my original Aliaser circuit centered around the typical "switched-gate jFET pass-transistor into a cap" idea, where a sharp pulse drives the gate voltage well above and well below the mean Drain-Source channel voltage ... this typically introduces a "pulse noise" on the channel voltage whenever the sampler takes a snapshot ... the interesting thing about the Nyquist Aliaser is that this switchign noise could be minimized by varying the channel DC voltage - but unfortunately not cancel it out by a long shot ... a recent conceptual discovery has lead me to a circuit which gives near-total clock nulling ... ok, perfect clock fundamental nulling with very slight feedthgrough of clock harmonics ... good enough !
this "clock-less" output translates visually on a scope as a disappearance of sharp glitches usually seen at the boundary between sampled voltages ... the youtube video below features the second prototype leading to the final version and shows this clearly ... the circuit was designed for a buddy who's in the studio this summer doing strange and wonderful things with his Bass ... :)~
Dynamic Booster-Compressor // Thermionic Transfer Replicator
JCM(c)2008
"Super-MOJO II"
Linear Dynamic Booster // Tube Amp Feedback Sustainer
JCM(c)2008
Simple Audio Range Sine-wave Oscillator with Shape Control
JCM(c)2008
As far as a quick and dirty audio rate oscillators go it's my favorite, great for testing audio equipment or as an interesting live instrument (great for exploring the chromatic continuum) ... the circuit uses common parts: Radio Shack 272-1139 (1.5v 25mA) or 272-1140 (6v 25mA) bulb, a 1k trimmer (for setting circuit gain and distortion levels), most any standard op-amp, two 0.22uF Ceramic caps, a dual 50k LIN pot, two 9volt batteries a 5k to 100k output volume pot ... if you're gonna box this thing up you may want to replace the Shape/Gain trimmer by a pot ...
tuning the Shape control gives a more constant output signal amplitude to FREQ pot sweep and a cleaner sine wave-shape, though seemingly at the expense of lock-in times as the oscillator becomes glitchy when sweeping the FREQ pot ... off-setting toward higher gain levels allows for more dirty (clipped) waveforms with more "gripping" quality, and better lock-in - ie., little to no glitching with FREQ sweep ... Note: a little bit of RF can creep into the circuit if not decoupling the supply rails - to me it's more interesting this way (it's a hobby, why not ?) ... but that's easy to fix if you don't want it, simply stick capacitance from each op-amp supply pin to gnd - I recommend using a 10uF to 1000uF electro at 25v and 0.1uF ceramic in parallel for good decoupling ...
This unit provides warm chorusing and good leslie simulation at mid speeds ... the LFO speed pot was intermittent so I epoxied a replacement outside on top and stuck a bigger knob for easy foot control ...
To extend the LFO range into high warble territory I short out the speed-limiting resistor - that's R62 33k connected in series with the 250k SPEED pot ... and to extend the depth of the effect a little I short out R65 470k - the resistor leading to the depth control ... two easy mods providing extended performance ...
A synth-like wah when living in a volume pedal - variable-Q filter booster with adjustable gain with enough output for serious amplifier overloading ... I'm told Tony Iommi used one at some point ...
"360+" Bass Preamp/Fuzz System
Possibly The Punchiest Sounding "Vintage Class-A Bass Preamp" Repro Ever Made
VOX issued this circuit in 1974 - it had some connection with Steve Hackett ... Ultra-thick and compressed, this fuzz can produce a nice Brian May singing tone - similar to a BigMuff except for extra shunting diodes ... works well with standard parts ...
