Project Files of 12V Holding Electromagnet Library for Proteus V1.0 (Arduino)

12V HOLDING ELECTROMAGNET LIBRARY FOR PROTEUS - V1.0 (a 12 V DC holding
electromagnet, 25 mm, P25/20 type: the coil, the pull, the plate and its load,
the core's residual magnetism)
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/2026/11/12v-holding-electromagnet-library-for-proteus-v1-0.html
Report a bug or suggest a feature (our forum):
  https://www.theengineeringprojects.com/forum/category/motor-driver-proteus-library
The demo runs on our Arduino UNO V4.0 (included) - working LEDs, RESET and a
built-in serial monitor - its own article:
  https://www.theengineeringprojects.com/2026/10/arduino-uno-library-for-proteus-v40.html
The demo drives the magnet with our L9110S Motor Driver - a SEPARATE library,
not in this package: download and install it first - its own article:
  https://www.theengineeringprojects.com/2026/10/l9110s-motor-driver-library-for-proteus-v1-0.html
Support us (the libraries are free):
  https://www.theengineeringprojects.com/donate

FILE STRUCTURE
12V-Holding-Electromagnet-TEP-v1.0/
|-- Proteus Library Files/
|   |-- ArduinoV4TEP.LIB                              201.9 KB   TEP Arduino boards V4.0 (UNO) -> LIBRARY
|   |-- TEPMAGNET.LIB                                  16.0 KB   the library -> LIBRARY folder
|-- Proteus Model Files/
|   |-- TEPARDUINO.DLL                                883.5 KB   the Arduino board model -> MODELS folder
|   |-- TEPMAGNET.DLL                                 296.0 KB   the model -> MODELS folder
|-- Proteus Simulation/
|   |-- 12V-Holding-Electromagnet-L9110S-ArduinoUnoV4.pdsprj   24.9 KB   the demo project
|   |-- Magnet_Demo.hex                                18.5 KB   the demo firmware
|   |-- TEPARDUINO.DLL                                883.5 KB   copy of the board model
|   |-- TEPMAGNET.DLL                                 296.0 KB   copy of the model
|-- Arduino Code/
|   |-- Magnet_Demo/Magnet_Demo.ino                     4.1 KB   the demo sketch (source of the .hex)
|-- README.txt                                        ~18.2 KB   this file
Total: 2.58 MB (unzipped). The C++ source code of the models is not included.

WHAT IS IT?
A simulation model of the 12 V holding electromagnet - the small round "lifting
magnet" (25 mm across, 20 mm tall, an M4 stud on top) of door holders, pick
and place grippers, robot arms, escape-room locks and sorting machines. A coil
sits inside a steel pot; switched on, the pot's face holds a steel plate.
Our own model:
  * The coil is in the circuit between + and -: 41 ohm (0.29 A, 3.5 W at 12
    V). Its inductance is 1.58 H with the plate on the face and only 0.21 H
    without it - the plate closes the magnetic circuit. Either polarity holds.
  * The pull: about 50 N (5 kg) at the rated 0.29 A on clean, thick steel.
    It goes with the current squared, and it falls fast with any gap: through
    0.5 mm of paint it is half; a few millimetres away it is almost nothing -
    a holding magnet holds what touches it, it does not lift from a distance.
    Over the rated current the iron saturates.
  * The plate and its load (property LOAD, kg; chips on the pop-up) hang on
    the face. When the pull is less than their weight they fall 30 mm onto the
    table. Put back (on the pop-up) places them on the face again; a hand holds
    them there for 0.5 s.
  * Switched off, the coil's current dies away through the driver, so the
    plate lets go some milliseconds later.
  * The steel core keeps a little residual magnetism: about 2 N after a full
    current - enough to hold a light plate with the coil off. A short reverse
    pulse (about a third of the voltage, the L9110S reverses) clears it; a
    pulse too strong magnetizes the core the other way.
  * The watch: HOLDING (the load, the pull, the margin), DROPPED (an overload,
    a gap or a hold PWM too weak), RELEASED (how long after the coil went off),
    STUCK (the residual holds it), RESIDUAL CLEARED, REMAGNETIZED, FELL, HOT,
    OVER-VOLTAGE and the drive (steady or PWM: its frequency and duty).
The symbol shows the magnet from the side: the zinc-plated pot hanging from an
aluminium arm by its stud and nut, the red and black wires from its top, the
arm's post standing on a wooden table. Under the face hang the steel plate and
its load; at Run they fall onto the table when the magnet lets go, and blue
field lines show while it pulls. The plate, the ON LED (green while current
flows), the steel plate and the load, the field lines, the rating line and the
strip under the plate (PULL, CURRENT, STATE, OPEN PANEL) are TEP additions; the
real magnet has none of them.

