STEVE
Monitoring the power on time of a heat pump hot water system. How many hors per day does the a/c unit run to keep the water hot?
Hot water is heated by a reverse cycle air conditioning unit. A mains power detector uses ACS712 current detector and Arduino Nano drives a relay when current is flowing. The on & off events are logged to a google sheets page using an ESP8266 via If This Then That. Annual hot water costs were estimated at $166 per year (4 adult household).
MARTIN
Talked about adding a safety warning light to a band saw. When the saw is turned off the saw continues to run for quite some time while the motor spins down. It is potentially dangerous since the machine is off but still able to cut things. Martin proposes a warning light on a timer that stays on until the motor and blade have stopped moving. Detecting when the saw is turned off and activating the warning light requires a mains detector circuit.
LEO
Showed us a tattooing machine controller. (ouch!). He also showed some spare controller boards (hot water systems?) with processor, psu, relays etc, going free! Also scooter controllers that are security locked.