Peter Restall restall.net> writes > For the last few weekends I've been playing about with a VCO based around a > ceramic resonator - before that I was using an LC network, but short-term There are several resources (ham radio related) which expand on how ceramic resonators can be and are used to create VCOs. The usual method to broaden the pull range is to use several units in parallel or series-parallel. None of the schemes I saw used a Pierce oscillator, most of them were based on the Colpitts circuit and transistor(s). It seems that 'simpler is better' applies here. A Huff-Puff stabilizer should work very well once the oscillator is stable by itself. (not an expert :-) -- Peter PS: I recently found this gem: http://www.wenzel.com/pdffiles1/pdfs/crvco.pdf which is a coil saturation and variable capacitance tuned VCO. It is very intersting. Even more interesting is the fact that I found two patents from 2009 and 1998 which claim to patent saturation controlled inductance using an electromagnet. One is US and one is from Australia. Obviouly a patent examiner cannot be expected to know that saturation based inductance control was a breakthrough in circa 1890, and led to over 50 years of magnetic amplifier systems being used all over the world and technology. Numbers and references are available upon request. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist