I have a BTA12-600B Triac and an Arduino.

Is it possible I can trigger both positive and negative amplitudes of an AC cycle by suppling only a positive voltage from the Arduino digital pin to the Triac's gate terminal at the right time and moment?

Basically driving the Triac via the Arduino. The Arduino will supply the proper timing positive voltage to the gate pin with reference to a zero cross detection circuit.

It is possible to drive the Triac properly only using the Q1 and Q4 quadrants? Since Q1 and Q4 quadrants can use a positive voltage on it's gate pin?

  • \$\begingroup\$ robotdyn.com/… \$\endgroup\$
    – Juraj
    May 23, 2021 at 9:42
  • \$\begingroup\$ Thanks, useful link. But I was hoping to design my own PCB implementing this VFD technology which uses custom built Triac driver. \$\endgroup\$
    – S To
    May 24, 2021 at 10:42
  • \$\begingroup\$ there is a schematic for the module. it uses BTA16 - 600B. I have Arduino code for Triac control developed with this Triac module \$\endgroup\$
    – Juraj
    May 24, 2021 at 11:19

1 Answer 1


Yes, it's possible and should work OK but the whole circuit must be considered live.

Table 3 of the BTA12 datasheet states that for a "Standard triac" IGT is 25 to 50 mA for quadrants I - II - III and 50 to 100 mA for quadrant IV at VD = 12 V, RL = 30 Ω. @Spehro says that the -600B is not rated for quadrant IV switching. I'd believe him but I can't see it in the datasheet.

A major concern is that you might be considering driving a mains triac directly from the microcontroller and that the it's ground will now be referenced to mains voltage and must be considered live. This in turn means that you must ensure that the whole device including USB port is isolated properly and you can't connect to a laptop, etc., for serial port debugging, etc.

There is really no need to skimp on safety. An opto-triac provides the required level of isolation for, probably, 50c or so. There are plenty of application notes for the MOC series of opto-triacs and plenty of sample circuits on this site.

enter image description here

Figure 1. A sample opto-triac control. Image source: Electronics Tutorials.

You'll find more information in the MOC 3020 datasheet.

  • Use the MOC 3020 if you want to be able to dim a load using phase-angle control.
  • Use the MOC 3041 if you want on-off control at zero-cross to minimise EMI (electro-magnetic interference).
  • \$\begingroup\$ Thank You for your reply. Yes it does seem the 600B Triac is able to work on all 4 quadrants. Only special Triacs such as 3Q Triacs only functions from I-IV quadrants. Thanks for the dangers involved with the common mains grounding, specially with the USB. I am well aware and careful about it. I will be using homemade optocouplers made from infrared and phototransistor LEDs. The only reason why I would like build the Triac driver circuit from complete scratch is due to pure educational purposes. Like making your own sandwich, if you know what mean :) \$\endgroup\$
    – S To
    May 22, 2021 at 17:39
  • \$\begingroup\$ I think you're correct +1. I only saw table 2 for logic level. It's rated for QIV if you don't mind the double gate current. Negative drive is preferable for unipolar gate drive since the current is lower. \$\endgroup\$ May 22, 2021 at 17:58
  • \$\begingroup\$ How would it be possible to drive the Triac using an optocoupler and making a custom made circuit? There will be two optocouplers, one for the zero cross detection and another for the firing of the Triac. \$\endgroup\$
    – S To
    May 22, 2021 at 18:42
  • \$\begingroup\$ See the update. \$\endgroup\$
    – Transistor
    May 22, 2021 at 19:05
  • \$\begingroup\$ Thank You for the schematic, is it possible you have a schematic for building an actual component of a "MOC 3020"? \$\endgroup\$
    – S To
    May 22, 2021 at 19:11

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