ONE DEVICE (search "electromagnet" in Pick Devices):
  ELECTROMAGNETTEP "12V Holding Electromagnet V1.0"   (category
                   Electromechanical > Motors), model TEPMAGNET.DLL
  The pop-up panel "TEP 12V Holding Electromagnet" opens at Run (and with OPEN
  PANEL on the strip) - the look of the TEP Serial Monitor. Tabs Magnet,
  Graphs, Event log and Check; gear and ? icons for Settings and Help; the
  palette icon switches the theme:
    Magnet     the load chips (0.1 kg, 2 kg, 4 kg, 8 kg), Put back, Paint 0.5
               mm; the state in big letters (HOLDING, PLACING, RELEASING,
               STUCK, FALLING, DROPPED, ON THE TABLE); the cut-away (the pot
               and its coil, the field, the paint, the plate, the load, the
               table); the live values (the pull, the state, the coil current,
               the drive, the load, the margin, the residual pull, the coil's
               temperature); the last 2 s: the coil current, the pull and the
               load's weight.
    Graphs     the pull against the load's weight, the coil current and the
               coil's temperature over the last 10, 30 or 60 s. Live / Freeze.
    Event log  HOLDING, DROPPED, RELEASED, STUCK, the reverse pulses, the
               drive, the load, the gap, the warnings; filters All / Magnet /
               Warnings, Pause, Clear
    Check      Good for: a magnet that drops its load, will not let go, or
               gets hot - the drive, the pull, the load, the gap, the release,
               the residual, the coil, with tips
    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 30 Oct 2026 (the demo project as shipped: an
A3 sheet, an Arduino UNO V4.0 with its built-in monitor, our L9110S driver -
its pop-up version, from its own library - on +12V, the magnet with a 2 kg
load and RV1 at 70 %; all pop-ups open). What the run showed:
  * The project loads and starts cleanly, "On - drive 100 % = 12.0 V
    average": "steady drive: 11.44 V, 0.279 A (3.19 W) - on the face",
    "HOLDING 2.0 kg (19.6 N) - it pulls 47.1 N on the face: a 2.4x margin";
    the ON LEDs lit (UNO, L9110S, magnet), the plate and the 2 kg load under
    the face; the L9110S's pop-up "FORWARD 100 %", 11.44 V, 0.279 A.
  * "off": "RELEASED - the plate let go 22 ms after the coil went off (its
    current had to die away)"; the plate and its load on the table.
  * The 0.1 kg chip and Put back, the coil off: "STUCK - the coil is off, but
    the core's residual magnetism (2.0 N) holds the 0.1 kg plate".
  * "release": "RELEASED - the plate let go 3 ms after the reverse pulse
    began: it cleared the residual", "RESIDUAL CLEARED - a 148 ms reverse
    pulse (0.130 A at its peak): 0.14 N of residual pull left".
  * "on", Put back, "pulse 100": "REMAGNETIZED - the reverse pulse (0.269 A
    at its peak) was too strong: the core now holds 2.0 N the other way", then
    STUCK again; "on" and "release": "RELEASED - the plate let go 53 ms after
    the holding current ended (a reverse pulse cleared the residual)".
  * The 4 kg chip and Put back: "HOLDING 4.0 kg (39.2 N) - it pulls 46.8 N on
    the face: a 1.2x margin - little to spare"; Paint 0.5 mm: "DROPPED -
    through the 0.5 mm gap it pulls 23.3 N, less than 4.0 kg (39.2 N); clean
    steel: 46.7 N"; Check: "0.5 mm of paint on the plate: the pull falls to
    50 % of clean steel".
  * The 8 kg chip and Put back: "DROPPED - 8.0 kg (78.5 N) is more than its
    46.5 N pull (0.277 A, 11.45 V)".
  * 2 kg, "hold 40": "DROPPED - the 39 % PWM hold (0.111 A) pulls 12.8 N,
    less than 2.0 kg (19.6 N)"; "hold 75" and Put back: "PWM 976 Hz, 74 % duty
    = 8.58 V average, 0.207 A (1.78 W) - on the face", "HOLDING 2.0 kg (19.6
    N) - it pulls 29.8 N on the face: a 1.5x margin"; "on" at the end: 46.2 N,
    a 2.4x margin, the coil at 29 C.
  Plus automatic checks on a PC, 0 failed: 19 on the magnet (50.9 N at the
  rated current on clean steel, 25.4 N through 0.5 mm, 2.00 N residual; 2 kg
  held at 47.1 N, a 2.4x margin, released 22.0 ms after the coil went off; a
  0.1 kg plate stuck on the residual, cleared by a 35 % reverse pulse, turned
  over by a 100 % one; 4 kg held with a 1.20 margin, dropped through 0.5 mm of
  paint; 8 kg dropped; a 40 % hold drops 2 kg, a 75 % hold keeps it; a plate
  put back with the coil off falls; 20 minutes on 12 V: 78 C; a 24 V magnet
  on 24 V pulls the same) and 3 on the pop-up (every page painted).

