SainSmart relay boards and the Due

I'd like to use the following relay board with the digital outputs on the Due: http://www.sainsmart.com/arduino/arduino-components/relays/4-channel-5v-relay-module-for-pic-arm-avr-dsp-arduino-msp430-ttl-logic.html

I've googled and heard both ways, i.e. some people say that 3.3V is not enough, others say it is, and the other part is that I can't find the input current for the optocoupler (and don't know what they are, typically). So, the question is, can I use the 3.3V digital pins with this board as is, or do I need additional circuitry? I was looking at a logic level converter, or just a resistor and transistor.

Thanks for the help.

Shouldn't be a problem. The device says a Raspberry Pi will work, and it is 3.3v logic.

Here is how to wire it up. It is a 8 channel, but the theory and parts are the same. https://docs.google.com/file/d/0B5-HND9HJkXWSTQtYlFTZ3VyODA/edit

SurferTim: Shouldn't be a problem. The device says a Raspberry Pi will work, and it is 3.3v logic.

Here is how to wire it up. It is a 8 channel, but the theory and parts are the same. https://docs.google.com/file/d/0B5-HND9HJkXWSTQtYlFTZ3VyODA/edit

Thanks, so it does need additional circuitry, i.e. 3.3V TTL isn't going to work directly with the optocoupler.

Yes, it needs a transistor and a couple resistors for each relay.

Actually no, you do not need to buffer the outputs at all. you do not need a transistor circuit to drive this type relay set up. all you need to do is,

1; Note the jumper on the left side of the relay board as shown in the hookup diagram. Remove it. now you can use to independent power sources, that are totally isolated from each other.

2: connect the appropriate power supply "5V/12V", to the far left pin, where the jumper was. note: double check this on your relay board. Make sure it goes through the output transistor directly to the relays.

3: connect 3.3 V where the 5V power supply was connected.

4: if you're using independent power supplies make sure you connect the grounds to the appropriate pins. These pins can be tied together or totally independent for isolation purposes.

Now you can power the relays with 5V/12V, and use 3.3 V to power the input port. On my 12V relay board, which looks to be identical, Each relay Input draws .56 mA of current, At 3.3 V.

check it for yourself.

stay safe and have fun.

Check it for yourself. Make sure you remove the jumper first.

promacjoe: Actually no, you do not need to buffer the outputs at all. you do not need a transistor circuit to drive this type relay set up. all you need to do is,

1; Note the jumper on the left side of the relay board as shown in the hookup diagram. Remove it. now you can use to independent power sources, that are totally isolated from each other.

2: connect the appropriate power supply "5V/12V", to the far left pin, where the jumper was. note: double check this on your relay board. Make sure it goes through the output transistor directly to the relays.

3: connect 3.3 V where the 5V power supply was connected.

4: if you're using independent power supplies make sure you connect the grounds to the appropriate pins. These pins can be tied together or totally independent for isolation purposes.

Now you can power the relays with 5V/12V, and use 3.3 V to power the input port. On my 12V relay board, which looks to be identical, Each relay Input draws .56 mA of current, At 3.3 V.

check it for yourself.

stay safe and have fun.

Check it for yourself. Make sure you remove the jumper first.

Excellent, thank you!