears is a flat, round neodymium type. I used fishing line to suspend the magnet and found that the nicest way to keep this in place on the post above was to wrap it tightly in thin cotton thread, which has the bonus of looking quite good too.

The circuit is based on the following Solarbotics schematic that I found.

A view showing the LED and solar panels

Detail view of the pendulum gears

The messy guts of the thing

Close up of the rats nest (messy) circuit inside the box

Dino Zen Garden Playset

Greg — Sun, 30 May 2010 15:39:49 +0000

The base is from a mini Zen garden set, the sort they sell in bookshops.

The base is fimo (soft), prodded with a 3.5mm stereo jack and painted in acrylics. The bushes are standard model railway stuff.

This started out as 3 separate projects (use the base, dinosaurs and alien terrain) but pretty quickly merged into one. the Dino zen garden now sits on my desk.

More pics after the jump

Tumbler Update

Greg — Sat, 20 Mar 2010 13:36:26 +0000

I wanted to try and make driftwood after seeing some driftwood frames in a local shop. I couldn’t find any information on tumbling wood, so i went ahead and chucked a few pine off cuts in with some glass. I was pretty amazed by the results, much better than I expected.

The tumbler has been going for 3 months. I check it weekly to oil the rollers and to swap the contents out (or not as is often the case). I learnt very early on to avoid getting oil on the belt, this causes the motor to spin, but the barrels pretty much just sit there for a week not moving.

The barrels tend to leak slightly, and leave a dusty white powder everywhere, but this doesn’t cause any real problems. One barrel even managed to fall off at some point between my weekly checks.

I have at least 2 projects planned for the glass and wood, but its a case of waiting for enough to be produced.

Magical Love Book

Greg — Sun, 07 Feb 2010 15:22:56 +0000

As it’s Valentines day next week, it seems like a good time to post this project from 2008.

Partly inspired by Meredith Scheff’s travel journal this formed the casing for my ‘and finally’ present for my fiancée for Xmas 08. Inside the book is a hollowed section, inside that a purple felt purse, inside that, a sparkly bracelet (the actual present).

The heart on the front is Fimo, formed with a cookie cutter with salt pushed in to the surface. When the salt dissolves, it leaves a pitted metal effect.

The compartment was cut about 10 days before Xmas day. I had to lock myself in the bedroom for a few hours to do it.

The book is one of two i’d bought from a charity shop, 50p each. I didn’t realise until later but both books are dedicated to people with the same surname as my fiancée, a nice bonus (but strange looks when she opened it).

The pouch was a last minute addition made from left over felt from a Halloween project that never happened, the sewing is pretty rough, but did the job.

The final assembly of the book, inside covers and ribbons was completed the morning we left for Wales, requiring me to borrow her hair drier to speed things up a bit.

Renovating a kiln controller – Part 1

Owen — Sun, 24 Jan 2010 17:21:52 +0000

Very luckily I came into possession of a free electric kiln. It came with an old temperature control unit that I’ve decided to get back into working order so I can fire my own ceramics. The controller is made by the Industrial Pyrometer Company, which now seems to have become Mitsco. It uses a clever cam-follower system to regulate the kiln temperature and heating rate. The cam wheel has a scale laid out on it with the rings corresponding to 100C increases and the radial bands equaling 2 hour periods (a full rotation takes 24 hours). A sprung arm follows the edge of this cam around and through a system of gears, rotates a potentiometer inside the unit. An R-type thermocouple probe is used to monitor the temperature inside the kiln providing feedback to the control unit, which is compared to the cam-follower position using a simple Op Amp circuit (based on an F709PC chip). A relay is then triggered to turn the kiln on or off.

When I opened the controller up I found it in surprisingly good condition. It was very clean and the only obvious problem was an Electrolytic Capacitor that was oozing goo.

Dodgy capacitor oozing goo

It was a fairly quick job top replace the cap with a nice new one. All the other components looked fine so I left those alone.

The next task was to figure out how to connect the thing up. Using a multimeter to trace the existing wires back to their connections made this fairly straightforward on the external side. Internally took a bit longer as I had to track all the wires back to their various components. I’ve drawn up a nice colourful schematic of what I found.

External wiring block

Pyrometer schematic, rendered in coloured pencils

I hooked up the mains power after installing working out what should be comnnected where and held my breath…luckily nothing exploded and everything seemed to be ticking over fine. I hooked up a light bulb as a test load and used a cigarette lighter to heat the thermocouple probe. It seems to function as expected, switching the light on and off in relation to the temperature and position of the follower arm.

The relay inside the controller looks a bit too wimpy too switch a kiln on and off, so I’m going to make an external relay box with a nice beefy relay in to handle the actual switching and hook the wimpy relay up to the coil of that one.

There are a couple of variable resistors on the PCB inside the controller that seem to be used to calibrate the thermocouple voltage against the cam-follower arm position. My next task is to hook up the the thermocouple using the new compensating cable that I bought and then put the probe in an oven at a known temperature (about 100C should do it). Then I can fiddle with the resistors on the control board until the relay switches on and off at the right temperature. That’s coming up in part 2.

Inside the controller

Servo feedback mod

Owen — Sun, 10 Jan 2010 22:57:36 +0000

Servo with new feedback wire

Today I’ve modified two of my servos to allow access to the output of the variable resistor inside them. This very simple modification opens up a world of possibilities that really should come as standard on all servos. All that’s involved is opening your servo, locating the potentiometer that provides feedback on where the output shaft is and then adding an extra wire onto the center tap. After adding this wire you can read the voltage present using an A/D converter and following some simple calibration, know quite precisely what angle the output shaft is at.

The actual modification is discussed in detail over at Trossen Robotics so I won’t go into that too much.

Here’s a video of what I cooked up using the newly modified servos and an arduino board.

You can see that as I twist the horn of one servo, the other rotates to match it and mirrors the movement very closely. To do this the value from the feedback pot is read using the analogRead() function. As the output of the feedback line only reaches around 2 Volts at maximum (and goes down to around 0.2V at the other end of travel) the AREF pin of the arduino must have a voltage just above this applied to get good A/D resolution.

To scale the A/D readings I connected a simple voltage divider between GND, +5V and the AREF pin. A note here is that when I measured the maximum output from the feedback pot without the servo being connected to the arduino I measured 1.2V for one and 1.3V for the other and made my divider to output around 1.37V. However, when I connected the ground from the servos to the ground of the arduino board, the voltage seen at the outputs moved closer to 2V, which messed up my readings and meant that the A/D converter was reporting a value of 1023 (max) at about a quarter of a rotation of the servo. This was down to the fact that I was using a separate power supply for the servos which was obviously mismatched slightly from the arduino board voltage. So make sure you hook everything together before you measure the servo voltage and work out which resistors to use in your divider. Incidentally, I used values of 5.1Kohms and 4.7Kohms, worked out using this calculator.

The code I used on the arduino was largely based around the example on the Trossen Robotics page. It’s available to download below.

Download the Arduino Code

Polymer Clay iPod Shuffle Dock

Greg — Sat, 02 Jan 2010 14:22:24 +0000

I made this after becoming fascinated with the dry brushing technique used by modellers. Made using fimo, cling film (to mold the base of the original dock), a rock and knife for texturing and some old coins for a bit of weight.

My original idea was to have tiny N or HO scale people worshipping it, sort of like the 2001: A Space Odyssey Monolith. That never happened, as i was pretty happy with just the rock effect.