Project Files of SCR and TRIAC Library for Proteus: BT151, BT136

SCR AND TRIAC LIBRARY FOR PROTEUS - V1.0 (the BT151 SCR and the BT136 triac with their latch, 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/scr-and-triac-library-for-proteus.html
Report a bug or suggest a feature (our forum):
  https://www.theengineeringprojects.com/forum/category/scr-triac-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 bulbs are our own filament bulbs (included):
  https://www.theengineeringprojects.com/2026/11/filament-bulb-library-for-proteus.html
the zero-crossing detector our own PC817 and 1N4007 (included):
  https://www.theengineeringprojects.com/2026/11/pc817-optocoupler-library-for-proteus.html
and the SCR's switch our own IRLZ44N MOSFET (included):
  https://www.theengineeringprojects.com/2026/11/n-mosfet-library-for-proteus.html
Support us (the libraries are free):
  https://www.theengineeringprojects.com/donate

FILE STRUCTURE
SCR-and-TRIAC-TEP-v1.0/
|-- Proteus Library Files/
|   |-- ArduinoV4TEP.LIB                              201.9 KB   TEP Arduino boards V4.0 (UNO) -> LIBRARY
|   |-- TEP1N4007.LIB                                   9.7 KB   a part the demo uses -> LIBRARY folder
|   |-- TEPBULB.LIB                                    17.7 KB   a part the demo uses -> LIBRARY folder
|   |-- TEPNMOS.LIB                                    17.9 KB   a part the demo uses -> LIBRARY folder
|   |-- TEPOPTO.LIB                                    30.0 KB   a part the demo uses -> LIBRARY folder
|   |-- TEPRESISTOR.LIB                               306.9 KB   a part the demo uses -> LIBRARY folder
|   |-- TEPTHYR.LIB                                    15.1 KB   the library -> LIBRARY folder
|-- Proteus Model Files/
|   |-- TEP1N4007.DLL                                 286.5 KB   its model -> MODELS folder
|   |-- TEPARDUINO.DLL                                883.5 KB   the Arduino board model -> MODELS folder
|   |-- TEPBULB.DLL                                   291.0 KB   its model -> MODELS folder
|   |-- TEPNMOS.DLL                                   295.0 KB   its model -> MODELS folder
|   |-- TEPOPTO.DLL                                   306.0 KB   its model -> MODELS folder
|   |-- TEPRESISTOR.DLL                               311.0 KB   its model -> MODELS folder
|   |-- TEPTHYR.DLL                                   306.5 KB   the model -> MODELS folder
|-- Proteus Simulation/
|   |-- SCR-and-TRIAC-ArduinoUnoV4.pdsprj              27.4 KB   the demo project
|   |-- TEP1N4007.DLL                                 286.5 KB   copy of its model
|   |-- TEPARDUINO.DLL                                883.5 KB   copy of the board model
|   |-- TEPBULB.DLL                                   291.0 KB   copy of its model
|   |-- TEPNMOS.DLL                                   295.0 KB   copy of its model
|   |-- TEPOPTO.DLL                                   306.0 KB   copy of its model
|   |-- TEPRESISTOR.DLL                               311.0 KB   copy of its model
|   |-- TEPTHYR.DLL                                   306.5 KB   copy of the model
|   |-- Thyristor_Demo.hex                             16.6 KB   the demo firmware
|-- Arduino Code/
|   |-- Thyristor_Demo/Thyristor_Demo.ino               4.3 KB   the demo sketch (source of the .hex)
|-- README.txt                                        ~14.6 KB   this file
Total: 5.88 MB (unzipped). The C++ source code of the models is not included.

