Moog 921B

Well here we go; my layout of a Moog 921B VCO is into the stuffing phase... There are rather a lot of wire links... there are also a LOT of trim pots on the board... what was Bob thinking? I think that a lot of them are really there to adjust the controls on the front panel so they agree with the readings on the knobs...

Eye Candy

Have this new (ancient) display for Forbin... it came from a B53 bomber via Texas...

Through the Zero Plane

Some excitement when I got the En129 (ElectroNotes TZVCO) to work. I had a few problems etching the board (see previous posts) and then I had a few problems getting it to work. I then found a few missing resistors from the schematic when I had copied it into the PCB program. Anyway now all is good except for a couple of resistors mounted on the bottom!

Here is the board:
The layout is reasonably tight but there are a few more links that I would have liked. I probably could have juggled around the opamps between the packages to get rid of a few but I was getting a bit fed up with it all by that stage...

This is the result of some very simplistic testing. Looks a bit like some of the photographs that I have seen for the scope outputs from the Teezer and the ZeroOscillator.

Might ask Bernie Hutchins if I can post the layout for press'n'peel to electro-music or somewhere...

On the List "To Do"

I probably need to stop generating Boards and get them attached to some front panels! This is what is waiting for a panel & some knobs. There are about 50 boards here -- some of them will probably go into the prototyping/experimental pile but most seem to be running OK!

More Noise...

Well arced up the Frequency Counter and the Spectrum Analyser and had a bit of a play. The Linearity of Oscillator is pretty good as you can see that over a 10V range it is very close to a straight line -- especially for a couple of transistors that weren't even matched! The lowest frequency response is pretty close to pink and the other two show the increasing frequency response. You can see the lower level amplitude fall as the energy gets spread over a larger frequency range. The picket fence effect is, I think, due to the output being a square wave -- it is well outside the hearing range of most people anyway...

Random Success

Had some success with this board. I layed out a PCB for one of the modules in Thomas Henry's A Synthesizer for the 21st Century. This is the the Voltage Controlled Noise Source. I may put up the PCB layout but it isn't the most compact. It also didn't come out quite as well as I had hoped as the ground plane pour was too tight on the tracks. Anyway about half an hour with the Oscilliscope and a bit of head scratching tracked down the shorts and it is all working well now even if it isn't the most attractive of boards! I think that maybe turning the CMOS devices through 90 degrees might make a more compact board... I have already changed this layout to make the log converter a bit more accurate with some spare LM394's I have got so I may persist... Will try and post some pictures from the Spectrum Analyser tomorrow for some academic interest...

That's Better!

This PCB went a bit better! Cleaning the board with Acetone certainly helped... Will do a bit of experimentation with this once it is working as it is a bit of a different configuration from the OTA and ladder filters...