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The BT136-800E is a TRIAC (Triode for Alternating Current) that is used for controlling the flow of electrical power in AC (alternating current) circuits. Like other TRIACs, the BT136-800E is commonly employed in applications requiring the switching or modulation of AC loads, such as in light dimmers, motor speed controls, and heating systems. The BT136-800E is designed for use in circuits that handle higher voltages, as it is rated for 800V, which makes it suitable for applications in household and industrial power control systems.

Example: Use in a Light Dimmer Circuit

1. Input Control Signal: A control signal (such as from a microcontroller, potentiometer, or a phase control circuit) is applied to the gate of the BT136-800E.

2. Triggering the TRIAC: When the gate receives a trigger pulse, the TRIAC switches on, allowing current to flow between the MT1 (Main Terminal 1) and MT2 (Main Terminal 2).

3. Conducting AC Current: Once triggered, the TRIAC conducts current in both directions (positive and negative half-cycles of the AC signal). The TRIAC stays in the "on" state until the current through it drops to zero, which naturally happens during the zero-crossing point of the AC signal (the point where the current direction changes).

4. Controlling the Power: By adjusting the timing of the gate pulse, the amount of time the TRIAC is conducting can be controlled. This allows for modulation of the power delivered to the load (such as a lamp or motor). For example, if the TRIAC is triggered later in the AC cycle, less power is delivered, dimming the light or reducing motor speed.

Applications:

• Light Dimmers: The BT136-800E is widely used in dimmer switches to control the brightness of lights. By adjusting the trigger time (or phase angle), the amount of light produced can be controlled.
• Motor Speed Control: The TRIAC can be used in fan or motor speed control systems, where controlling the phase of the AC supply to the motor can change its speed.
• Heater Control: The BT136-800E can regulate the power supplied to heating elements, such as in electric stoves or room heaters.
• Solid-State Relays: In solid-state relay applications, the BT136-800E can switch AC loads without mechanical moving parts, offering faster switching and greater reliability.

Key Characteristics:

• Voltage Rating: The BT136-800E has a maximum voltage rating of 800V, which makes it suitable for applications in standard household AC voltage systems as well as in higher voltage applications (up to 800V AC).
• Current Rating: It can handle a maximum current of 4A, making it suitable for moderate power control applications like small motors, light dimming, and heating control.
• Gate Triggering: The gate terminal is used to trigger the TRIAC into conduction. The timing of this trigger pulse allows for precise control over when the TRIAC switches on within each AC cycle.
• Bidirectional Conductance: Since the TRIAC can conduct in both directions (positive and negative AC cycles), it is ideal for AC power control.

Working Principle:

• When a small current is applied to the gate (G), the TRIAC switches on, allowing current to flow between MT1 and MT2 (Main Terminals 1 and 2). Once on, the TRIAC remains conducting even after the gate signal is removed, until the current passes through zero (a natural phenomenon in AC circuits).
• The MT1 and MT2 terminals are connected to the AC supply and the load (e.g., a lamp, motor, or heater).

Example Circuit:

In a light dimmer, the BT136-800E TRIAC can be used in conjunction with a phase control circuit. By adjusting the timing of the gate pulse relative to the AC waveform, the circuit controls how much of the AC waveform is allowed to pass to the light, thus adjusting its brightness.