— Electronic Design —

Since starting d.c.~daylight in 1995 I and some colleagues have designed "a few" electronic circuit elements and successfully completed projects for customers such as my former employer the BBC — London Weekend TV — Sega — Astra — Sick AG — Sunkist — Marconi — Contraves Space AG — General Dynamics — Global Laser — TATE gallery. . . — I have also designed and developed some novel 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" most of my work is still discrete analogue design — Problems with track layouts on PCBs for high speed digital modulation of diode lasers have been solved using traditional analogue and RF transmission line techniques — Power amplifiers for space application could use some IC building blocks so were designed using experience with discrete devices and lumped matching to reduce the size

One of the main challenges for analogue designers is wide temperature operation — In the past it was tuned circuits or sensitive d.c. amplifiers that drifted — Nowadays extremely sensitive sensors and ADCs or components like diode lasers that self heat to 100s of degrees in a fraction of a second and thermally self destruct

When working for small companies that do not have staff 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 staff training and following a Schematic to PCB layout much easier and much quicker for those with some electronics knowledge — An example of such a schematic was this simple Sony Camera interface

— Modelling and Analysis —

For many years I have used PSPICE modelling as part of the design process — Starting 1993 with MicroCap on an Apple Quadra 840AV then MircoCapV on PC and now MicroSim —I always breadboard as well — To ensure that we can quickly perform checks on designs we have a separate PC setup just for circuit modelling and PCB layout so no other PC related problems take over the work day

The nature of our designs and PCB layouts often means there are no standard models or footprints for the components so we create custom libraries and subcircuits for such parts or use Analogue Behaviour Modelling blocks — This has been done for many odd devices like Thermionic valves — Diode Lasers — custom RF transistors for a space application and semi custom application specific ICs or ASICs

— 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 everyone time and money — We also make PCBs from customer supplied schematics and re-engineer existing designs

Re-engineering often means re–engineering — not simply copying a layout but improving the design and 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 undertaken are less than 100 components or have a schematic no larger than an A4 sheet because in this area we are competitive as well as creative — Special care is taken at the PCB layout stage because with Analogue and RF layouts the PCB is often the most critical component

Layouts can be optimised for thermal constraints on very small PCB areas like the Diode Laser driver electronics designed for Global Laser and Vector Technology where small areas of copper or the circuit components are used as thermal shunts as well as being part of the electrical circuit