Build Process 0 Comments October 22

Had a few people interested in my build process (ok really just one person). But I thought it would be good to document anyways. Typically I do things in batches, it makes things feel as if they go by faster, and it seems somewhat therapeutic. As I haven't yet posted anything related to the EFM VCF 8e filter I've been building I'll use that as an example.

I start off with cutting, stripping, and crimping the wires I'm going to need for the panel mounted hardware. I use 24AWG wire for hook up. I also attach wires to the power connector for powering the front panel controls.

I have a number of panels my dad and I worked on when I was in high school. I had decided that I preferred the Modcan format, and thankfully I still do. I sanded them down about 2 years ago, before my synth DIY hiatus. All of the holes are sized for Pomona banana jacks and are a little too big for the pots.

After getting the wires ready I'll play around with the layout of the jacks and pots.

I build a bracket to hold the PCB to the front panel. The bracket is stair case flashing and is a little thin. I've tried two methods for PCB brackets. The first time I drilled holes for the associated panel mounted parts. I liked the idea of this but I didn't use a drill press and the holes are less evenly spaced than the panel!. The second idea was to cut slits in to the short side of the bracket and fit the slices between the panel mounted parts. This works but doesn't feel as secure. Ultimately I want to use a thicker machined panel bracket. I'll probably go with slits and with the thicker material it'll be much stronger.

I take the readied wires and attach them to the different points on the PCB and mount the PCB to the bracket with 1 1/4" 8-32 machines screws and 1" spacers. This puts the PCB right in the center of the jacks and pots. I wish the flashing was longer on the long side as I feel the board is a bit close to the panel mount parts.

Next I hook up any front panel wiring, such as the +/- 15V rails on the pots.

I wrap the wire bundle behind the PCB while loosely attaching it to the PCB bracket. I trim the wires to the correct lengths and solder them to the panel mounted parts. I also trim and solder the front panel power wires. Using zip ties I secure the wires together and make it look neat.

Lastly I tighten down the PCB to the bracket.

VCO 3d Final Stretch 0 Comments October 19

I finished most of the prototype VCO 3d last night. I guess I didn't mention that this is a prototype. EFM voltage levels are typically +/- 10V and have different input/output impedances than Modcan modules. So this is definitely a work in progress. The final unit will have appropriate levels, a pcb bracket that's not made out of stair flashing, and a Schaeffer AG front panel.

I still need to raise the PCB, right now it's kind of butted up against ends of the banana jacks. As soon as I get the PCB raised I'll be able to start in on the electrical changes.

Oh yeah, did I mention that it works!

VCO 3d 0 Comments October 17

I started working on the EFM VCO 3d about a week ago. Some of the panel is completed. Still working out how I want the PCB to attach to the panel. I've used pin headers for all of the front panel wiring which allows me to play around with different panel ideas without desoldering every time.

I'm planning on using the Modcan layout and voltage levels. I like the banana jacks and the assortment of modules. I have an order in with Bruce and I should see them sometime before January (crossed-fingers).