Hi..
In my following circuit my Triac (BTA16 and BTA12 tried both) dont get fully on. When my Main is 232VAC i get 160VAC from my triac. I also removed the gate resistor but it did not make any difference. Other than that my circuit works fine. My uC PC0, PC1 and PC2 reads 4.8V when ON.
Assuming that the Gnd vs Neutral issue has nothing to do with it, the next question is when does the MCU drive the port pin high relative to the zero crossing of the AC wave? If your gate drive routine has any internal delay, that would deliver only a partial half-cycle. Also, the ability of the MCU to source enough current to trigger the triac comes into question.
Because you don't have 220V connected to it - the 220V connects to the 'top end' of the load, and the triacs switch the 'bottom end' of the load to neutral.
I'm not an expert in triacs. But the circuit looks very strange to me. I've seen triacs driven with AC, but you use DC. Perhaps you (or someone else) can explain how it is supposed to work?
In the US, our line cords have three conductors: Black, called Line or L1, measures 120Vac with respect to earth, is a current carrying conductor that supplies power to the appliance. White, called Neutral, measures oVac with respect to earth , is a current carrying conductor that provides the return path to power the appliance. Green, called Ground or Gnd, measures oV with respect to earth, is not a current carrying conductor except if a fault occurs.
The use of Gnd in your schematic causes terrible confusion. Call it what it is: Neutral.
Assuming that the Gnd vs Neutral issue has nothing to do with it, the next question is when does the MCU drive the port pin high relative to the zero crossing of the AC wave? If your gate drive routine has any internal delay, that would deliver only a partial half-cycle. Also, the ability of the MCU to source enough current to trigger the triac comes into question.
Because you don't have 220V connected to it - the 220V connects to the 'top end' of the load, and the triacs switch the 'bottom end' of the load to neutral.
so i connected a small table fan which spins very slowly and also measured the VAC from the hot and neutral and got 160VAC and when the triac is off i get 0VAC.
so i connected a small table fan which spins very slowly and also measured the VAC from the hot and neutral and got 160VAC and when the triac is off i get 0VAC.
What is the timing between the trigger pulse from the uC to the gate pin of the triac and the AC sinewave?
What does the waveform look like on a scope?
What is the timing between the trigger pulse from the uC to the gate pin of the triac and the AC sinewave?
What does the waveform look like on a scope?
Point to a datasheet of the ATMEL part. You should never remove the resistor.
Your second schematic shows a 15 V supply, not 5.
What happens when you use 5V directly with a series resistor R <= (5-1.3)/10e-3 ohms.
Make sure that MT1 and MT2 aren't mixed up.
Most designs of this type might use an Opto triac and a triac for the larger loads. This keeps your 5V supply isolated from the line. Depending on your load, you can use a zero cross or random opto-triac. Zero cross is generally used to reduce interference.
I'm not an expert in triacs. But the circuit looks very strange to me. I've seen triacs driven with AC, but you use DC. Perhaps you (or someone else) can explain how it is supposed to work?
Most Triacs can be triggered by a DC voltage of either polarity. But the current required varies depending on which quadrant it is in at the moment. See this document for an explanation of the quadrants. https://www.littelfuse.com/~/media/...lding_of_SCRs_and_Triacs_Application_Note.pdf
See the individual data sheet for the triac you are using to get it's requirements.
Thank you very much Chris. I used triacs in few projects and I always used optocouplers to trigger them. I didn't know there was another way. Your documents provide a good explanation. I'll need to study them, and then, hopefully, I'll understand triacs better.
so i connected a small table fan which spins very slowly and also measured the VAC from the hot and neutral and got 160VAC and when the triac is off i get 0VAC.