Hello there and welcome to my little corner on the world wide web. This is a site primarily devoted to providing comprehensive design details of a select bunch of my hobby electronics projects. By this I mean stuff that I have designed and built at home in my shed to satisfy my own peculiar interests, as markedly distinct from the kind of electronic contraptions I would be responsible for in my day job, with a somewhat higher lab and design budget and where the specified functionality is almost of secondary importance to practicality and ease of implementation. Topics range from home audio equipment including over-kill audio power amplifiers, to HAM radio gear using transmitting tubes, to electronic test equipment. However I mostly enjoy designing, building and studying discrete-component analogue audio and RF circuits. The motivation for authoring such a site stems in large part from inevitably feeling that the effort that goes into each creation is pointless to some degree if kept entirely to myself, and there is of course the warm and fuzzy feeling that comes when someone else recreates one of my designs and gets it working. Constructive correspondence on any of my technical babblings here is of course welcome. On the topic of DIY home audio equipment I'd like to make a few comments to separate myself from the bulk of alternative offerings on the internet. Music is experienced subjectively, so it's probably as inevitable as night follows day that every single engineering facet pertaining to the design of equipment for the task is open and susceptible to pseudoscientific obscurantism and hokum somewhere by someone in one form or another. Such seems to be not least the case when it comes to the topic of building an adequate audio power amplifier. The function of an audio power amplifier is, in my opinion, to amplify the low-level signal from the source to a level sufficient for driving a speaker without adding any audibly perceptible or objectionable coloration of its own. I believe that the requirements for a subjectively neutral amplifier can be defined objectively, in tangible terms, and engineered as such regardless of the technology used - that being thermionic tubes or solid state, bipolar or MOSFET, class A or class AB, linear or class D. These pages are under perpetual construction. Providing even a relatively brief technical write-up for a project can be extremely time consuming and I have numerous chores and obligations that prevent me from updating these pages every day, or even every other day, so progress won't be lightening fast, but I'll do my best.

Audio Design THEORY On The Virtues Of Miller Compensation And Low Open Loop Bandwidth A New Topology For A Current Feedback Amplifier Stability considerations for Miller Compensated Transimpedance Stages -- (Updated 21 March 2012) Some Considerations for Grounding In Audio Power Amplfiers -- (Updated 18 Sept 2012) Capacitors in Parallel - Real Life Measurements -- (Updated 28 Sept 2012) TEST EQUIPTMENT A Test Set For Audio Noise Measurement - (Updated 24/12/11) An Audio T.H.D. Analyser - (Updated 4 November 2012) A Real Time 1/2 Octave Audio Spectrum Analyser - (Updated 17 Sept 2012) DSOMK1 A low frequency digital storage oscilloscope adaptor. LFAMK1 A 1-2-5 stepped attenuator / 1Mohm Z-in input buffer / amplifier / voltage translator board to interface the analogue input of the DSOMK1 to the outside world. SA200K A sweeping frequency spectrum analyser for steady state audio signal analysis with an input bandwidth of DC to 200kHz. POWER SUPPLIES A Synchronous 200V Buck Regulator - (8 March 2012) 6.3V, 4A switchmode filament supply. SOLID STATE AUDIO POWER AMPLIFIERS 1kWPC current feedback solid state audio power amplifier with ultra low distortion parallel modules. 50WPC Solid State Lateral MOSFET amplifier A development of the patented Technics Class A+ concept of a class A amplifier with output voltage tracking supply rails. Class A rated to 1000W. HYBRID TUBE AUDIO POWER AMPLIFIERS 100WPC Hybrid amplifier with solid state driver and push-pull triode (811A) power output stage. 20WPC Hybrid amplifer with solid state driver and push-pull pentode (6CA7/EL34) power output stage (updated 4-November-2012) 3.5WPC Hybrid single ended 2A3 triode amplifier with solidstate driver, uC automatic biasing and hybrid regulated plate supply. PHONO AMPLIFIERS 0.4nV (20Hz-20kHz) Solid State MC Phono Amplifier with active equalisation. <1nV hybrid MM phono amplifier with passive equalisation.

HAM Radio Restoration of an AWA CTM2K Transmitter and its 2200m conversion Restoration of a Commonwealth Electronics AM20 HF Radio Transmitter A complete audio speech processor and keyed low Level AM modulator for 180 meters An AM transmitter for 40 meters.

Other Electronics Stuff A Discrete Digital Alarm Clock - (Updated 23 June 2012)

Mechanical Stuff 1968 Series 2A LWB Land Rover Restoration

Some recent visitors to my garden that made a right mess of my apple tree. They seem to have a particular preference for a little chunk out of every apple that the caterpillars didn't get.

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