Since starting d.c.~daylight in 1995 — I have designed many electronic circuit elements and complete products for customers such as my former employer the BBC — London Weekend TV — Sega — Astra — Sick AG — Sunkist — Marconi — Contraves Space AG and General Dynamics to name a few — I have also designed and developed some excellent audio equipment both for myself and others but this is more a labour of love as so many hours can be spent seeking audio nirvana

Despite this being the "digital age" almost all of my work is discrete "analogue" design which — after all — is my speciality — Even problems with high speed "digital" track layout and on PCB transmission lines for high speed digital modulation of diode lasers were solved using traditional analogue and RF techniques plus a lot of common sense and experience

One of the main challenges for analogue designers is wide temperature range — In the past it was tuned circuits or d.c. amplifiers drifting wildly — Nowadays it's extremely sensitive amplifiers or ADCs or components like diode lasers that self heat 10s of degrees in a fraction of a second and thermally self destruct before you can see why — So many designs using basic analogue circuitry appear to fail randomly but often it is found that they fail at extremes of temperature — But they need not if correctly designed

When designing for small companies that do not have staff specifically trained in electronic engineering or familiar with reading schematic diagrams I draw their schematics showing components like ICs as blocks so that the schematic view directly relates to the components and tracks — This makes following a Schematic to PCB layout much easier for non engineers and much quicker for those with some electronics knowledge or they soon gain greater experience through the clear drawings — An example of such a schematic was this simple Sony Camera interface

There is much more to analogue electronic design than meets the eye [ even when using LEDs and Diode Lasers ] and if you have discovered this the hard way and would like help with such design please contact me

Modelling and Analysis

For many years I have used SPICE and PSPICE modelling as part of the design process — Starting with MicroCap on an Apple Mac I now use MicroSim although I always breadboard as well — To ensure that I can quickly perform checks on designs I have a separate PC setup just for circuit modelling and PCB layout

The nature of the work I do often means there are no standard models or footprints so I create custom libraries and subcircuits for such parts or use Analogue Behaviour Modelling blocks and this I have done for many odd devices like thermionic valves — Diode Lasers — custom RF transistors for space flight and semi custom ICs

PCB Layout

PCB layout is a natural extension of the design process and the Gerber files I produce are linked to the schematic ensuring no "crossed wires" and often correct first time PCBs which saves time and money — I also make PCBs from customer supplied schematics and re-engineer existing designs but re-engineering often means just that — not simply copying a layout but improving the design often changing and reducing components or producing a new layout with more readily available or cheaper components or migrating through hole to SMT or vice versa

Most designs I make are less than 100 components or have a schematic no larger than an A4 sheet and in this area I am able to be competitive as well as creative — Special care is taken at the PCB layout stage because with Analogue and RF layouts the PCB is often a critical component — Layouts can be optimised for thermal constraints in very small areas like the Diode Laser driver electronics I designed for the Vector Technology range of Laser Modules where small areas of copper are also thermal shunts