This user joined on 10/11/2017.
Using arduino's, nRF24L01 module, dht11 temp and humidity sensor, reed switch sensor. Rasberry pie as a receiver. Building front-end and back-end using PHP, MYSQL on Linux. Keeping things simple and easy to use is my mojo.
Made a phone of old tin cans, laptop fan, and a Peltier plate, converting heat into electricity to charge a 18650 Lithium Ion battery, using USB outputs to charge any compatible devices.
BlueTooth control door opener with a keypad for outside using an Arduino (of course).
Using a simple audio capable Bluetooth chip with an earphone jack to convert old devices to Bluetooth, using a 5v micro USB charge with 18650 Lithium Ion battery for long play time.
Automatic toilet flusher with a ping sensor, Arduino, some logic code, prevents a fake flush from walking by the sensor or not being in front long enough it also, doesn't flush while you still sitting.