Description
The MR-42/UNI is a memory (impulse) relay designed to control lighting or other loads from an unlimited number of push-button locations, wired in parallel with just 2 wires. It’s a practical, wiring-efficient replacement for traditional 3-way (staircase) and cross-bar (4-way) switch circuits, making installations simpler and faster to mount — particularly useful for retrofits or multi-point switching without running dedicated switch cabling to each point.
A key feature of the MR-42/UNI is that it memorizes its last switching state even after a supply failure: if power is lost, the relay turns off, and once re-energized it automatically returns to the state it was in before the failure. The MR-42 offers two selectable operating modes via a potentiometer on the front panel — either 2 independent parallel contacts, or the second relay set to latching operation — giving flexibility for different multi-circuit switching needs. It runs on a universal AC/DC 12–240 V supply and provides two 16 A DPDT (changeover) output contacts, with a red LED for output status indication.