Q-RLY – Four-Way Relay Controller

CAD $54.00


Q-RLY, a member of London Power’s Q-system of switching kits, provides interfacing for four relay groups. Q-RLY is the equivalent of four Q-SR single relay controllers plus Q-LDV LED driver.

  • four independent control blocks
  • multi-way control per block
  • use with RLY subminiature relays
  • function LED driver (4 LEDs)
  • voice LED driver (4 LEDs)
  • accommodates easy DIP-switch programming (order one Q-DIP per block used)
  • requires just 12Vdc, positive or negative depending on overall system

Each of the four control blocks within Q-RLY can drive up to three RLYs. Relays provide complete isolation between the control circuit and the switched circuit, so high-voltage features such as rectifier type, triode-pentode switching, etc. can be safely controlled. In a given system, the functions of the control blocks may not necessarily correspond to voice selections, or to channels, and may be controlled from any of a number of input control lines. Each block is considered to be a “function” or “feature” controller and has its own LED to show that it has activated its output. The function LEDs use current steering, so that even if all four LEDs are lit, they only draw the current of a single LED.

The incoming control lines typically correspond to “voices” of a guitar system, and there is an onboard voice LED drive circuit. This is useful when the Q-LATCH voice selector is wired in a remote location: the Q-RLY provides local annunciation of the voice selected while Q-LATCH provides the same for the remote position.

Any number of relays may be tied to any control line and the numbers per line do not have to be the same. For more than three relays per output, change the driver transistors to MPSA42 or similar.

When combining Q-RLY with Q-FET and Q-LATCH, Q-RLY is powered from the negative supply. Assure that this supply has sufficient current available to support the relay coil load plus the LEDs. Relays used in RLY are 12mA per coil. Each LED that is lit draws about 10mA. Voice LEDs are only lit one at a time but function LEDs might all be lit, depending on whether they are used or not.

If Q-RLY is used with Q-LATCH and there are no jfets to control, the switching system can be powered from +12V or -12V depending on what supply is available.

Q-RLY can be used independently from other Q-system boards in creative custom circuits. Just assure that the supply is 12Vdc and has sufficient current for the relay load.

Assembly of Q-RLY is quick and easy with the high-quality PCB and kit notes. The mounting holes are designed to line up with those in Q-LATCH, Q-FET and Q-VX so that the boards can be stacked if required.

Q-RLY accommodates mounting of DIP switches for easy programming capability. Add one Q-DIP for each block that you want this capability on. Otherwise, jumpers are soldered where the DIPs would be to program the voice interface.

Kit requires assembly.

PCB size: 3 x 2″, 76 x 51mm

See also:

Q-DIP – Four-Way DIP Switch

For more information:
– see our page, About Our Switching Kits
– download our informative PDF: London Power Switching Kits Selection & Application (135 kB, 22 pages)