The entry level power supply in the Unilab Retro range. The Lockable Power Unit provides a.c. or d.c. at 2 4 6 9 or 12 volts at up to 4 amps. This unit is well suited to everyday power requirements such as basic electricity ray optics boxes and immersion heaters. The voltage is selected using a five-position switch and can be locked either at a particular voltage or within a range of voltages by way of hex socket screws surrounding the selector switch. An Allen key is provided for the teacher or technician to set the desired locks.The form of the output is set by a separate switch either a.c. or unsmoothed unregulated d.c. Two shrouded 4mm sockets provide the output and the shroud can be partially unscrewed for other types of connection such as bare wires. a.c. and d.c. are output from the same sockets and never simultaneously preventing students from connecting the a.c. and d.c. outputs together.The unit has two in-built layers of protection. The first is a thermal trip on the secondary circuit with a reset button for when the problem load has been disconnected. The second is a 1A mains fuse accessed from the front panel on the primary circuit.Locking mechanism to limit or pre-set the voltage available to students in specific experiments (a standard 3mm Allen/Hex Key is appropriate for locking the voltage if the original is misplaced).4mm output socket/terminals.Thermal ""trip"" which can be reset shortly after removal of the excess load.Robustly made with captive mains lead and integral cable wraps on the back panel.Protected by a time delay mains fuse in the front panel.Complies to EN61010 2010 certificate available on request.Dimensions: (L)290mm x (W)165mm x (H)165mm.