The original relay in the Stanley unit was equipped with a 250VAC/10A relay that required a 12V coil voltage to switch. Difficult to actuate from a 5V circuit so it was replaced with a dual relay module.



Please make sure the Stanley unit is not plugged in before you start work on it.



The relay board I used has two 10A relays that will switch with a 5V coil voltage. In order to ensure a 15A rating of the hacked unit, I used the relays in parallel to provide a load rating of 20A. This provides a decent safety factor for a power adapter connected to a standard 15A breaker protected home wiring circuit. If you use a higher current relay, you could switch the power outlets individually. If the power strip is rated at 15A, then any of the outlets must be safe to operate to 15A. By wiring the relays specified for this instructable in parallel, you can ensure that any single outlet or all 3 outlets together can draw 15A safely. More load than this and the circuit breaker in your home wiring panel will trip to protect the circuit.



The power for the electronics is supplied by a iPhone USB charger. I had a spare that I could use. They are inexpensive and available on Amazon and ebay. It is cheaper to buy the charger which comes with a USB cable than to buy the components to build your own power supply. The iPhone form factor works well in the limited interior space of the Stanley unit. Use spade terminals to connect directly to the AC terminals of the charger. Use heatshrink to cover the exposed parts of the AC terminals to prevent accidental contact. The USB cable I found in my project box had a bulky molded connector. Using a sharp knife, the plastic moldings were removed. The red and black wires of the USB cable where replaced with 26 gauge wire to provide more mechanical robustness and then the connector was further protected using heatshrink as seen in the pictures.



Originally, I had intended to switch the relays independently so that I could control at least 2 outlets independently. That is how the circuit was originally wired up. After investigating the current carrying capacity of the relays, I chose to parallel the relay outputs. The connection between the Imp and the Relay board has two Imp pins controlling each relay. In reality, you can just connect one Imp pin to both relay inputs. The firmware switches both pins together so either way is fine.



The AC Neutral and the AC Ground is already connected to the electrical outlet sockets. Leave everything connected the way it comes from the factory. The only wire that needs to be modified is the AC Live wire (Black Wire). This wire needs to be t'd or branched so that you have a live wire entry to each relay as shown on the schematic. Protect the join with heatshrink. I used a small piece of 16AWG wire for this branching. 16AWG multistrand wire can typically carry 22Amps when used for short haul chassis wiring.



The relay outputs are soldered to the underside of the AC PCB as shown in the picture. When all the connections are made, squeeze everything into the housing as shown and hot-glue the relay and imp boards to the housing base.















