TRIAC

[navid7i]

Can anyone tell me in the attached circuit why use always-on optotriac to drive TRIAC?

What is the purpose of using phototriac in the circuit?

This circuit is used to control the speed of ac motor and between pin 1 and 2 of CN2 is placed the RV1 (potentiometer).

Usually use phototriac for isolation but in this circuit, we don't need isolation. There is not a DC source or microcontroller for turning on the optotriac.

 

[Minder]

There is no isolation in the circuit shown, so no real point in using a Opto-isolator!!
Except to use the triac switching element in the TLP3035 isolator.

 

[navid7i]

There is no isolation in the circuit shown, so no real point in using a Opto-isolator!!
Except to use the triac switching element in the TLP3035 isolator.

Use for what purpose?

 

[Minder]

Use for what purpose?

What is the question?
I assume the opto was used for convenience as isolation reason can be disregarded.?

 

[bertus]

Hello,

@Minder , It looks like a circuit for some kind of soft start.
The circuit before the using C4 as time delay.
When the delay is over, resistor R10 is shorted to have higher power.

Bertus

 

[Minder]

Hello,

@Minder , It looks like a circuit for some kind of soft start.
The circuit before the using C4 as time delay.
When the delay is over, resistor R10 is shorted to have higher power.

Bertus

Probabally, but there is no isolation per-se.
As the OP asked what was the point of the opto.

 

[navid7i]

Hello,

@Minder , It looks like a circuit for some kind of soft start.
The circuit before the using C4 as time delay.
When the delay is over, resistor R10 is shorted to have higher power.

Bertus

Thanks for your answer.
It seems that you are right.Purpose of the use of Optotraiac is protection against inrush current.

 

[navid7i]

What is the question?
I assume the opto was used for convenience as isolation reason can be disregarded.?

It seems that the optotriac does not be used for isolation in this circuit.

 

[bertus]

Hello,

The optocoupler is probably used as a floating switch.

Bertus

 

[navid7i]

Hello,

The optocoupler is probably used as a floating switch.

Bertus

Hello
Can you explain in more detail?
I can not understand your point.
Thanks

 

[bertus]

Hello,

The transistor of the optocoupler is free from any potential, so it is basicaly used as a floating switch controlled by the led of the optocoupler.

Bertus

 

[navid7i]

Hello,

The transistor of the optocoupler is free from any potential, so it is basicaly used as a floating switch controlled by the led of the optocoupler.

Bertus

What is the purpose of the floating switch in this circuit??

 

[bertus]

Hello,

The output of the optocoupler is shorting R10 when activated.
Shorting R10 changed the timing of the triac, giving more power on its output.

Bertus

 

[navid7i]

Hello,

The output of the optocoupler is shorting R10 when activated.
Shorting R10 changed the timing of the triac, giving more power on its output.

Bertus

The output of optocoupler is activated always.

 

[bertus]

Hello,

The optocoupler is off at the moment of startup.
R6 and C4 are the time elements.
When C4 gets charged enough, the optocoupler is activated.

Bertus

 

[navid7i]

Hello,

The optocoupler is off at the moment of startup.
R6 and C4 are the time elements.
When C4 gets charged enough, the optocoupler is activated.

Bertus

Thanks.