WHAT IS IT?
Two thyristors in the TO-220 package, drawn at true scale (the black body, the metal tab with its
hole, three legs 2.54 mm apart):
  * BT151-500R - an SCR, 500 V, 12 A. Pins 1 K, 2 A, 3 G; the tab is A.
  * BT136-600E - a sensitive-gate triac, 600 V, 4 A. Pins 1 T1, 2 T2, 3 G; the tab is T2.
  * One analog model with the datasheet values (Philips BT151, NXP BT136-600E): the gate junction;
    the latch - it fires once the gate current
    passes IGT (the triac's in each of its four quadrants), latches once the main current passes IL
    and stays on until the current falls under
    IH; the on-state (about 1 V plus a series resistance); breakover past its rated voltage; the
    heat from the junction through the tab and the
    heatsink (a property: NONE, SMALL or LARGE) to the air. IGT, IL and IH fall as the junction
    warms.
  * The triac measures its own firing angle from the zero of the voltage across it, and the share of
    full power a resistive load gets.
  * Click one at Run for the pop-up: the part and its symbol lit while it conducts, the latch with
    its currents (SCR) or a scope of the last two
    cycles with the quadrants (triac), 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.

TWO DEVICES (search "BT1" in Pick Devices):
  SCRBT151TEP     "BT151 SCR V1.0" in TEPTHYR.LIB (Thyristors > SCRs), prefix Q, model TEPTHYR.DLL.
  Pins K, A, G.
  TRIACBT136TEP   "BT136 Triac V1.0" in TEPTHYR.LIB (Thyristors > Triacs), prefix Q, model
  TEPTHYR.DLL. Pins T1, T2, G.

THE POP-UP
Click the part at Run. Tabs:
    Thyristor  the part with its tab warming and its symbol, lit while it conducts; the SCR: a scope
    of the last 2 s (V A-K, the anode current,
               the gate) and the anode current on a scale against IH and IL; the triac: a scope of
               the last 40 ms (the voltage across it and its
               current), the four quadrants with the ones it fired in, the firing angle and the
               load's share of power; eight live values.
               The toolbar: New part, the ratings, the pins and the heatsink.
    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; the triac fires a set delay after each zero of the AC
    (found by the PC817) and the SCR's steps run by
    the clock; the sketch prints each step and, every second, the triac's delay and the SCR's anode
    voltage.
  * Q1 (BT136-600E triac, 21 W bulb on 12 V AC): fired 1.98 ms after each zero (36 deg, about 95 %
    of full power) from 0.5 s, 4.99 ms (90 deg,
    about 50 %) from 3.5 s and 7.99 ms (144 deg, about 5 %) from 6.5 s - the pop-up's own
    measurement against the sketch's 2, 5 and 8 ms; about
    100 firings a second, in Q1 (T2+ G+) and Q4 (T2- G+) with 17.6 mA on the gate; it turned off at
    every zero of its current. 1.48 W at 2 ms
    (junction heading for 117 C on the bare tab), 0.35 W at 8 ms.
  * Q2 (BT151 SCR, 5 W bulb on 12 V DC): a 1 ms gate pulse of 12.4 mA at 1 s fired it and it latched
    (5.3 A at that moment - the cold filament -
    then 402 mA at 0.81 V); Q3 shorted it for 20 ms at 5 s, its current fell under the 6.9 mA
    holding current and it turned off, blocking 12 V;
    fired again at 8 s, latched again. The monitor read the anode at 0.81 V while on, 12.01 V while
    off.
  * The pop-up: Thyristor (the part and its symbol; the SCR's latch with its currents and a 2 s
    scope; the triac's 40 ms scope, quadrants and
    firing angle), Graphs, Event log, Check - all four pages followed the run, for both parts.

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" (TEPTHYR.LIB, TEPRESISTOR.LIB, TEPNMOS.LIB,
TEPBULB.LIB, TEPOPTO.LIB, TEP1N4007.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 TEPTHYR.DLL, TEPRESISTOR.DLL, TEPNMOS.DLL, TEPBULB.DLL, TEPOPTO.DLL, TEP1N4007.DLL and
TEPARDUINO.DLL from "Proteus Model Files" to the MODELS folder (...\Proteus 8 Professional\MODELS).
4. Delete TEPTHYR.IDX from the LIBRARY folder if it is there (Proteus makes a new index).
5. Start Proteus. In Pick Devices (P) search "BT1".

