Midi Input

[Grumpy_Mike]

So either a faulty opto or not wired like you think. Like the bread board is not making good connections.

[Chole]

I got a pack of 1o optoisolators and even though I tried replacing them before, this time it worked. Led on pin 13 flickers even if no key is pressed just like the test probe but when I press a key on the keyboard the pin 13 responds with a brighter flicker. I have to mention there is no resistor between pin 5 and 7, there should be a 10k resistor but when i put one in flicker response stops. Is that weird, how does that affect the circuit?

Thank you very much for your guidance and patience.

[Grumpy_Mike]

I have to mention there is no resistor between pin 5 and 7, there should be a 10k resistor but when i put one in flicker response stops. Is that weird, how does that affect the circuit?

I never put a resistor between those pins so don't worry.

Glad you got it working. 

[Chole]

I never put a resistor between those pins so don't worry.

Glad you got it working. 

Thanks again Mike. Now to dwell into coding this thing. Pressing several keys in a sequence to activate a relay.