3/27/2023 0 Comments Macspice voltage divider code![]() If you have a simple LC oscillator (one inductor, series or parallel tank) with the capacitor exposed to the environment via a standard rod "antenna".Ģ. My knowledge of analog mixing and volume control is less fleshed out, so I'm sure I'll pull a boner now and then and would highly appreciate any advice in those directions.Ī rather startling (to me) principle I stumbled across lately is this:ġ. I understand oscillators from the digital side of things so that's where I'll start. ![]() So the use of extra transistors for buffering and such shouldn't be discouraged if they suppress undesired interactions in the circuit and don't add too much to the overall complexity. It's not like the old days when transistors were uber expensive. Generic opamps are borderline from a supply current, I/O swing perspective. CMOS gates are borderline (but some kind of circuit employing them might be fun to include). ![]() For actives, I think JFETs are probably OK, but generic bipolar transistors (2N2222, 2N3904, 2N3906, etc.) are preferred from an availability standpoint. ![]() Inductive passives should be untapped enclosed ferrite chokes or single layer air core. photoelectric means of controlling the volume envelopeĪll generic R and C fixed value passives are fine. OTA op-amps, 2/4 quadrant multiplier/mixer ICs, etc. expensive multi-plate panel mount variable capacitors exotic coils like IF transformers, low self-capacitance scramble wound RF chokes, etc. the parallel tank & EQ inductor configuration, which IMO is difficult to tune and maintain To meet the goals, I intend to go the simplest and most direct route possible. to push the state of the art in analog Theremin design This is NOT to yack the ears off of passerby and drown them in tens of pages of thread, nor an attempt to destroy the inherent beauty and mystery of the Theremin, but to grasp what is going on in the most concrete way possible, to further our understanding of it, and to enable meaningful communication between developers and experimenters. A secondary goal of this thread is to lay down some theoretical groundwork in common engineering terms. has sufficient voltage swing at the antennaeĢ. is sufficiently low voltage and low current to enable battery powering uses components that will be readily obtainable for the foreseeable future is tolerant of active component substitutions and passive value changes The main goal of this thread is to come up with at least one complete (pitch and volume) analog Theremin circuit that: The volume side of things is usually an oscillator feeding a bandpass filter, the rectified output of which is used to control a VCA.ġ. The modification of pitch sensitivity and linearization in an analog Theremin is usually implemented via a parallel tank / series EQ coil construct, a configuration that dates back to the earliest Theremins, and was also a favorite of Bob Moog. All I ask is that criticism be kept constructive and non-personal, and that the hawking of outside projects be kept to a minimum.Ī simple analog Theremin can make a good first project for one looking to get one's feet wet with the musical side of electronics, though Theremins are complex enough to sustain lifelong interest.Īnalog Theremins generally get their "voice" from the heterodyning process (non-linearly mixing two high frequencies together and taking the difference frequency). If you have questions regarding my circuits or theory I'll do my best to answer them if you think you've found something wrong I'm all ears. So I'm starting this thread to post my investigations and circuit ideas, and I encourage others to do so as well. the available kit offerings, or at least that seems to be the consensus around here. There seems to be something of a no-man's land between the various random and vaguely suspect Theremin circuits to be found on the web vs. This is foremost a pedagogical thread, here to help budding builders have a positive first experience.
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