Triggering a 5v/125VAC10A relay with a button ?

Projects Discussion and Showcase Home Automation and Networked Objects
#1

[NOTE TO MODS: This post may be in the wrong place. Please move it if necessary.]

Hello,

Just yesterday I put together a WiFi plug socket with the esp8622 based LinkNode R4. I managed to fit two 125VAC US wall sockets into a gangbox(4 separate outlets) along with a fairly hefty 5V/4A psu, terminal block, switch for the mains(only kills the 125VAC, Not the R4's PSU) and a standard 3 prong recepticle for a standard PC power cord to power everything.

Everything is working as expected so far. The LinkNode app is great, albeit slow because of the latency between my phone - the cloud - the R4. I eventually intend to reflash the R4 with new firmware that will allow it to spoof a WeMo device and therefore allow me to control it with my echo dot.

I'd also like to have the option of controling each outlet manually and believe I can do so simply soldering on to the relay's "on" pin. What I'd like to do is use those small little buttons that we all did our first led project with. Had the R4 board actually broken out more of the pins this wouldn't be an issue. I'm fairly certain I can accomplish this with a nano. What I'd rather do however, is not even waste a MCU for such a simple task.

With all of that now out of the way my question is: Is there a way to control the relays needed 5V with just one of those little buttons and some basic circuitry? IE - Can this be accomplished with discreet logic?

TIA as always

#2

After a bit more reading it seems that an eBay pro mini clone or even one of my nanos would be the best choice considering the limited amount of realestate that I'm working with. I did at one point consider PNP/NPN transistors but I am still unsure as to how a single button press would allow for this to work as I understand that to be made functional constant current must be applied. Perhaps I'm incorrect. I have very little experience with transistors.

Regardless it appears that a ProMini will easily do the trick at a very low cost and in a very small space.

If anyone else has any other ideas I would love to hear them as I haven't yet worked out all of the potential issues. If I have my Arduino send 5V to the relay as an on signal after a button press how do I turn it off from the LinkNode R4/ESP8266? It seems that I cannot actually just hijack the 5V "ON" pins from the relay. Rather, it seems that the signals from the ESP8266 need to be somehow rerouted through the Arduino. It's been a long day so I may not be thinking entirely clearly.

Again, ANY advice would be very much appreciated!

TIA,
NoCl

#3