Triggering a relay input from two outputs

I have here a USB powered Nano and a radio receiver both connected to the signal input of a relay module.
The idea is that the relay activates when the nano or the radio tells it to.

However I've been having problems wiring that up. The power portion of the circuit SEEMS fine, both the relay and the radio receiver receive power from the 5V pin on the Nano.

However, in order for the signal portion of the circuit to work, I had to put diodes on the Nano output and the Radio output.
While writing this post, I realized that what I did looks a bit like a transistor or something.

Without the diodes, the relay simply won't switch state as expected when the Nano or Radio tells it to.

The circuit works ok without diodes if I disconnect either the Nano output or the radio output and use only one output.
I infer that this means the problem might lie in the radio output feeding a signal to the nano output and visa versa.

So my question is, what's going on here? And how can I simplify this signal circuit?

I've also just realized that with some extra coding, I could simply connect the radio output to a Nano input, and code the nano to pass an appropriate output to the relay. But I'd like to understand what's going on.

Many thanks in advance.

Post a schematic.

Most likely the diodes are steering diodes and help to resolve a conflict of when one output is high and the other output is low and the two outputs are connected together makes a short.

Yup, steering diodes.

Consider what would happen if the diodes are not there. The radio outputs a 0 and the nano outputs a 1, creates a short.

So is the only way to eliminate them by connecting the radio to the Nano instead, and doing some more coding? :smiley:

You could do that or just leave em be.

Alright, thank you for the explanation! :slight_smile:

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