Electronics with passion: amplifiers and power supplies, FET's and vacuum tubes..

Month: June 2010

Simple way to solder a tiny SMD case

[Читать на русском]

For prototyping, or when reworking a PCB and in need to (re)solder small SMD packages, everyone suggests first to fix opposite corner pins with a gentle touch of a solder, and then do the rest of this juvelry work. Probably it works Ok with reasonably big SMD packages.This time I needed to fix a fleа size SSOP-20 (0.65mm pitch) on a minimalistic SMD-to-DIP adaptor. Certainly adaptor board did not want to stay still on my desk. But the worst thing was - how to hold that SSOP-20 well positioned while grubbing the soldering iron and then trying to touch pads _on_the_opposite_sides_! Mind you I have steady hands and am used to deal with tiny things right from my childhood.The solution came easy in the form of a sticky tape. I luckily had an aluminium one at hand. I believe that a paper one, used widely by painters - will do the job equally well.
SSOP-20 soldered on an SMD-to-DIP adaptor
I used a little

LM317 as a Constant Current Source in audio cirсuitry

LM317 appears to be the most appreciated CCS building block amongst solder-slingers (term (c) John Broskie). Personally I never felt relaxed having such a complex OpAmp-based circuit in the audio-signal path. Nevertheless many routinely utilize this type of CCS in audio, including "pure" tube designs. Recently I was playing happily around cascoding JFETs and MOSFETs for the CCS in my own design.