6ME8

Bought this NOS valve, a 6ME8, to make a Sheet-Beam Modulator as per Ken Stones site where he hosts some of Eric Barbour schematics and articles. On closer inspection I can see that he inside of this one has become a bit munted... Not really sure how this is going to effect the sound but I suppose that we shall just have to give it a go...

Mirrored VCO...

Further to Previous post -- here are the two PCB's (the one on the right has the copper on the top so the IC's are underneath!) The right hand board is configured as the squarewave output and the one on the left is the sawtooth -- this was the subject of the earlier postings.

The Saga Continues!

Been a bit busy with the mundane part of life (you know family, work, that sort of stuff) so Forbin has been somewhat neglected but I have been trundling along with a few bits and pieces. This is our old favourite the Buchla 258 VCO clone... I have been doing a bit more work and have made a second PCB for the wave shaping section only. I have also taken some aspects of a Cat Girl design and worked it into the Waveshaping control along with some buffering and amplification of the output waveforms to boost them to +-5V so they are in line with the other VCO's in the Choir. This picture is to try and help out ericcoleridge with the FET placement. Good plan to write on the board the GDS of the pins just to make sure! It is a bit odd and confusing, you can see the squarewave board mirrored on the right (got the press and peel printed back to front yet again....) There has been some discussion about the pots used and I have used 100K's BUT my waveshape control input has an extra summer and buffer... I will draw up what I have done and try and get it up here soon. It does allow me better control of the wave shape as I was finding that most of my control was up at one end of the travel (more so with the squarewave than the sawtooth).

Forbin LFO comes to Life...

Well the PCB has been made (back to front -- hence IC's on the copper side) and slowly it is coming to life... This dsPIC will give me 20 MIPS and I suspect that I will need more! Certain aspects of the behavior that I had considered will perhaps be saved for later revisions...

Forbin LFO

Goodness Gracious! A front panel! This is the Front Panel for my new LFO! It has 4 outputs which can be phase modulated (and being digital it can do the Through Zero trick without batting an eyelid!). Currently designed for 100Hz to 0.01Hz with the choice of 6 waveforms. What you can see here is the four outputs and the three waveform selections that can be mixed between. The one on the left is down to -5V and the middle is at 0V and the right is at +5V. We should be able to get interesting waveshapes by feeding the outputs back into the controlling inputs! The 4 outputs have measured well and being 12bit it is next to impossible to see any steps on the CRO. Still have some code to write but we shouldn't be toooooo far away.....

Uncertainty Levels > 75%

This is an older board, but Board #4 of the Source of Uncertainty collection is reaching completion! I have even started on front panel layouts and it is looking a bit like two boards on one panel and two on the other or one Mega panel. I also have started on a better version of the AVR noise source. I have decided on a dsPIC version with Grey and Brown noise. It will also support the original noise pattern of the noise generator from National Semiconductor along with a longer, less chuggy version of a 48bit sequence. The dsPIC is probably overkill for the project and I am slightly tempted to do the Grey noise in the DSP! I have a nice SPICE model of an Analog filter design that I have generated but it depends if I can get three outputs from the DSP in a reasonably simple manner...

dsLFO

It has all been a bit quiet recently. The rest of life has intruded a little bit on Forbin activities but I have been slowly working away on a little project which is a LFO with some fairly unique aspects. Not really sure how well it will actually work but we are pretty close to a press'n'peel PCB. Found a couple of poggs ups and I keep adding functionality so that I can use the PCB for some other things as well (an Envelope Generator maybe?) When it is all finished I will probably upload it to some of the forums (well assuming that it works!). I have tried to keep everything "free" so the PCB is layed out with Eagle and kept within the limited capabilities and the development tools are all the free versions of those as well. The PCB is all single sided but it is going to be a fairly careful etch if it is going to work well. Oh and this site has just passed it's first Birthday!