TXS0108E problems with relays


look in picture below, I’ve connected it like this. Now it seems not all relays are working. I’ve measured it that output from TXS0108E are too weak. Its not 5v, its about 2,5v or 3v.

I used TXS0108E because i’ve read it from Relais - Let's Control It
that I can use level converter.

Is the output current from TXS0108E too weak? I do not understand because these relay trigger current needs only 2-4mA

12v to operate the coil?

not sure about this one. I'm not an electronics guru but I enjoy tinkering.

does the 12v share a GRD with the control circuit???

12volt coil power needs a return. Connect 12volt negative to the relay grounds.

A relay module with three input terminals also can't have opto isolation. Four terminals are needed fot that. Two for control and two for coil power. They still use an opto on this board (to fool noobs?). It is wise to avoid products marketed without a circuit diagram. Leo..

yes 12v is shared with ground, that is not the reason.

forgoden: yes 12v is shared with ground, that is not the reason.

Fritzing (as usual) doesn't show that.

Get us a circuit diagram of that relay module, or clear pictures of both sides of the board. Then we might be able to guess what the problem is.

Did you try moving the jumper (and inverted logic). Leo..

I’ve never seen that relay before… the above relay seems to be pretty popular and can have the high voltage ratings like the ones you posted.

also easier to have a 5v power for all of it instead of 5v then 12v then 110+ VAC


The text on that link: "each one needs 15-20mA Driver Current"


Each 5volt relay on that board uses ~80mA coil current, and 2mA drive current.

That board has the option for opto isolation, if you connect it right. Leo..

I don't really think that would be an issue. Obviously if you need a rely to control 110 then you'd use a power adapter and not batteries...

Use the arduino to control transistors for the coils and build a circuit to power the coils from the power adapter.

Thanks for hints. I've changed the jumper on all relays and then I used uln2803 instead TX0108E. No 5v to Common and it works.