We can offer assistance and task offloading in audio projects, power electronics and metrology projects, MCU firmware development assistance and consulting. Feel free to contact us by mail at
and provide us a general description of your project and how you think we can help, so we can discuss further.
Our current areas of expertise :
Ltspice modelling for analog and mixed signals, and general drafting of circuits.
NXP iMXRT1060 based MCUs firmwares and rapid prototyping as well as EDA sketching
Assistance in coding for Steinberg VST3 plugins.
USB host and device modes for aforementioned MCU
DAC / ADC interfacing.
Proof-reading and review of LLM generated documentation.
Prompt engineering for general purpose electronic projects.
Standard rates :
From 40 EUR/hour depending on area of expertise, project complexity, and timing constraints.
TL072 Op-Amp model or any other Audio grade suitable op-amp
Explanation :
It assumes a single pickup with a copper wire wound around a Nickel Steel alloy core. Saturation is modeled.
In a realistic model, the magnetic excitation of the coil is as follows :
A) Magnet generates (magnetostatic equation) magnetic field. (2)
B) Vibrating string is magnetized. Creates a time varying magnetic field according to motion equations (1) & (4)
C) Time varying magnetic field is picked up by the coil wrapped around the pickup pole cores.
Because of the limitations of integration in Ltspice (time integral support, but not space integrals), the model of B) has been simplified – As if the magnet was vibrating like a string at a distance of the pickup, but taking into account geometry. A better model would be possible using “C++ black boxes” as it is possible now with QSpice, as the DLL engine is Turing complete which allows to render space integrals easily. The model of B) excited by A) is doable in QSpice and is explained in the paper (4). So B) has been simplified to a simple coupling parameter int the form of a factor “chi_wire” (or wire magnetic susceptibility).
Note that the code for such a model of B) has been explored as such, but not validated. It may be added here in a future release.
Finally the core Mechanical model is simplified and according to (1) :
It assumes a string displacement along the Z axis only, and bridge reaction is not modeled.
Bias magnetic field is modelled and as a notable contribution if the pickup core saturation is modelled.
Note that the coil is assumed to be wrapped around a single pole (as just one string is modeled), number of turns has been decreased to take into account the tighter magnetic coupling.
Pickup flux is the sum of self inductance times current + induced flux from time varying magnetic field. Since the preamp is very high impedance the current is negligible and only the EMF from the magnetic field has sensible contribution.
Finally a preamp has been added. (5)
References :
(1) Solving the Sound of a Guitar String Jason Pelc December 10, 2007 (Submitted as coursework for Physics 210, Stanford University, Fall 2007)
(4) Exact expression for the magnetic field of a finite cylinder with arbitrary uniform magnetization Alessio Caciagli 1, Roel J. Baars 1, Albert P. Philipse, Bonny W.M. Kuipers ⇑
