The Raspberry Pi.
The Raspberry Pi is a very cheap small single board computer developed in the United Kingdom, in 2006, to promote the teaching of basic computer science in schools and developing countries. It is very simple to programme and it has a number of features like the 40 general input output pins that make it ideal for controlling devices such as lighting, drones, home automation setups and a variety of electrical monitoring equipment. Crucially for this installation, the Raspberry Pi has an audio outlet, which allows it to be connected to external speakers.
Simple on off switches have been connected to eight of the general input output pins of the Raspberry Pi. Four of the switches monitor the electrical activity of the circuits and four are ground pins to complete each electrical circuit. The switches are mounted on brackets below the doorhandles. Each switch is activated by the door handle being operated.
Stereo audio speakers are attached to the Raspberry Pi.
Python is the language that has been used to programme the Raspberry Pi for this installation.
The switches are activated when one or more of the doorhandles are depressed. The switch completes the electrical circuit which is being monitored by the Raspberry Pi. When the tiny electrical current is detected the programme chooses a random file from the directory of created sounds and voice recordings. This sound is then played through the attached speakers. The software allows multiple sounds to be played simultaneously. The programme is set in an endless loop, so that the sounds will be played each time a door handle is operated, until the installation is turned off.
A diagram of the general input output pins is included below.