Light dimming using triac and optocoupler is very common and basic circuit, I have successfully tested the dimming for 1 channel (1 triac, 1 opto-coupler) now I want to add one more light dimmer with same MCU, whenever I start 2 channels (2 triac, 2 opto-couplers) circuit I have got fluctuation in one of the 2 channels.
I am giving trigger input to the NPN transistor from XMC1100 series micro-controller, I also have running ZCD circuit ref for my micro-controller, so there is no problem in input side.
I have also tried to implement an RC snubber circuit (R= 470E 1/4W and C=10nF 400v), but there is still fluctuations in one dimming channel.
(I want to make it clear that I have made 2 identical PCBs, For both the PCBs different channels have fluctuations, and other channel have perfect dimming output, also Ihave checked hardware multiple time. All the components are same value, I have also swapped triacs but same output.)
Here is my circuit component description:
- Triac = BT138-800
- Opto-coupler = MOC3021s-TA1 (SMD Version of MOC3021)
- NPN transisto = MMBT3904
- 3.3V VCC,230V AC Supply