Loadsa buttons!


Cycling aimlessly around Bangkok, I came across this street side stall (more of a table actually):

I stopped to see what was on offer and came across this old NEC DCR-60-1/780060…

… and all of the buttons reminded me of my friend Pavel’s Pocket Operator (by Teenage Engineering) musical gizmo, and thought that once gutted and innards reassembled, it could be used to make a sequencing musical beat doodad…

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Synth Power Supplies


Sort of following on from VCO madness, I was really looking for the Super Simple VCO (which seems to be actually a 555 timer as a VCO, see the GetLoFi LFO in Ha Ha Ha… 555 fun). However, I got distracted and ended up analysing PSUs and buses for synths.

For ease, in order to power my synth, I had been planning on using a couple of single rail 12V SMPS designed for LED lights, in order to make a dual rail supply, but I started to wonder about the noise implications – as all designs for synths appear to use the old fashioned transformer, rectifier, and linear regulator approach.

(As an aside, Julien Ilett also points this potential noise (as related to buck convertors and SMPS) issue out in Julian builds: a Split Voltage Power Supply (+/-12v and 5v) @5:20. See also, Julian’s Postbag: #85 – E.Ink, Spring Onion, Split PSU (@7:33-8:00), where he mentions that high frequency noise is not removed by the linear regulators in the Split Rail Power Supply Kit Build – SEPIC Cuk Topology).

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Veroboard dimensions


Following on from Veroboard and the Sequencer bus described in Sequencer notes, the sequencer bus consists of two separate stripboard designs:

  • The first step, and;
  • The second step (and subsequent)steps), which all use the same board layout.

With respect to the 9T24H (9T25H) board used for the “Second (and subsequent) Step Sequencer Bus v0.9″… as there are 9 of these boards for the 2-10 potentiometer stages for each sequencer (10 step) stage, is it not more economical to combine on one larger board, of n x 9 Tracks?

Likewise, the v0.7 of the First Step Sequence Bus, requires 12T30H, will that not fit multiple times on a larger size board?

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VCO madness


Simple VCOs using the CEM3340… Three from Look Mum No Computer, two from Electronics Today International, a couple from the datasheet and some examples of commercial implementation.

Also included are a few VCOs implemented using a 555, as well as an approximation of the CEM3340 (also using a 555).

Finally a VCO for Terence Thomas, using a LM566.

(There is a companion CEM3310 – voltage controlled envelope generator, see ADSR madness)

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PCB prototyping


PCB etching, or rather routing, via CNC, as opposed to using Ferric Chloride, is not too different from 3D printing, with respect to the equipment (hardware/software)…

In addition to routing, if you prefer the old fashioned etching, CNC can be used to mark out the traces using a pen, instead of having to print the PCB masks using photosensitive boards…

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