# Dippy Bird binary clock

This Dippy Bird clock display is simple to build and it’s just waiting to be scaled up for use as a full clock. As shown there are only enough birds in this rendition to read out the hours. More tiers can be added for minutes and you could even add your own temperature readout function using a separate bird as the thermometer.

Other than the fact that there are only four bits of resolution, the first thing you should notice is that these birds have nothing to drink. They’re intended to dip their beaks into a glass of water, leading to evaporation that changes the temperature of the dichloromethane inside to start their teeter-tottering. Water isn’t used because the birds would be in constant motion. Instead a resistor has been placed in the base of each, which heats up when current is passed through it. A bird in motion is a digital 1, and bird at rest is a digital 0. A set of transistors protects the microcontroller from sourcing too much current. In this case an mbed is keeping time but any microcontroller will do. We’ve embedded a quick clip of the dippy bird clock after the break.

# Can a Dippy Bird be used as a temperature sensor?

Dippy birds are the toys that teeter-totter back and forth as the beak of  bird-shaped body dips into a container of water. The felt covering the beak and head picks up water and, through evaporation, cools that end of the glass tubing. The temperature changes cause the dichloromethane to either boil off, or condense, shifting the weight of the liquid thereby pivoting the glass body.

The real question is, does the temperature of the water cause the toy to move differently, and can that be measured to calculate the temperature of the water? [Craig] put that query to the test, by designing an apparatus to measure the motion of a Dippy Bird. A photointerruptor was used to measure the motion of the body, causing an interrupt each time the tail of the bird passes in between the sensor and the emitter. For control data a DS1820 temperature sensor was positioned near the felt on the head of the bird, and a relative humidity sensor captured readings at the same time. Data from the three inputs was collected over a two-day period. Although not a precise measurement, the motion of the bird did trend in the same ways that were recorded by the temperature and relative humidity sensors.