Jeremie - would you share the link to the relay board that we used on bimbo?

Here's the link: http://www.smartarduino.com/four-way-relay-development-board-with-led-indicator_p94631.html

One thing to note: The opto-couplers on this board activate with a low signal (0V).

*Edit: Oh and the VCC should be 5V. I don't believe 3.3V worked for me.

@Alan... I think It gets the 5V from the power pin (I use a couple with my inMoov using 6V and it is fine)... The signal pin is just the trigger (some sort of mosfet maybe?). Anyway 3,3V seems to do fine... I have been using these plug and play for a few years now in various projects with no issues... Come to think of it so has Steve G...

Oh, yeah, I didn't notice that they connect all three pins to the digital port, that makes sense. I guess if using with a 7.4 lipo would probably want to put a 5v regulator inline.

I am on my phone now so can't easily check, but I noticed in the data sheet download zip file that there was also a schematic. Should check to see if it has a mosfet or transistor on board.

Alan

So will the resistor work? Or is a diode in the signal line needed?

This is a picture of the relays I tried to use and had the same problem with it staying on. I put a 5 volt supply to it, and gnd to gnd on the ezb and the signal to a port.

I needed the relays to work for the project so I made a transistor switching board that Rich posted. That got me running. I don't have the spec sheet, there was none when I got it on ebay.

I know others had tried to make this style relay work, but I never heard a final fix.

I put a 10k ohm resistor in the signal line. It inverts the trigger method. I put power on, it turns off. I put digital off, it turns on.

Before it would only partially turn off, not enough to disengage it.

I won't be able to test it until late this week, but maybe a 10k resistor, sig to ground will fix it?