is it okey to use a triac as light dimmer without a diac on its gate?

 

You need something to control the triggering of the triac to effect dimming.
Triac dimmers operating on AC use phase control to adjust the power delivered to the load,
that's what the diac does in the circuit, along with the RC network.

So no, it won't work without a diac.

 

A diac is just two 30V zener diodes back to back, it ensures that the capacitor charges upto approx 27V then it fires the triac.

 

A diac is just two 30V zener diodes back to back, it ensures that the capacitor charges upto approx 27V then it fires the triac.

This is an incorrect statement. While it is true they both will not conduct until a breakdown voltage is reached, this is where the similarities end. A zener diode will stay at the breakdown voltage, the Diacs voltage will drop. It kind of acts like a spark plug.

https://en.wikipedia.org/wiki/DIAC

 

In the past i made i dimmer using two zeners and it worked just as well, its better to use it with the diac as its designed for that purpose.

 

In the past i made i dimmer using two zeners and it worked just as well, its better to use it with the diac as its designed for that purpose.

Thank you sir. Can you please show me a diagram using zener diode instead of diac so that I can perform it easily.