The Wake-a-tron 3000
The Wake-a-tron 3000 is here to change waking up forever. It is designed to both make you wake up comfortably, but also guarantee that you do not snooze and oversleep. But how can we improve our waking up experience?
The most important thing is to use the elements which naturally wakes us up, light and sound. Sunlight is especially effective, and is a big part of why this system works. To make a smooth transition from deep sleep, we gradually increase the amount of light and sound over a period of 15 minutes. To prevent snoozing and oversleeping, the system has a sensor in the bed, which can tell if you are actually up or not. In addition, it heats up the room to a comfortable temperature in good time before waking you up.
Let us first take a look at the components in the system, and then we will go trough its wakeup sequence.
The bed sensor is a weight cell salvaged from a normal bath weight. It is mounted under one of the beds legs, measuring about 1/4 of the total weight of the bed. We could mount one sensor on each leg, but it proved sufficient with just one.
The weight cell is a variable resistor, which changes its resistance with a tiny amount when force is applied to it. This tiny change in resistance cannot be detected with a simple voltage divided circuit, so we must use a Wheatstone bridge and an instrumentation amplifier. The output from the amplifier is a voltage which can be read by analog input on a microcontroller.
The lights and heat oven are controlled by wireless power switches from Nexa. These operate on 433 Mhz, and can easily be used with a simple 433 Mhz transmitter from ebay or similar sources. The Nexa protocol is described here, and several libraries exist that allows easy implementation of the protocol. I will get back to this further down. The lights are normal lamps connected to the Nexa switch. The heater oven is a wall mounted electric oven, also connected to a Nexa switch.
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