The Pass A-40 Power Amplifier — Nelson Pass / 2000

FLATTERED BY THE opportunity to publish a project circuit, the designer is often beset by seemingly contradictory considerations. On the one hand, it is tempting to design a complex circuit as a demonstration of technical prowess; an amplifier with large numbers of esoteric components performing obscure functions. Such an amplifier might be a smorgasbord of electronic technique, featuring class A operation, cascoding, constant current sources, current mirrors, and extra-loop error correction. It would be fascinating to build and perhaps would also sound good. On the other hand, complexity is not a good end in itself and a much simpler circuit… More...

Soldering Tips — Karen Douglass / 2004

PCBoard Soldering can be a kind of art form, when done properly. The result should be a perfect physical and electrical connection, between the part lead and the solder pad on the board. I recommend that you find some solder with low lead content, and rosin core. This can help reduce the amount of lead being dumped into our landfills. You should also have a good soldering iron. Be sure the tip size is appropriate for the job. I suggest a 1/8” 3mm screwdriver tip. Hold the iron tip on one side of the joint (where the part lead and… More...