Dielectric: Electrical and acoustic spectroscopy via a PC sound card

This program generates a chirp signal, sweeping over a given frequency range, and drives a given audio output with the signal, while simultaneously analysing the signal coming from an audio input.  This allows electrical spectroscopy and acoustic spectroscopy from ~10Hz-100 kHz to be performed with a £40 sound card.  Note that AC97-channels (such as on-board sound) have lowpass filters built in, restricting the upper limit to around 25 kHz.  Tested with a Creative Audigy 2 ZS, using kX v5.1 drivers.

Download here.


Budget telescope: A Pentax/Nikon hybrid

Now that Pentax SLR cameras are a dying breed, the lenses for them go for next to nothing on eBay.  £30 later, I have six teleconverters to go with my old Hoya 75-205mm lens, in addition to a Pentax/Nikon adapter.  In short, I have a 20 metre focal length on my Nikon DSLR and while the speed/sharpness are going to be terrible, the cost is small.  While the Hoya lens is pretty good even by today’s standards (here),  this is a set-up that should make any photographer cringe:  7.2–19.7m @ f/256.

I had no problem photographing the moon – but finding the moon was quite difficult, since my tripod wobbled all over the place under the weight of all the glass above it.  Focussing the lens was also quite tricky at that distance, the lack of sharpness in the photos isn’t solely due to the amount of teleconverters that I was using.