This one just got traced over on FSB. Apparently the heaviest of Bjorn's Honey designs. Here's the schematic for reference. Note: In the schematic the source and drain on Q1-2 are reversed from the way they are normally oriented, but I recently learned JFETs are generally symmetrical and will work either way. The original is built on a PCB that several of Bjorn's circuits can be built with and is laid out for TO-18 package JFETs with a different pinout than the TO-92 packaged 2N5952. I'm wondering/guessing it was easier to swap the drain and source legs when fitting the transistor to the PCB, but perhaps other/earlier versions of the circuit used TO-18 JFETs and had the drain and source oriented the "normal" way. That's my reasoning and as a result I've reversed them to the "standard" orientation in this layout. Also I altered the polarity protection method to fit on the board better. I'll shut up now.
Verified.
ReplyDeleteI substituted 2.7k, 5.6k, and 15k resistors in place of the 2.6k, 5.67, and 14.7k, respectively. Q2's voltages were a little off from the schematic (keeping in mind the source/drain swap compared to the original), but my build sounds close to the demo.