Project Files of Toroid Inductor Library for Proteus: 100uH Toroid

TOROID INDUCTOR LIBRARY FOR PROTEUS - V1.0 (a 100 uH powdered-iron toroid with soft saturation, and a pop-up)
Designed by The Engineering Projects
www.TheEngineeringProjects.com

IMPORTANT LINKS
Article (read it first - pictures, step by step, every feature explained):
  https://www.theengineeringprojects.com/2026/11/toroid-inductor-library-for-proteus.html
Report a bug or suggest a feature (our forum):
  https://www.theengineeringprojects.com/forum/category/toroid-inductor-proteus-library
The demo runs on our Arduino UNO V4.0 (included) - working LEDs, RESET and a
built-in serial monitor, no Virtual Terminal to wire - its own article:
  https://www.theengineeringprojects.com/2026/10/arduino-uno-library-for-proteus-v40.html
Its switch is our own IRF4905 P-MOSFET (included):
  https://www.theengineeringprojects.com/2026/11/p-mosfet-library-for-proteus.html
its gate driver our own 2N2222A (included):
  https://www.theengineeringprojects.com/2026/11/small-transistors-library-for-proteus.html
and the diode our own 1N5819 Schottky diode (included):
  https://www.theengineeringprojects.com/2026/11/schottky-diode-library-for-proteus.html
Support us (the libraries are free):
  https://www.theengineeringprojects.com/donate

FILE STRUCTURE
Toroid-Inductor-TEP-v1.0/
|-- Proteus Library Files/
|   |-- ArduinoV4TEP.LIB                              201.9 KB   TEP Arduino boards V4.0 (UNO) -> LIBRARY
|   |-- TEP1N5819.LIB                                   9.7 KB   a part the demo uses -> LIBRARY folder
|   |-- TEPBJT.LIB                                     18.6 KB   a part the demo uses -> LIBRARY folder
|   |-- TEPELECTRO.LIB                                 10.1 KB   a part the demo uses -> LIBRARY folder
|   |-- TEPNMOS.LIB                                    17.9 KB   a part the demo uses -> LIBRARY folder
|   |-- TEPPMOS.LIB                                    17.9 KB   a part the demo uses -> LIBRARY folder
|   |-- TEPPOWERRES.LIB                               157.2 KB   a part the demo uses -> LIBRARY folder
|   |-- TEPRESISTOR.LIB                               306.9 KB   a part the demo uses -> LIBRARY folder
|   |-- TEPTOROID.LIB                                 110.3 KB   the library -> LIBRARY folder
|-- Proteus Model Files/
|   |-- TEP1N5819.DLL                                 286.5 KB   its model -> MODELS folder
|   |-- TEPARDUINO.DLL                                883.5 KB   the Arduino board model -> MODELS folder
|   |-- TEPBJT.DLL                                    292.0 KB   its model -> MODELS folder
|   |-- TEPELECTRO.DLL                                294.5 KB   its model -> MODELS folder
|   |-- TEPNMOS.DLL                                   295.0 KB   its model -> MODELS folder
|   |-- TEPPMOS.DLL                                   295.5 KB   its model -> MODELS folder
|   |-- TEPPOWERRES.DLL                               304.5 KB   its model -> MODELS folder
|   |-- TEPRESISTOR.DLL                               311.0 KB   its model -> MODELS folder
|   |-- TEPTOROID.DLL                                 314.0 KB   the model -> MODELS folder
|-- Proteus Simulation/
|   |-- TEP1N5819.DLL                                 286.5 KB   copy of its model
|   |-- TEPARDUINO.DLL                                883.5 KB   copy of the board model
|   |-- TEPBJT.DLL                                    292.0 KB   copy of its model
|   |-- TEPELECTRO.DLL                                294.5 KB   copy of its model
|   |-- TEPNMOS.DLL                                   295.0 KB   copy of its model
|   |-- TEPPMOS.DLL                                   295.5 KB   copy of its model
|   |-- TEPPOWERRES.DLL                               304.5 KB   copy of its model
|   |-- TEPRESISTOR.DLL                               311.0 KB   copy of its model
|   |-- TEPTOROID.DLL                                 314.0 KB   copy of the model
|   |-- Toroid_Demo.hex                                15.2 KB   the demo firmware
|   |-- Toroid-Buck-ArduinoUnoV4.pdsprj                39.4 KB   the demo project
|-- Arduino Code/
|   |-- Toroid_Demo/Toroid_Demo.ino                     3.1 KB   the demo sketch (source of the .hex)
|-- README.txt                                        ~14.6 KB   this file
Total: 7.30 MB (unzipped). The C++ source code of the models is not included.

