Hi Everyone,

I'm trying to use this relay board in my project and have accidentally gotten it to work, but would like to confirm that I'm not damaging my Netduino if I leave my current configuration alone.

I'm using the following relay board:

http://www.sainsmart...-ttl-logic.html

Basically here's the process I followed:

1. Wired the 3.3V output of the Netduino to the 5V of the relay board's input (I read that this should be enough voltage to trigger the relays)

2. Wired the GND to GND, and desired outputs to the desired relay board's inputs

3. Wrote up the code.

4. Plugged in the Netduino through USB and powered the relay board only to find the LED on the Netduino flashing weirdly (seemed like it was in some type of error state).

5. Unplugged the Netduino USB and reset and discovered that all of a sudden my code was working and the relays were switching

It appears I made a false assumption that the relay boards inputs were isolated from its power supply and that the relay board is somehow powering the Netduino.

So I'm just wondering if this is bad for the Netduino, meaning that I should wire together some opto-isolators (or a shift register [color=rgb(40,40,40);font-family:helvetica, arial, sans-serif;]74HC595? can anyone confirm that this would isolate the Netduino?) to properly isolate the Netduino.[/color]

[color=rgb(40,40,40);font-family:helvetica, arial, sans-serif;]Thanks[/color]

Just to touch base.

I put together a breadboard circuit with two resistors, a diode, and an opto-isolator (total cost ~$2).

Works great!

Thanks again for the replies.

Thank you for the replies.

I'm thinking that Opto-Insulator might be my simplest and easiest best.  Is there an input opto-insulator breakout board out there?  Or should I just get a MakerShield and put it (opto-insulator or voltage divider) together myself?

Hi Everyone,

I'm working on automating a sheep drafting setup for my family farm and believe that Netduino is going to be the right way to go.

For detecting the animals, I have purchased a SICK Photoelectric sensor, VTE180-2P42442 that is four wire (capable of NPN or PNP) but I am not sure how to wire it to my Netduino for PNP.

I have attached the datasheet for the sensor.  My main concern is that this sensor requires 10-30V to operate and the netduino is only capable of 5V.  Do I also need an instrumentation amplifier since the max current output is 100mA?

Any help or advice would be greatly appreciated.

Thank you