Relay Shield with manual control

Hi everyone,

I glad to introduce one interesting Relay Shield to you.
![](http://www.elecrow.com/extent images/Elecrow Relay Shield2.png)
It has little difference with other relay shield, 4 white buttons are particular noticeable. Yes, these four buttons allow you to control 4 relays manually, give a special use feeling, it is very siut for newbie of electronic.
![](http://www.elecrow.com/extent images/Elecrow Relay Shield4.png)
Besides, its headers are used length headers, so it is extendible, you can plug other shield to it.

For detail please visit: Elecrow-Relay Shield.

Interesting,

What happens electrically if you press a button?
Does it short the Arduino Pin somehow?
is there an opto coupler used?

In short, can you post a schematic?

robtillaart:
Interesting,

What happens electrically if you press a button?
Does it short the Arduino Pin somehow?
is there an opto coupler used?

In short, can you post a schematic?

Manual switches work on the output side of the opto-isolator chip, so no effect/damage to an arduino output pin, it would just 'override' a arduino command to turn off the channel relay.

Schematic drawing:

Opto pin out drawing:


Lefty

Thanks Lefty,
Did not look hard enough :blush:

Would be nice if the switches were also behind an opto coupler so I could replace the switches with some external source that could override the Arduino.
Still I like the idea!