flickering when two drivers operate adjascent

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With the guidance of RDR195 we designed a 20W dimmable driver with 40V/500Ma output and 230V input. It is working fine with a 230 v fan dimmers  available in India. But when we run two drivers simultaneously( each driver has seperate dimmer) both driver output leds are flickering at below 260 mA region. We need to adjust the output from 500Ma to 100mA.  But flicker starts at 260mA and below that  leds are going flicker and off. If one driver is operatiing alone dimming is very smooth from 500mA to 100mA.

Circuit is same as rdr195 except   transformer- is  PQ2620. Bias voltage is 28V. What could be wrong. Kindly guide us to solve the issue.





Please check the characteristics of the input voltage/current. Does the other dimmer distort the main supply? If the main supply is getting distorted, then it is possible that the erratic input supply variation is causing the flicker. The device won't be able to address this condition. Increasing the output cap and C3 could minimize the shimmer

It is also possible that with this configuration, there is more ringing and causes the triac to turn-off prematurely. This causes flicker due to multi-firing of the triac. Increasing R16 provides more damping and might help as well.