Sent off the penultimate prototype boards to manufacturing this morning.
Here are 3D renderings of each.
Feeling very pleased with the layout. Should prove easy to assemble, and have good noise rejection characteristics.
The final version of VCO board will be SMD, and organized for robotic assembly, but I wanted to begin with a through-hole version; both to verify the circuit design and basic layout, and to make available to interested builders who don’t enjoy SMD work.
Also created a Bill Of Materials (for mouser.com) this morning and put in an order so I can validate it before publishing.
Waiting on the good folks up at KrlBantry in Manchester, NH, to deliver a batch of custom spec 3k Tempco resistors. Should have the first batch in early August. At the moment, the prototype experiences frequency drift as the transistors in the Exponential Converter heat up. Going to thermally bond the 3 transistors in the Expo Converter to the Tempco, and pack it in some kind of foam or potting material, to minimize thermal gradients between them. This is the way Dennis Colin did it in the AR-317 and it works extremely well.