WHAT IS IT?
A toroidal power inductor lying flat, drawn at true scale: a dark powdered-iron ring 21.8 mm across,
wound all round with copper, two leads
10.16 mm apart - as the Bourns 2100LL-101-H-RC: 100 uH at no current, 46.2 uH at its 4.3 A rating,
winding resistance 36 mohm.
  * A powdered-iron core saturates softly: the inductance starts to fall early and keeps sliding
    down, with no sudden knee. The model's curve
    runs through both datasheet points: 10 % down at 1.48 A (its ISAT), about 25 % down at 2.5 A, 54
    % down at 4.3 A.
  * One analog model on the inductor family's shared model: the flux and its fall with the current,
    the winding's resistance warming with
    the current (the rated current raises it 40 K), backward Euler on the flux. Type any value
    (100u, 47u, 220u): AUTO scales the resistance
    and the currents from the 100 uH part. The copper darkens on the sheet as it heats.
  * Click it at Run for the pop-up: the ring with the field circling inside its core (amber past the
    10 % point), a scope of its current and
    the voltage across it, the inductance against the current with the window's peak, eight live
    values, graphs, an event log and a check page.
The body is drawn as on the real part and to true scale against our Arduino.
The TEP signature and the pop-up are TEP additions.

ONE DEVICE (search "TOROID" in Pick Devices):
  TOROIDINDUCTORTEP  "Toroid Inductor V1.0" in TEPTOROID.LIB (Inductors > Toroidal Power), prefix L,
  model TEPTOROID.DLL. Pins 1, 2.

THE POP-UP
Click the part at Run. Tabs:
    Inductor   the ring from above with the field circling inside its core (more rings, and amber
    past the 10 % point), a scope of the last
               cycles (its current, the voltage across it), the inductance against the current with
               the window's peak, and eight live values:
               peak, RMS and average current, the switching frequency, L at the peak, the energy at
               the peak, the copper loss, the winding's
               temperature. The toolbar: New part and its values.
    Graphs     the live values over the last 2, 6 or 15 s. Live / Freeze.
    Event log  every change and warning; filters All / Changes / Warnings, Pause, Clear
    Check      what the part is doing and what to look at, each with a verdict (green = fine, amber
    = check, red = wrong)
    Settings   theme, text size, open at Run, window size
    Help       report a bug, suggest a feature, article, updates, donate, forum; Copy diagnostics
    for a bug report

TEST STATUS
V1.0: verified in Proteus 8.5 on 31 Oct 2026 (the demo project as shipped: an A4 sheet, an Arduino UNO V4.0).
What the runs showed (the model's own numbers and the sketch's monitor):
  * The project loads and starts cleanly; Timer1 switches the buck converter at 31.25 kHz and the
    sketch holds the output at 5.00 V
    (4.97 to 5.05 V over the run) with a 40-41 % duty, printing every 250 ms; at 0.80 s Q3 adds the
    second 4.7 ohm load.
  * L1 (100 uH powdered-iron toroid, 36 mohm, 10 % down at 1.48 A, 4.3 A rated) at 1 A (0.6 s): 31.3
    kHz, continuous, 1.12 A RMS,
    1.06 A average; the largest peak of the 50 ms window 2.58 A, where the inductance is 73.5 uH
    (-26 %); 45.0 mW in the winding, 25 C.
  * At 2 A (1.5 s): 2.15 A RMS, 2.11 A average, peaks of 3.00 A at 66.6 uH (-33 %); 167 mW in the
    winding, 25.1 C. The largest peak of
    the whole run was 4.13 A (the regulation's swings), still under the 4.3 A rating.
  * The pop-up: Inductor (the ring with the field inside it, a scope of its current and voltage, the
    inductance against the current),
    Graphs, Event log, Check - all four pages followed the run.

