Sentinel GPS


Master Digital Timer

Comes with:

  • Heavy gauge #14 AWG cables and wire.
  • Super-duty 30-amp relays for long life.
  • Power switch and re-settable 15-amp circuit breaker provides over-current protection.
  • Remote temperature probe, that measures temperature inside the growing area.
  • Digital timeclock is highly accurate and backed up with a long-life lithium battery
  • Recycling timer set in hours, minutes and seconds. No fumbling with knobs or guesswork. You can even select Day, Night or 24-Hour operation.
  • Hi-temp feature prevents overheating due to fan or ventilation problems.
  • Hot-start feature protects HID lamps by ensuring proper cooling time before attempting to re-fire.


  • Controls HID lights using a battery backed up 24-hour digital timeclock.
  • Coordinates a digital Recycling timer for Day / Night or 24-hour operation.

How to use:

    • The unit comes with a metal bracket that is first attached to a wall. Secure the bracket to the wall with 2 screws. Then use the 2 thumb screws to secure the enclosure to the bracket.
    • The device(s) that will be controlled by the MDT-4 must be 15-amp or less COMBINED load. There are THREE outlets (receptacles) on the MDT-4 ONE of them is used to control the Recycling devices like pumps or fans. The other two receptacles allow both Day and Night devices to be connected so they are activated during the Daytime or Nighttime. Connect HID lights to the Light On (Day) outlet so they run during the Day. Other devices like dehumidifiers, exhaust fans etc. can be connected to the Light Off (Night) outlet to be activated only during the Night (when the lights are turned off).
    • The unit requires a 15-amp power supply. The built-in circuit breaker will protect the unit from overloads.

  • in the event of a power failure, "Hot-start" feature disables HIDs until they are properly cooled protecting expensive HID lamps.
  • Connect multiple hydroponic pumps to Digital Recycling timer. Watering times are precisely controlled day, night or 24-hours
  • Connect up to 1200 watts of HID lighting directly to the MDT-4 OR use 1 or more HPH-4 to connect as many lights as you need control.
  • Night devices such as heaters or exhaust fans are connected to the "Light Off" receptacle. When Lights are Off, the device is enabled.

Power Supply Volts 110 - 120V~ 60hz
Circuit breaker rating 15A/240V~
Timer Setting Hours, minutes and seconds
Recycling mode Day / Night / 24-hour
Min / Max operating temperature 32' to 120'F
Min / Max operating humidity 0-99% RH
Max Temperature setting Adjustable
Hot-start delay Adjustable
Dimensions 8" x 6.5" x 3.1"
Battery type Lithium CR2032


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Hydro Depot