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" (TEPMAGNET.LIB and our Arduino
   library V4.0, ArduinoV4TEP.LIB) to the LIBRARY folder of Proteus, for
   example:
     C:\Program Files (x86)\Labcenter Electronics\Proteus 8 Professional\LIBRARY
   (on some PCs: C:\ProgramData\Labcenter Electronics\Proteus 8 Professional\
   LIBRARY - use the folder that already holds Proteus's own .LIB files).
3. Copy TEPMAGNET.DLL and TEPARDUINO.DLL from "Proteus Model Files" to the
   MODELS folder (...\Proteus 8 Professional\MODELS). The demo's L9110S driver
   is NOT in this package: install our L9110S Motor Driver library the same way
   (its own ZIP - see IMPORTANT LINKS): TEPL9110S.LIB and TEPL9110S.DLL.
4. Delete TEPMAGNET.IDX from the LIBRARY folder if it is there.
5. Start Proteus. In Pick Devices (P) search "electromagnet".

RUN THE DEMO
"Proteus Simulation\12V-Holding-Electromagnet-L9110S-ArduinoUnoV4.pdsprj" -
keep the .hex file and the DLLs beside the project (with the L9110S library
installed).
  ARD1: Arduino UNO V4.0 running Magnet_Demo.hex, its serial monitor built in
        (window "TEP Arduino UNO - ARD1").
  DRV1: our L9110S driver (pop-up version, a separate library) on +12V: A-IA
        on D5 (PWM), A-IB on D6 (the reverse pulse); its A-OA / A-OB straight
        to the magnet.
  EM1:  the magnet (LOAD=2): + on A-OA, - on A-OB.
  RV1:  10k pot on A0 (the hold PWM after "knob", 0 - 100 %; 70 % in the
        demo).
  1. Press Run. The monitor and the two pop-ups open (move them aside). The
     magnet is switched on at power-up and holds the 2 kg load.
  2. Type in the monitor and press Send: off, on, release, pulse 100, hold 40,
     knob, status.
  3. On the magnet's pop-up: 0.1 kg, 2 kg, 4 kg, 8 kg, Put back, Paint 0.5 mm.
  4. Double-click EM1: VOLTAGE (12 / 24), LOAD (kg, 0.05 - 20).

WIRING (the same idea in a project)
  The magnet's two wires on one channel of a motor driver (L9110S, L298N,
  DRV8833) - then the sketch can also send the short reverse pulse that
  releases a light plate at once. A relay or a single MOSFET works too (no
  reverse pulse then): fit a 1N4007 across the coil (cathode on +) to catch
  its kick when it switches off. The driver's supply on 12 V (the magnet's
  rating).
In the sketch (no library needed):
  analogWrite(IA, 255);                    // on: it holds
  analogWrite(IA, 0);                      // off: it lets go
  analogWrite(IB, 89); delay(150);         // a 35 % reverse pulse ...
  analogWrite(IB, 0);                      // ... clears the core
REAL HARDWARE:
 * A P25/20 draws about 0.3 A at 12 V - a driver or a relay, never an Arduino
   pin.
 * Its holding force is for thick, clean, flat steel touching the whole face.
   Thin sheet, paint, rust, a curved or rough surface all take a lot of it
   away - plan for at least twice the weight.
 * It holds; it does not lift things from a distance.
 * It runs warm when held on for a long time: the hotter the coil, the less it
   pulls.

