A light-emitting element including a light-emitting thyristor and a schottky barrier diode is provided. In some implementations, a method is provided. The retention portion is reconfigurable between a first configuration of reduced lateral extent and a second configuration of increased lateral extent. The result is a buffered analog-to-digital converter with both low input noise and very good DC accuracy. Simplified approach avoids configuration of network topology and provides plug-and-play installation, without configuring network or improved multi-layer switch. The mechanism is characterised in that the angle-bars constitute a release mechanism which enables the three positions, stable respect to the divan bed base, while the quadrilater stiffly moves the angle-bars in other three positions.