Perfboard prototyping with surface mount 0603 components
Perfboard prototyping is usually done with standard components, but using surface-mount 0603 components is more convenient. A complete resistor and capacitor assortment contains more than 250 values, for standard components stored in drawer cabinets this will cost a lot of space and money. Using SMT components for prototyping is easier, these are available in little assortment book kits.
Here I give a glimpse into an e-bike computer which is built in this way; unfortunately, the schematics and software are not public.
Because of the small size, I use Molex PicoBlade micro miniature connectors; the pitch is 1.25mm. PicoBlade is one of the smallest connectors of its kind. These connectors are widely used in high density electronics, such as laptops. Despite the compact design, the maximum current is no less than 1A.
For the internal wiring, multistranded micro miniature hook-up wire, with an outside diameter of 0.4mm, is used. This wire was not obtainable; it comes from the LCD wiring of an old laptop:
Ultra small Arduino in a 4 x 4 cm cycle computer
The Arduino microcontroller ATmega328 and a Nokia 5110 LCD are built into a cycle computer of 4 x 4 cm. A perfboard is used because it is a prototype.
Standard Arduino boards could not be used, the smallest one is the Arduino Pro Mini, but even this is too big. The solution was an ATmega328, whose pins I have been bent over; carefully one by one. Single row IC socket headers allow that the ATmega328 can be replaced easily.
SMD resistor and capacitor book assortment kits
All the components are SMD 0603. I have bought a SMD resistor and capacitor book assortment kit in China; one booklet contains a stock of as many as 3700 components and cost about $30, including shipping costs.
For SOIC and 0603 components, square pads with a grid of 1.27mm are available:
My favourite electronics precision hand tools
Without high quality precision hand tools it is impossible to do the job: