Control relay (active low) without an transistor
Gone through the Sain smart relay module

The Board used two relay drivers ULN2083 (8 channel relay driver) instead of transistors to drive all 16 relays. 


and the 4pin component on each relay channel is an opto-isolator.



the pin 1 of opto-isolator is connected to VCC via a current limiting resistor and pin 2 to GPIO of controller (here arduino). when GPIO is high no current conduction hence relay will be "OFF" and when GPIO is LOW relay will be "ON".

Mostly when there is need to control multiple devices making GPIO's as sinking is the best approach.


  Is that a good way to do this?


Yes, no issues.