The most sophisticated of the Unilab Retro range the Regulated Lockable Power Unit offers smooth regulated d.c. at 2 4 6 9 or 12 volts at up to 4 amps. This unit is for quantitative circuit work e.g. Ohm's law or where a constant voltage is required under variable load. 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 power is output from shrouded 4mm sockets and the shroud can be partially unscrewed for other types of connection such as bare wires. 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/terminalsThermal ""trip"" which can be reset shortly after removal of the excess loadRobustly made with captive mains lead and integral cable wraps on the back panelProtected 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.