Suitable alternative to sugar cube relays.

After working with so many relay modules, be it an 8 channel module or a 4 channel one. Or a single channel one. The problem with EMRs is that they are really big for home automation products. I have made commercial solutions incorporating arduino nano which are really cost effective. But the problem is how do i bring the size of the whole module down where relays take up a lot of space.

Alternative that I would like to suggest:

1) SSRs ( really expensive)

2) BTA16 with MOC 3021.

You are perhaps wanting reed relays or signal relays? In general the amount of voltage
and power you are switching determines the size of the relay. High voltage high power DC
is the hardest, which is why a lot of mains relays are only rated to 28Vdc or similar.

So are you switching mains?

MarkT: So are you switching mains?

Exactly I am switching mains 240V AC just turning on/off lights and fans. SPDT operation is required just in one case rest SPST will do. But I cant find small relays.

Mains relays are not small because they have to handle mains. Several kV minimum isolation and the requirement to extinguish a 240Vac arc takes a certain amount of space (except for in a vacuum, but reed-relays are only rated to several 100mA or so).

Miniature mains SSRs are quite expensive.

MrJkComedy: 1) SSRs ( really expensive)

A common Omron 2Amp SSR is about $1 (shipped) on ebay. Leo..

A lot of nominally small loads have a high inrush (eg incandescant bulbs) , so 2A may not be sufficient.

Allan

The G3MB-202P I was talking about has a 30Amp 1-cycle rating. Leo..

I might buy a few - look handy....

Allan.

MrJkComedy: Exactly I am switching mains 240V AC just turning on/off lights and fans. SPDT operation is required just in one case rest SPST will do. But I cant find small relays.

What lights? What fans?

Maybe invest 30 bucks in a rollershutter controller and take it apart. Those switch L to L1, L2, off. I down know if they use logic to avoid L -> L1+L2 or an SPDT relay, but it should give you an idea. Anyway, they manage to switch not insignificant powers with considerable voltage spikes (as I learned the hard way, recently) on quite small room.