Tonight I took advantage of the milder temperatures and soldered a few SMT resistors onto a scrap PCB as practice. It went smoothly, with the exception of Q1, which hopped when I applied too much pressure while tacking it down. While it looks a bit goopy, it tests out alright. Still a bit too much solder on some of the Rs. Unfortunately I do not have any magnification other than my camera lens, so it’s hard to inspect my solder work in any great detail. Clicking on the photo above does offer a bit of zoom, however. Particularly pleased with R1. A definite improvement over my first attempts. Looking forward to more practice with finer pitch IC packages.
Power Supply Update
After watching Dave Jones’ 5-part lab power supply series, I’m beginning to grasp some analog circuit basics and am eager to try breadboarding my own constant current/voltage supply circuit. To help me design my own power supply unit, I’ve ordered IC samples, capacitors suitable for decoupling/noise reduction on the supply line and op amp bridges, and resistors with a suitable tolerance for the voltage shunt/current sense amp. I was able to scavenge two sturdy potentiometers from some old electronics to feed the op amps in setting the voltage and current levels. Other components, such as the 12-bit DAC, will allow a micro signal the op amps and adjust the current and voltage at a decent resolution (0 to 4096). Jones’ schematic shows two single-turn potentiometers accomplishing the same task.