What is a DIAC? How DIACs Work? (DIAC Tutorial)

00:04:28
https://www.youtube.com/watch?v=SS31aVOziH0

概要

TLDRThe video provides a comprehensive explanation of the DIAC, focusing on its structure, operation, and applications in AC circuits like dimmers and motor controls. It describes DIACs as two-pin devices that allow alternating current to pass once a breakdown voltage is achieved, detailing how they work in conjunction with TRIACs and capacitors. It illustrates the functioning of a timer circuit and emphasizes the importance of using non-polarity capacitors in such applications. The video concludes with an invitation to the next lesson while ensuring viewers understand the critical role DIACs play in power electronics.

収穫

  • 🔌 DIAC stands for Diode for Alternating Current.
  • 💡 Used in AC timer and dimmer circuits.
  • ⚡ Allows bidirectional current flow.
  • 📊 Breakdown voltage typically 25-40V.
  • 🔋 Requires non-polarity capacitors.
  • 🛠️ Works with TRIAC to control current.
  • 🔄 Operates in both positive and negative cycles.
  • 📈 Capacitor charges until breaking voltage.
  • 🕰️ Essential for motor speed control applications.
  • ✅ Important to choose components based on datasheet information.

タイムライン

  • 00:00:00 - 00:04:28

    In this segment, the speaker introduces the concept of DIAC, a power electronics component used in AC applications such as timer circuits and motor speed control. The DIAC, an abbreviation for Diode for Alternating Current, has a two-pin configuration referred to as MT1 and MT2 or Anode-1 and Anode-2. The internal structure of DIAC consists of two diode structures connected in reverse parallel, allowing bi-directional current flow, making it highly suitable for AC applications. A voltage-current graph illustrates that DIACs do not conduct current until a breakdown voltage of 25-40V is reached, at which point they conduct in both the positive and negative cycles of AC. The speaker also explains a timer circuit example using a TRIAC, DIAC, non-polar capacitor, and lamp, describing how the current charging process in the capacitor leads to the triggering of the TRIAC and illuminating the lamp after reaching the breakdown voltage.

マインドマップ

ビデオQ&A

  • What does DIAC stand for?

    DIAC stands for Diode for Alternating Current.

  • In what applications are DIACs commonly used?

    DIACs are commonly used in AC timer circuits, dimmer circuits, and motor speed control circuits.

  • What is the breakdown voltage range for DIACs?

    The breakdown voltage range for DIACs is typically between 25-40V.

  • Can DIACs conduct current in both directions?

    Yes, DIACs allow bidirectional current flow.

  • What type of capacitor is recommended for use with DIACs?

    A non-polarity capacitor is recommended for use with DIACs.

  • What happens when the capacitor voltage reaches the breakdown voltage of a DIAC?

    When the capacitor voltage reaches the breakdown voltage, the DIAC starts to conduct current and triggers the TRIAC.

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  • 00:00:00
    Hi guys!
  • 00:00:01
    In our previous lessons, I examined  the working principle of Thyristor and TRIAC.
  • 00:00:07
    In this video, I will basically explain the working  principle of the DIAC, which is one of the power
  • 00:00:13
    electronics circuit elements used in AC timer,  also known as dimmer circuits and motor speed
  • 00:00:19
    control circuits, together with the TRIAC.
  • 00:00:22
    The abbreviation DIAC is used as an abbreviation of the English Diode for Alternating Current.
  • 00:00:28
    It is understood from its English name that this  two-pin power electronics circuit element is used in alternating current.
  • 00:00:35
    You see the shape of a  DIAC on the left and its symbol on the right.
  • 00:00:39
    They are generally blue in color.
  • 00:00:41
    DIACs have two pins.
  • 00:00:43
    One of them is MT1, which is the abbreviation  of Main Terminal 1 and
  • 00:00:48
    the other is MT2, which  is the abbreviation of Main Terminal 2.
  • 00:00:54
    In the  symbol, the pin names are as you can see on the right.
  • 00:00:57
    Instead of MT1 and MT2, you may encounter  the use of naming as Anode-1 and Anode-2 in some sources.
  • 00:01:06
    When we look at the internal structure of  the symbol, we can see that DIACs consist of two
  • 00:01:11
    diode symbols connected in reverse in parallel in  this way. In its physical structure, it consists
  • 00:01:18
    of two types of structures in the form of PNPN  connected in parallel.
  • 00:01:24
    Thanks to this structure,  DIACs allow two-way current flow.
  • 00:01:28
    As such, it is mostly preferred in AC applications.
  • 00:01:31
    It is useful to look at the working graph to better  understand the working logic.
  • 00:01:36
    Voltage-Current graph of DIAC is like this. From this graph, we can see that it works both ways.
  • 00:01:43
    DIACs normally don’t conduct current.
  • 00:01:46
    When a certain breakdown voltage is provided, they start to flow current.
  • 00:01:50
    Although this breakdown voltage varies according  to the DIAC type, it is in the range of 25-40V.
  • 00:01:56
    When this breakdown voltage is provided, they  start to flow current.
  • 00:02:00
    It works in the positive half cycle of AC in the forward polarity region,
  • 00:02:05
    while it operates in the negative half cycle of AC in the reverse polarity region.
  • 00:02:09
    So, the way it  works in both directions is the same.
  • 00:02:13
    Only the direction of the current is different.
  • 00:02:16
    To better understand the working principle, we can look at an example of a timer circuit.
  • 00:02:21
    As in our previous lessons, I showed the current directions according to the conventional current direction.
  • 00:02:27
    Here you see a timer circuit consisting of TRIAC, DIAC,  nonpolar capacitor and lamp.
  • 00:02:34
    There is also an AC source. In this circuit, during the positive half cycle of the AC sine wave,
  • 00:02:40
    the current allows the capacitor to charge by following the path I have shown with the arrows.
  • 00:02:45
    I want you to pay  attention to the (+) and (-) polarity values on the capacitor pins.
  • 00:02:51
    When the capacitor voltage  reaches the breaking voltage level of the DIAC,
  • 00:02:55
    for example 30V, the DIAC starts to flow current  and triggers the TRIAC from the gate pin.
  • 00:03:02
    When the TRIAC is triggered, current starts to flow  through the lamp and the lamp lights up.
  • 00:03:07
    Then  the lamp goes out again at the zero point of  the alternating current.
  • 00:03:11
    When switching to the during the negative half cycle of the AC sine wave, the current again follows the path I have
  • 00:03:17
    shown with the arrows, allowing the capacitor  to charge. When the breakdown voltage level is
  • 00:03:22
    reached again, the DIAC starts to pass current  and the TRIAC is triggered.
  • 00:03:27
    Thus, the current passes through the lamp and the lamp gives light.
  • 00:03:31
    Thus, after a certain breaking voltage level, DIAC turns on and offers bidirectional switching.
  • 00:03:38
    Here we have seen that the DIAC passes bidirectional current.
  • 00:03:42
    It is generally used with capacitors  as here.
  • 00:03:45
    In addition, the capacitor used here  should be a non-polarity capacitor in particular.
  • 00:03:51
    Because there is AC here, the capacitor must be used in both directions.
  • 00:03:56
    In this example circuit, I didn’t give the values of the circuit elements.
  • 00:04:00
    If you want to try the circuit,  you need to choose it by looking at the datasheet
  • 00:04:04
    information of the circuit elements according  to the magnitude of the AC voltage you use.
  • 00:04:09
    The working principle of DIAC, which is one  of the power electronics circuit elements
  • 00:04:14
    used in AC timer dimmer and motor speed control  circuits, generally together with TRIAC is like this.
  • 00:04:21
    I hope this video was helpful and you liked it.
  • 00:04:24
    Hope to see you in the next lesson.
  • 00:04:26
    Goodbye.
タグ
  • DIAC
  • TRIAC
  • AC circuits
  • timer circuits
  • motor speed control
  • breakdown voltage
  • bidirectional current
  • non-polarity capacitor
  • power electronics
  • dimmer circuits