THE DEMO SKETCH ON THE SERIAL MONITOR (Magnet_Demo V1.0, 9600 baud)
  on         100 % - it holds              off        both inputs LOW
  release    off, then 35 % reversed       pulse 100  a reverse pulse at 100 %
             for 150 ms                               (too strong)
  hold 70    a hold PWM in %               knob       RV1 sets the hold PWM
  status     the drive now                 help       the list
EXPECTED MONITOR OUTPUT
  12V Holding Electromagnet demo - The Engineering Projects
  L9110S on 12 V: A-IA on D5 (PWM), A-IB on D6 (the reverse pulse). RV1 on A0: the hold PWM.
  On - drive 100 % = 12.0 V average
  Commands: on | off | release | pulse 100 | hold 70 | knob | status | help

PROPERTIES (double-click the part > Edit Properties)
  VOLTAGE    the coil's voltage: 12 or 24; default 12
  LOAD       the plate and its load, kg (0.05 - 20); default 2
Every run starts again from the properties, with the plate on the face.

TROUBLESHOOTING
* Nothing happens and nothing is logged: no voltage across + and -, or the
  driver has no +12V.
* DROPPED: the load weighs more than the pull - a lighter load, full voltage,
  no gap (paint), or a bigger magnet.
* STUCK: the residual magnetism holds a light plate with the coil off - send a
  short reverse pulse ("release").
* REMAGNETIZED: the reverse pulse was too strong - switch it on, then use
  "release" (about a third of the voltage).
* The plate stays on the table: a holding magnet does not pull from 30 mm -
  click Put back on the pop-up.
* The part is not simulated: TEPMAGNET.DLL is missing from MODELS and from the
  project folder. No driver: install our L9110S library (TEPL9110S.LIB /
  .DLL). No UNO / no monitor window: TEPARDUINO.DLL, or click the UNO's USB
  port.
* The pop-up does not appear: click OPEN PANEL on the strip, or turn "Open the
  panel at Run" on its Settings page back on.

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/motor-driver-proteus-library

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

LICENCES AND THIRD-PARTY NOTES
* The magnet model (TEPMAGNET.DLL), the symbol and artwork and the Arduino
  Library V4.0 (ArduinoV4TEP.LIB / TEPARDUINO.DLL) are made by The Engineering
  Projects. The model is an independent implementation written from the
  typical data of 12 V 25 mm holding electromagnets. The models use only
  standard Windows libraries; no Visual C++ redistributable is needed.
  The C++ source code is not included. The demo's driver, our L9110S Motor
  Driver library (TEPL9110S.LIB / TEPL9110S.DLL), is a separate download.
* The demo's .hex 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 any magnet
  maker, 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\Magnet_Demo\Magnet_Demo.ino, select Arduino Uno
and use Sketch > Export Compiled Binary. The sketch needs 6,736 bytes of flash
(21 % of the UNO) and 289 bytes of RAM.

MODEL SCOPE AND LIMITS
Modelled: the coil (resistance with its temperature, an inductance that falls
as the plate leaves, the induced current when it does), the pull (the current
squared, the gap, the paint, the iron's saturation), the core's residual
magnetism (a hysteresis "play": a full current leaves about 2 N, a reverse
current of about a third clears it, a stronger one turns it over), the plate
and its load (held, falling, on the table), the coil's heat, the watch's
states and warnings.
How it runs: the coil is in the circuit as a backward-Euler companion on its
flux linkage over the analog step; the plate and the heat run in sub-steps of
at most 50 us between the analog points, which are held to 0.2 ms while the
coil carries current or the plate moves (0.5 ms at rest).
Not modelled: a plate that only partly covers the face, sideways (shear)
loads - a magnet holds far less sideways than straight down - eddy currents,
the plate's own thickness and steel grade.

VERSION
TEP 12V Holding Electromagnet library V1.0 (Oct 2026). Device ELECTROMAGNETTEP
(TEPMAGNET.LIB / TEPMAGNET.DLL). Demo sketch Magnet_Demo V1.0. Demo driver:
L9110SADVTEP (TEP L9110S Motor Driver library V1.0, a separate library). Demo
board: ARDUINO UNO V4.0 (TEP Arduino Library V4.0) with its built-in serial
monitor.