INSTALLATION (about 2 minutes)
1. Close Proteus. Extract the WHOLE ZIP to a normal folder (e.g. Desktop).
2. Copy everything in "Proteus Library Files" (TEPTOROID.LIB, TEPPMOS.LIB, TEPBJT.LIB, TEPNMOS.LIB,
TEP1N5819.LIB, TEPELECTRO.LIB, TEPRESISTOR.LIB, TEPPOWERRES.LIB and our Arduino library V4.0,
ArduinoV4TEP.LIB, with the ARDUINO UNO V4.0 used by the demo) to the LIBRARY folder of Proteus, for
example:
     C:\Program Files (x86)\Labcenter Electronics\Proteus 8 Professional\LIBRARY
   (use the folder that already holds Proteus's own .LIB files).
3. Copy TEPTOROID.DLL, TEPPMOS.DLL, TEPBJT.DLL, TEPNMOS.DLL, TEP1N5819.DLL, TEPELECTRO.DLL,
TEPRESISTOR.DLL, TEPPOWERRES.DLL and TEPARDUINO.DLL from "Proteus Model Files" to the MODELS folder
(...\Proteus 8 Professional\MODELS).
4. Delete TEPTOROID.IDX from the LIBRARY folder if it is there (Proteus makes a new index).
5. Start Proteus. In Pick Devices (P) search "TOROID".

RUN THE DEMO
"Proteus Simulation\Toroid-Buck-ArduinoUnoV4.pdsprj" (an A4 sheet) - keep the .hex file and the DLLs
beside the project.
  ARD1:   Arduino UNO V4.0 running Toroid_Demo.hex, its serial monitor built in (window "TEP Arduino
  UNO - ARD1").
  Buck:     +12V (C2 100u) - Q1 IRF4905 (S +12V, D SW, G PG); R2 470 from +12V to PG; Q2 2N2222A
  pulls PG down (D9 - R1 1k - base);
            D1 1N5819 from GND to SW; L1 toroid 100 uH from SW to OUT; C1 100u; R3 4R7 10 W load (1
            A); R6 / R7 10k / 10k from OUT to A0
  Load 2:   R4 4R7 10 W from OUT to LOAD2; Q3 IRLZ44N from LOAD2 to GND (D10 - R5 100 - gate)
  1. Press Run. Timer1 switches Q1 at 31.25 kHz; every millisecond the sketch nudges the duty to
  hold 5.00 V.
  2. At 0.8 s Q3 adds the second load: 2 A. Click L1: the peaks move down the inductance curve.
Closed the monitor? Click the UNO's USB port.

WIRING (the same in Proteus and on a real board)
  buck: the supply - a P-MOSFET (an NPN pulls its gate down, a resistor pulls it up) - the switch
  node; a Schottky diode from GND to the switch
        node; the inductor from the switch node to the output; a capacitor and the load on the
        output; a divider to an analog pin.
REAL HARDWARE:
 * A powdered-iron toroid has much less than its printed inductance at full current: design for the
   value at the load's peak.
 * Check two currents: the peak against the inductance you need, the RMS against the rated current.
 * Mount a heavy toroid firmly (glue, a clip, or a screw with an insulating washer); a metal screw
   loop through the hole is a shorted turn.
 * Keep the switching loop (switch, diode, input capacitor) short.

THE DEMO SKETCH ON THE SERIAL MONITOR (Toroid_Demo V1.0, 9600 baud)
There are no commands. The sketch regulates the output, adds the second load at 0.8 s and prints
every 250 ms. While the duty is zero
D9 stays off the timer: a fast PWM at OCR1A = 0 still gives a one-clock spike each cycle, which Q2
would turn into a full turn-on of Q1.
EXPECTED MONITOR OUTPUT
  Buck converter, 12 V to 5 V - The Engineering Projects
  t=0.25 s: OUT 5.00 V, duty 40%, load 1 A
  t=0.80 s: the second load is on - 2 A
  t=1.25 s: OUT 5.05 V, duty 41%, load 2 A

PROPERTIES (double-click the part > Edit Properties)
  Inductance (VALUE)               100u, 47u, 220u, 1m (a bare number is in uH)
  Winding resistance (DCR)         ohm, or AUTO (scaled from the 100 uH part)
  Current 10 % down (ISAT)         A, or AUTO (the curve keeps falling past it)
  Rated current (IRMS)             A, or AUTO (the current that raises the winding 40 K)
Every run starts again from the properties.

