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Robots & Dinosaurs is located in 10/27 Bank st, Meadowbank . We’re open Saturdays from about 11am and some weeknights, but you should check by asking on our mailing list.

Beco Blocks, the 3d printable, snap together, ball and socket based building blocks.

Initially created as a prototype for another ball and socket based project, these blocks functioned so well I decided to make a number of variations to allow the creation of more complex objects.

Beco blocks are great as toys and i suspect might also find practical applications for things like:

  • Light duty hinges.
  • Printable helping hands
  • Internal skeletons for soft toys.
  • Snap together bracelets.
  • Mini pose-able art mannequin

Beco blocks thus far have been printed on our Makerbot using ABS plastic. The first Beco block printed was very lonely, being the only Beco block in existence with no friends to snap together with. Some time later when I finally learnt how to use the Makerbot myself I started printing more, and was surprised to discover how effectively they clicked together. There were practically no design iterations in making the original male-female Beco block, i was just very lucky with a ball and socket size ratio which seems ideal. The 3d models for Beco blocks include struts which allow the printing of the ball in a horizontal orientation. The struts can quickly and easily be clipped off using light wire cutters. There is plenty of room for improvement in the design and additional brick variations. I have only designed enough types of bricks to build a basic figure so i hope others add to the collection. The STL files are available at Thingiverse here: http://www.thingiverse.com/thing:1983

Geigerduino (part 1)

Over the last couple of months, Gav and R3becca have been discussing a new project idea - the Geigerduino. The idea being to be able to build an simple device that can detect cosmic rays or other radiation using a Geiger-Müller tube and an Arduino, and then publish the details so others could do the same. In late August, whilst having an R&D group dinner at Rockdale McDonalds, Gav quizzed me about generating high voltages, and I drew a rough schematic of a DC/DC boost converter (on a napkin of course). He told me the goal was to generate a PWM controlled voltage of up to 1000 V, using USB as a power supply. Having planted the seed, over the next two weeks I did some additional research and realised we should try a DC/DC converter using an isolated transformer with a voltage multiplier to get this kind of output. So, two weeks ago, we began prototyping this at the space. I built up a simple circuit on a breadboard, using a small transformer, some high voltage diodes and capacitors, and a MCP14E5 mosfet H-bridge driver chip. I had acquired a small batch of these transformers from a surplus electronics place a few years ago, and they seemed appropriate with a DC resistance of 11.5 ohms on the primary, and 2,300 ohms on the secondary. I had no other specs, but I think they were intended for generating HV to drive EL or CCFL lighting. The MCP14E5 is actually intended to drive the gate of power MOSFETs, but I had it handy, it is fast and can supply significant current, and it seems to do the job. I also needed a signal source to drive the transformer, and seeing as R&D had recently done a group purchase of Bus Pirates (preorder 2), I decided to use one of those. The Bus Pirate has a PWM generator mode that can generate 1 kHz to 4000 kHz signals with varying duty cycles.

gd1

So, what was the result - first we tried 1 low frequency, possibly 10 kHz, and got almost 500 V DC out.

gd2

A bit of tweaking, and we found that these transformers work best at around 50 kHz. This picture was taken when we were using about 8 V at 200 mA to drive the transformer.

gd3

Yes, we are generating nearly 800 V DC using USB and a simple breadboard circuit! Gavin and I then made up these circuits on some prototype PCB’s, and found we could generate 600 V DC quite nicely from USB power. Gavin even incorporated his Arduino DangerShield for PWM control.

gd4

There is a 10 M ohm load resistor on the output of the circuit. This provides some load (50 uA at 500 V), and helps to discharge the capacitors when the PWM is disabled. Be aware that many cheap multi-meters have an input impedence of only about 1 M ohm, and the load will drag the output voltage down below those shown above. Also, many meters and probes are not rated for use above 600 V (including the scope meter used in the photos!) Warning: Experimenting with high voltage is dangerous - both in terms of electric shock, and damage to your equipment. You have been warned. More to come… - Kean Reference material: http://en.wikipedia.org/wiki/High_voltage http://en.wikipedia.org/wiki/Boost_converter http://en.wikipedia.org/wiki/DC_to_DC_converter http://en.wikipedia.org/wiki/Voltage_multiplier http://en.wikipedia.org/wiki/H-bridge http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en531148 http://dangerousprototypes.com/bus-pirate-manual/

Member’s Projects — ‘Light Interrupted’ by Adam Synnott

Introducing a new category here on the blog, Member’s Projects. We’d like to show off some of the things people are making, taking apart, remaking or whatever! Our first project is by Adam Synnott, and is called ‘Light Interrupted’. It was recently featured in ‘Serial Space’ in Chippendale.

Light Interrupted

Light Interrupted Light Interrupted is a rear projected FTIR multi-touch display using a combination of Touch Designer and Max/MSP the screen. Adam is currently in development of a muti-touch 3d painter/modeller, an RSS fed globe, some reactive grass and a 3d fish tank.