Piezo Preamp Build and Testing
Submitted by dave on
Submitted by dave on
Submitted by dave on
Leafcutter John has a great post about making Rochelle Salt, which is piezoelectric, and hence can be used as a contact mic: [http://leafcutterjohn.com/?p=1518 Real Sound Cookery].
My folks [http://blogs.ch.cam.ac.uk/pmr/ Peter] and Judith are both crystallographers, so I thought I'd put them to work in the lab (kitchen) to make some nice crystals.
We followed a pretty similar procedure to Leafcutter John, along with some extra info from the crystal guide [http://www.homepages.ucl.ac.uk/~ucfbanf/general/crystal.htm here]
Submitted by dave on
[http://mattvenn.net Matt] put this picture of the next round of Piezo Preamp boards up on his [http://www.flickr.com/photos/matthewvenn/7142271029/in/photostream/ Flickr Stream]. I've removed the piezo -ve input, and tied it to ground, which might loose 3dB of gain, but makes figuring out ground planes a lot easier. I couldn't hear the difference when I shorted piezo -ve to ground, and it makes the layout much smaller and easier. We're down to about 50% of the original size now.
I love using piezo contact mics - they're small and cheap, and can do a whole bunch of different things.
Unfortunately, they can sound pretty rubbish. In particular, they don't like long cables - all of the bass disappears, and they get quite "muddy".
I came across [http://www.zachpoff.com/ Zach Poff]'s writeup of Alex Rice's piezo preamp [http://www.zachpoff.com/diy-resources/alex-rice-piezo-preamplifier/ here], which is a great solution - phantom powered, low noise, pretty simple and a little bit of gain.
Submitted by dave on
Got the first set of boards from [http://mattvenn.net Matt Venn] for prototyping piezo preamps, and they're great! I've soldered both boards, after using the JFET matching described [http://www.nrgrecording.de/html/fetmachting.html here] (NOTE: link seems to be dead - I'll copy the circuit diagram from my notebook).
Submitted by dave on
In the [http://www.mo-seph.com/blog/datavis1 last post], talking about my work with Andreas and [http://www.ed.ac.uk/schools-departments/geosciences/people?indv=1578&cw_xml=person.html Marc], we saw how a bit of data visualisation helped to understand why some output was looking funny, and how the choice of classifier contributed to some strange behaviour. In that case, we were really lucky to spot it.
Submitted by dave on
Here's a video which summarises some data visualisation I've been doing recently. The rest of this post explains the story behind it.
Submitted by dave on
Just got a bluetooth enabled drawing robot working. It's based on Sandy Noble's [http://code.google.com/p/polargraph/wiki/Introduction Polargraph] and code+circuits from [http://www.mattvenn.net Matt Venn]. It uses a pair of stepper motors to wind a pen carrying gondola across a sheet of paper.
Here are copies of some of the presentations I've done
Submitted by dave on
Here is a video and my slides from [http://www.thishappened.org/events/edinburgh-7 This Happened Edinburgh No. 7]. Great night, great talks from [http://www.thishappened.org/talks/oli-mival Oli Mival], [http://www.thishappened.org/talks/jonnet-middleton Jonnet Middleton] and [http://www.thishappened.org/talks/andy-farnell Andy Farnell].