Programmable resistor decade
Building a 1 W, 0.5 % decade resistance The seven decade programmable resistor - my variant. Gerry Sweeney designed and built a really neat little SMD decade resistance board a few years ago. He still offers it for sale, already assembled, check it out! You can find it here: https://gerrysweeney.com/seven-decade-programmable-resistor-a-low-cost-solution/ Screenshot from Gerry Sweeney's site. Gerry Sweeney's design is cheap, simple and uses 1 % and 0.5 W resistors in the 1210 size (metric: 3225). Why build my own? I decided to build a similar board, but to use at least 0.5 % tolerance, better temperature coefficient and higher power resistors. This was more of an exercise to see what kind of SMD resistors are available and if it is possible to design it for higher power output and better tolerance at the same time. The answer is that it is, but it comes at a cost. What kind of resistors? I tried to use 1206 size (metric: 3216) resistors where possible. They are a bit smaller an