LINKS.INI (OPTIONAL)
The Help page cards of the pop-up open web pages. To point them somewhere else without a new DLL,
put a text file named links.ini next to TEPTOROID.DLL with lines KEY=URL, for example:
  ARTICLE=https://www.theengineeringprojects.com/...
Keys: WEBSITE, FORUM, BUG_REPORT, FEATURE_REQUEST, ARTICLE, USER_GUIDE,
UPDATE_CHECK, DONATE. Only http:// and https:// links are used; lines starting
with # are comments.

TROUBLESHOOTING
* SATURATING: the peaks are past the 10 % point - for a powdered-iron toroid a gentle slope, but the
  ripple grows.
* OVER RATING: the RMS current is past the rating - the winding heats; a part with a higher rating.
* BURNT OPEN: the winding passed 180 C - New part, and fix the current.
* The output will not rise: check the P-MOSFET's pins, the NPN's base resistor and the diode's
  direction.
* "Timestep too small" at the start: a PWM pin left on the timer at a duty of zero still pulses once
  a cycle - take it off the timer.
* The part is not simulated: TEPTOROID.DLL is missing from MODELS and from the project folder.
* The part is not simulated: TEPTOROID.DLL is missing from MODELS and from the project folder. No
  UNO / no monitor window: TEPARDUINO.DLL is missing, or click the UNO's USB port.

BUG REPORTS AND FEATURE REQUESTS
Please post them in our forum with a screenshot, the Serial Monitor text, the
simulation log and the pop-up's Copy diagnostics text:
  https://www.theengineeringprojects.com/forum/category/toroid-inductor-proteus-library

SUPPORT US
This library is free. If it saves you time, please support our work:
  https://www.theengineeringprojects.com/donate

WEBSITE
  https://www.theengineeringprojects.com/

LICENCES AND THIRD-PARTY NOTES
* The model (TEPTOROID.DLL), the symbols and artwork, the other parts of ours in the demo and the
  Arduino Library V4.0 (ArduinoV4TEP.LIB / TEPARDUINO.DLL, with its built-in TEP Serial Monitor
  Advance) are made by The Engineering Projects. The models use only standard Windows libraries; no
  Visual C++ redistributable is needed.
  The C++ source code is not included.
* Arduino UNO V4.0 (ArduinoV4TEP.LIB / TEPARDUINO.DLL, our Arduino Library V4.0 - its
  microcontroller is Proteus's own AVR model): The Engineering Projects,
  https://www.theengineeringprojects.com/2026/10/arduino-uno-library-for-proteus-v40.html
* The .hex file is built from the demo sketch and the Arduino AVR core 1.8.6, which includes
  LGPL-licensed code; its source code is available at
  https://github.com/arduino/ArduinoCore-avr/tree/1.8.6
* Proteus is a product of Labcenter Electronics and is not included. Arduino is a trademark of Arduino SA.
  This library is not made or endorsed by Arduino or Labcenter.

REBUILDING THE FIRMWARE (OPTIONAL)
The HEX file is supplied; Arduino IDE is not needed to run the demo. To edit the sketch, open
Arduino Code\Toroid_Demo\Toroid_Demo.ino, select Arduino Uno and use Sketch > Export Compiled
Binary. Replace the simulation's .hex with the exported HEX. The sketch needs 5,544 bytes of flash
and 224 bytes of RAM.

MODEL SCOPE AND LIMITS
Modelled: the inductance with its soft saturation through both datasheet points, the winding's
resistance and its rise with temperature,
the winding's heat.
Not modelled: the core's loss at high frequency, the self-resonance, the winding's capacitance,
coupling between inductors. The curve between
the datasheet's two points is the model's own smooth fit.

VERSION
TEP Toroid Inductor library V1.0 (Nov 2026). Device TOROIDINDUCTORTEP (TEPTOROID.LIB /
TEPTOROID.DLL). Demo sketch Toroid_Demo V1.0. Demo board: ARDUINO UNO V4.0 (TEP Arduino Library
V4.0) with its built-in serial monitor.