Triac & Optopcoupler

Thread Starter

cheesemunger

Joined Jan 25, 2009
53
Ok,

I having trouble getting my head around this. Lets say I get
a MOC3010M or similar, what else do I need (minimum requirements) for AC control with a microcontroller such as an Arduino. I have been told I need another TRIAC but doesn't it have one inside??

Cheesemunger

 

Thread Starter

cheesemunger

Joined Jan 25, 2009
53
If I use that circuit to control the lights in my room can I use it to do dimming or just on/off. I think its on/off but I'm not sure.
 

bertus

Joined Apr 5, 2008
19,944
Hello,

With direct acting I mean, when the led in the optocoupler is activated the diac will trigger.
(this can be used as a dimmer).
With zero crossing I mean, when the led in the optocoupler is activated, the diac wil wait until the next zero crossing to be activated.
(this can be used as a switch only).

Greetings,
Bertus
 

bertus

Joined Apr 5, 2008
19,944
Hello,

The Q8016LH6 is a 16 A 800 Volts triac.
It needs 80 mA gate current.
The IL410 and IL420 can deliver 300 mA gatecurrent, so I expect it will work.

Greetings,
Bertus

Attached datasheet for the Q8016LH6
 

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Thread Starter

cheesemunger

Joined Jan 25, 2009
53
Alberto: In the circuit you posted, what are the capacitors and resistors for? Are they really needed?
 

Thread Starter

cheesemunger

Joined Jan 25, 2009
53
Ok so here is my maths to get my resistor value for IL410/IL430.

120 x 1.414 = 170 V, so R = 170 V / 3 A = 56 ohms minimum.

3 amp being the ITSM of the optocoupler
 

bertus

Joined Apr 5, 2008
19,944
Hello,

Here is a peace of text from the site alberto gave:

Line input voltage

The above discussion notes the input voltage also affects the resistor value. For 115 Vac, 100 or 180 ohms will work fine for most loads. The 180 is a little too high for a 24 Vac line to trigger the gate, and too low for a 220 Vac line for the opto peak current limit.

For 24 Vac line, the triac will turn on with the 100 ohm and 180 ohm resistors, but I think the initial turn-on cycle will be 'late', at 13 V max (but I think it stays on once turned on). A resistor value better suited is:
24 x 1.414 = 34 V, so R = 34 V / 1 A = 34 ohms minimum. Round to 33 ohms for a standard value.
The max triac turn-on voltage will be:
R x IGT + VGT + VTM = 33 ohms x 50 mA + 1.3 V + 3 V = 6.0 V.

For 220 Vac line (use 230 to be consistent with the 115 math):
230 x 1.414 = 325 V, so R = 325 V / 1 A = 325 ohms minimum. Round to 360 ohms for a standard value.
The max triac turn-on voltage will be:
R x IGT + VGT + VTM = 360 ohms x 50 mA + 1.3 V + 3 V = 22 V.
Greetings,
Bertus
 
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