Tuesday, July 21, 2009

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...
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Thursday, July 9, 2009


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!