I’m building a circuit where a Photon controls a relay which powers a Siren.
The siren consumes about 500mA and uses a 12V input voltage.
I have a transformer which outputs 12V, which I hook up to the relay as well as to a LM7805. The output of the LM7805 goes to power the Photon.
My question: Is this a reasonable setup? Also, I often see people using a few coupling capacitors with an LM7805. But I don’t have any capacitors at the moment. Do people find that they are absolutely necessary for this kind of application?