Control Out of a Triac with PIC

[ertan2002]

Hi everyone, I am new here..

Well... I have a project which I need to control a machine with pic. And I am so confused for it. I really dont know what I can do ..

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Well I will control an AC system and I think relays are not enough because of high current.. Then as my lecturer said, I need to use a triac but I need some kind of pulse? But I will trigger triac with DC .. and I dont have many information about it then realyl i am so confused..
is possible to tirgger a triac with DC and control AC ? and which picture looks better (above) ?

Thank you

 

[nandhu015]

All the above circuits will work fine.

Read the datasheets of the components you are going to use.

What kind of load you are going to use? Resistive or Inductive..

 

[ertan2002]

thank you for reply..

loads are inductive. some loads are pressing machines and boilers which starts machines..

and i am curious that I need to use pic RA2 .. It will be special one or just logic 1 or logic 0?.. I mean that special is like pwm or interrupt ...

 

[nxt_]

To control an Ac system. u'll need first to detect the zero crossing of the 50HZ and then start to modulate the signal with the desired o/p.
many pic uc got built in clamp circuits . so you can connect the 220v directly through high oh-mic resistance maybe 3Mohm, or more (calculate it V=IR, ) to an interrupt pin to determine when the zero crossing occurs. and then start ur pulse width modulation and i recommend to do so through a dedicated pwm pin because such pins are work in the background. which means that you can enable it and do whatever you want in the code.

Here is an application note for the zerocrossing

h**p://ww1.microchip.com/downloads/en/appnotes/00521c.pdf

 

[ertan2002]

thanx for reply, but I will trigger geyt with DC .. But I will control AC load.. Then the zero crossing is not necessary for me ! ? Can I use moc?

 

[milind.a.kulkarni]

AC load control many times require the control in the half cycle range based .....the starting of the half cycle will be zero-crossing position so it will be good that your micro-controller will should know the zero-crossing postion of AC wave form....

Good Luck

 

[nandhu015]

thank you for reply..

loads are inductive. some loads are pressing machines and boilers which starts machines..

and i am curious that I need to use pic RA2 .. It will be special one or just logic 1 or logic 0?.. I mean that special is like pwm or interrupt ...

For Inductive loads the first circuit is best suited.

 

[ertan2002]

thanx friends, We decided that to use solid state relays