RUN THE DEMO
"Proteus Simulation\SCR-and-TRIAC-ArduinoUnoV4.pdsprj" (an A4 sheet) - keep the .hex file and the
DLLs beside the project.
  ARD1:   Arduino UNO V4.0 running Thyristor_Demo.hex, its serial monitor built in (window "TEP
  Arduino UNO - ARD1").
  The dimmer:  V1 (Proteus's ALTERNATOR, 12 V rms, 50 Hz) - L1 P21W - Q1 BT136 T2, T1 to GND; D9 -
  R1 220 - gate
               zero-cross: AC - R2 2k2 - U1 PC817 LED, D1 1N4007 across it; U1's output to D2
               (INPUT_PULLUP)
  The latch:   +12V - L2 W5W - Q2 BT151 A, K to GND; D10 - R3 330 - gate; Q3 IRLZ44N across Q2 (D11
  - R4 220 - gate); R5 / R6 20k / 10k to A0
  1. Press Run. The triac fires 2 ms after each zero, then 5 ms (3.5 s), then 8 ms (6.5 s): L1
  bright, half, dim.
  2. The SCR fires at 1 s and latches; Q3 shorts it at 5 s and it turns off; it fires again at 8 s.
Closed the monitor? Click the UNO's USB port.

WIRING (the same in Proteus and on a real board)
  SCR:    load from the supply to A, K to GND; gate from a pin through 330 ohm; to turn it off on
  DC, short it or break the circuit
  triac:  load from the AC to T2, T1 to the AC's return; gate from a pin through 220 ohm (T1 is the
  gate's reference); on the mains: an opto-triac
REAL HARDWARE:
 * The mains can kill: isolate the controller (an opto-triac such as the MOC3021), fuse the load,
   and have the build checked.
 * Size the gate drive for the worst part and the worst quadrant: 15 mA for the BT151, 25 mA for the
   BT136-600E in Q4.
 * About 1 W of heat per amp; the tab is live (A or T2) - insulate it from a shared heatsink.
 * Cold lamps and motors draw many times their running current at switch-on.
 * Inductive loads need a snubber (R and C) across the triac.

THE DEMO SKETCH ON THE SERIAL MONITOR (Thyristor_Demo V1.0, 9600 baud)
There are no commands. The sketch fires the triac a set delay after each zero and runs the SCR's
steps by the clock.
EXPECTED MONITOR OUTPUT
  SCR and TRIAC - The Engineering Projects
  t=1 s: SCR gate pulse, 1 ms

PROPERTIES (double-click the part > Edit Properties)
  Part (VALUE)                     the label: BT151 or BT136 (the device sets the part)
  Heatsink                         NONE (the bare tab: about 60 C/W to the air in all), SMALL (15
  C/W from the tab), LARGE (5 C/W)
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 TEPTHYR.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
* It never fires: the gate current is under IGT, or there is no voltage across it.
* DID NOT LATCH: under the latching current when the gate pulse ended - a longer pulse or a heavier
  load.
* It will not turn off on DC: its current must fall under the holding current - break, short or
  reverse it.
* The dimmer flickers: the gate pulses are late or missing - keep the sketch's loop free of waits.
* The part is not simulated: TEPTHYR.DLL is missing from MODELS and from the project folder.
* The part is not simulated: TEPTHYR.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/scr-triac-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 (TEPTHYR.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\Thyristor_Demo\Thyristor_Demo.ino, select Arduino Uno and use Sketch > Export Compiled
Binary. Replace the simulation's .hex with the exported HEX. The sketch needs 6,022 bytes of flash
and 227 bytes of RAM.

MODEL SCOPE AND LIMITS
Modelled: the gate junction, IGT per quadrant, IL, IH and their fall with temperature, the latch and
the turn-off under IH, the on-state, breakover,
the heat path junction - tab - air.
Not modelled: the 2 us turn-on and the turn-off time, dV/dt firing, the triac's commutation limits.
The heatsink values are typical.

VERSION
TEP SCR and TRIAC library V1.0 (Nov 2026). Devices SCRBT151TEP and TRIACBT136TEP (TEPTHYR.LIB /
TEPTHYR.DLL). Demo sketch Thyristor_Demo V1.0. Demo board: ARDUINO UNO V4.0 (TEP Arduino Library
V4.0) with its built-in serial monitor.