On 29 March 2010 05:11, Peter wrote: > 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. > > Peter Magnetic amplifiers are in still in widespread use. If you look at most modern PC power supplies, they use a magnetic amplifier for the 3V3 output IIRC. RP -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist