how do you use an SCR for full wave phase control?

I want to know what circuit to use in phase controlling of full wave circuits using SCR and how it is used in light dimming circuits.

5 Answers

  • Anonymous
    7 years ago
    Favorite Answer

    You can use a single SCR with a bridge rectifier to effect full wave control. The gate control will need to be isolated.

    Connect the SCR anode to + terminal of the bridge rectifier and the SCR cathode to the - terminal of the bridge rectifier. Connect the AC source to one of the AC inputs of the bridge rectifier and connect the load to the other AC terminal of the bridge rectifier. Use a photo isolated circuit to provide gate drive.

  • 7 years ago

    The SCR is in series with the load. the incomming voltage waveform is sensed. as the waveform crossed zero the SCR conducts the current until the voltage reachse a set point and the Scr shuts off until the next cycle begins, A full wave SCR has escentially two of them, one for each half of the cycle.

    There are many variations of this circuit.

    The lamp dimmer is the same and the power is the integration of the dutycycle.

  • fuzzy
    Lv 6
    7 years ago

    for full wave control (single phase) you need two SCRs or one Triac. Either way the voltage applied to the gate is dleayed by a varying amount so the triac/SCR is triggered earlier or later in the AC cycle.

    For more information Google triac trigger circuits

  • Steven
    Lv 7
    7 years ago

    Some very large dimmers actually use two SCRs but your basic dimmer is a triac, a diac, a capacitor and a potentiometer. The Diac remain hi-Z until some voltage builds on the capacitor, then fires into the triac gate. The delay to charge the cap depends on the pot resistance.

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  • 7 years ago


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