SMSCOM Twincontroller pro light sensor

A light sensor for the SMSCOM Twincontroller PRO MK2 in 4.5 and 7 amps. It lets your controller behave differently once your lamp goes off.

Why humidity climbs the moment the lights go out

This is the problem the sensor exists for, and it affects almost everyone controlling on temperature.

A controller looking only at temperature does exactly as asked at night: it is cooler, so the fans may drop back. Meanwhile something else is happening. The air cools, and cooler air holds less moisture. The same amount of water vapour then produces a far higher relative humidity.

So your extraction slows at precisely the moment you would want to move more air. That is the window mould gets its chance in, and it explains why flowering problems so often start at night while your daytime readings look fine.

With the light sensor your controller knows whether your lamp is on or off, and can behave differently during the dark period. That keeps enough air exchange overnight to carry moisture out rather than shutting it in.

It fits the PRO versions only. The standard MK2 does not have the input.

Technical Specifications:

• Fits: SMSCOM Twincontroller PRO MK2, 4.5 A and 7 A
• Function: distinguishes day from night, for different behaviour in the dark period
• Use: controlling humidity during the dark period

Frequently asked questions

Does it fit my standard Twincontroller MK2?
No, only the PRO versions. Those have the input for it.

Does it measure humidity?
No, it measures light. That tells the controller whether it is day or night, and that is what drives the behaviour.

Where should I put it?
Where it sees your grow lamp and no other light. Outside the tent or beside a doorway does not work reliably.

Do I need it if I already have a dehumidifier?
The risk is smaller then, but air exchange is still needed. The sensor stops your extraction dropping too far overnight.