Can't get the single-channel solid state relay module to trigger

I’ve purchased this 1 Channel Solid State Relay Module (DC Control, AC Load) | Core Electronics Australia

I’ve got a USB cable supplying 5v on the DC pins with a wire connecting DC+ and CH1 to trigger the relay when power is applied. A continuity test on the AC output says its open. If I remove the CH1 trigger to test the AC output is still open. I can’t work out how to get the relay to trigger.

According to the description " * CH1: Relay module signal trigger terminal (low level trigger is valid)". This means you need to apply a low level signal (0-2.5V) to the CH1 input in order to ‘trigger’ or close the relay. But you can’t just disconnect it to get a low level - it must be connected to ground.

Ahhh! Thank-you. The CH1 needed to be connected to DC- to work, not DC+

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Hi All
The link is a solid state relay. As such it is probably a “zero crossing” switching type which means it will only switch AC loads which is implied in the heading. But the relay data sheet makes no mention of this specifically. You cannot check the switching action with a DC load such as a multimeter. And there is no NO and NC contacts as with a mechanical relay, it is either ON or OFF.
Also there is a built in “snubber” circuit so if you are switching very light loads of only a few mA it will appear to never turn OFF.
Cheers Bob

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